令和元年 6 月 26 日
蘭国「RWS INFORMATIE –Werkwijzer Ontwerpen Waterkerende Kunstwerken –Ontwerpverificaties voor de hoogwatersituatie Groene versie 2018」(RWS INFORMATION –Werkwijzer (Work pointer) Design Waterkerende (water turning) Artworks - Design
verifications for the high water situation Green version 2018)仮英訳
https://www.helpdeskwater.nl/publish/pages/158168/werkwijzer_ontwerpen_waterkerend
e_kunstwerken_-_groene_versie_november_2018.pdf (参照：2019/04/12)

国土技術政策総合研究所 河川研究部 水害研究室
板垣 修
生江 恵美子＊この資料は Google 翻訳によって、蘭語から英語に機械英訳がなされています。一部の単語については辞書で調べて補足をいたしました。
表紙
RWS INFORMATION –Werkwijzer (Work pointer) Design Waterkerende (water turning) Artworks Design verifications for the high water situation
Green version 2018

Date

November 1, 2018

StatusDefinitive - green version

3頁

ColophonIssued by

RWS-WVL Water barriers
1

Information

Water Help Desk

Telephone088-7977102

Performed by

Bob van Bree, Rob Delhez, Ruben Jongejan and Arnaud Casteleijn

FormatDate

November 1, 2018

StatusFinal, green version

Version number D2
５頁

Content
1

Introduction 11

1.1

General 11

1.2

Goal and target group of the work pointer 11

1.3

Scope 12

1.4

Relationship with the Guidelines for Art Works 2003 13

1.5

Status of this work pointer: green version 13

1.6

Reading guide 13

1.7

References and background documents 14

2

Design verifications on the basis of flood probability standards 15

2.1

Water Act and Building Decree 15

2.2

Flooding: exceeding the storage capacity 15

2.3

Failure mechanisms and resulting flood situations 16

2.3.1

Flooding at the site of works of art 16

2.3.2

Flooding in dike bodies 17

2.4

Practical choices with regard to cup storage in designing artworks 17

2.4.1

Bowl storage; not closing, transfer and / or overflow 18

2.4.2

Bowl storage; piping and constructive collapse 18

2.5

The probability of flooding in the Water Act 18

2.6

From flood probability standards per route to reliability requirements per failure
mechanism for individual artworks 19

2.6.1

A route as series system 19

2.6.2

Step 1: Determine failure probabilities per failure mechanism at route level 20

2.6.3

Step 2: Determine failure rate requirements per failure mechanism for an2

individual artwork or construction part 21
2.6.4

Alternative verification methods 24

2.7

Development of strength and load over time 25

2.8

Verification methods 26

2.9

References and background documents 26

3

Hydraulic loads 29

3.1

Introduction 29

3.2

Explanation of available instruments 29

3.2.1

Introduction Hydra-NL 29

3.2.2

Introduction Water level course 30

3.2.3

Introduction Risk 31

3.2.4

Introduction Water data and Ten-year overviews 31

3.3

Overview of hydraulic loads 32

3.3.1

Overview of hydraulic loads per failure mechanism 32

3.3.2

Further explanation of failure mechanism Height 32

3.3.3

Further explanation failure mechanisms do not close and structural failure 33

3.4

Applying climate scenarios 33

3.4.1

The basis: hydraulic preconditions for the Legal assessment 34

3.4.2

Translation to hydraulic framework conditions for designs 34

3.5

Other surcharges on the water level 35

3.5.1

Bui-oscillations and tubes 35

3.5.2

Seiches 35

3.5.3

Local alarm 36

6頁
3.6

Wave growth during the flood wave 36

3.6.1

Coast 36

3.6.2

Lakes 38

3.6.3

Fighting and ice delta 39

3.6.4

Lower rivers 41

3.6.5

Upper rivers Meuse and Rhine 43

3.7

Works of art behind harbor dams 43

3.8

References and background documents 44

4

Do not close 45
3

4.1

Introduction 45

4.1.1

Failure mechanism introduction 45

4.1.2

Phenomenological description 45

4.1.3

Step-by-step plan and design strategy 46

4.1.4

Safety format 49

4.2

Loads and incoming flow rate 53

4.2.1

Water levels and waves 53

4.2.2

Water level trend outside water 54

4.2.3

Emerging inflowing flow when his artwork is not closed 54

4.3

Strength 55

4.3.1

Simple design rules reliability closure 56

4.3.2

The failure probability of closure 57

4.3.3

The probability that a work of art is open 60

4.3.4

Geometry of the closed artwork, which is not high water 61

4.3.5

Bowl storage 61

4.3.6

Soil protection 62

4.4

Concrete draft opinions 63

4.4.1

Simple design rules 63

4.4.2

Detailed design 63

4.5

References and background documents 64

5

Height 65

5.1

Introduction 65

5.1.1

Introduction to failure mechanism 65

5.1.2

Phenomenological description 65

5.1.3

Step-by-step plan and design strategy 66

5.1.4

Safety format 68

5.2

Loads and occurring transfer and / or overflow flow rate 71

5.2.1

Combination of water level and waves 71

5.2.2

Water level course outside water 71

5.2.3

Occurring transfer and / or overflow flow rate 71

5.2.4

Wave overtopping as a non-stationary phenomenon 74

5.3

Strength 75

5.3.1

Turning height and width of the artwork 75

5.3.2

Bowl storage 75

5.3.3

Soil protection 76
4

5.3.4

Maximum transfer rate from a structural point of view 77

5.4

Determine the required deflection height 77

5.4.1

Determine the required height with the help of Hydra-NL 77

5.4.2

Determine the required height with the help of Riskeer 77

5.4.3

Sharper determination of throughput flow 78

5.4.4

Calculation of the mooring height 78

5.5

Relationship with the EurOtop manual 78

5.5.1

When to use EurOtop? 78

7頁
5.5.2

Dealing with different construction forms in EurOtop 2016 79

5.5.3

Tax statistics when using EurOtop-manual 80

5.6

Concrete design recommendations height artwork 80

5.7

References and background documents 81

6

Piping 83

6.1

Introduction 83

6.1.1

Introduction failure mechanism 83

6.1.2

Phenomenological description 83

6.1.3

Safety format and concise model descriptions 85

6.1.4

Step-by-step plan for design 90

6.2

Taxes 92

6.2.1

Decline on the artwork 92

6.2.2

Hanging over downstream seepage screen 92

6.2.3

Time dependence of the load 93

6.3

Strength 93

6.3.1

Retaining path length 94

6.3.2

Basis 95

6.3.3

Soil protection and filter constructions 95

6.3.4

Degradation 96

6.4

Schematization 96

6.4.1

Geometry artwork 96

6.4.2

Bottom construction under and next to the work of art 97

6.5

Measures to prevent piping 98

6.5.1

Installing filter structures 98

6.5.2

Application of seepage barriers 98
5

6.6

Tightening necessary provisions against piping 99

6.7

Other draft opinions 99

6.8

Example 100

6.9

References and background documents 100

7Structural failure 103

7.1

Introduction 103

7.2

Scope and reading guide 103

7.3

Phenomenological description of structural failure 103

7.3.1

Failure as a result of failure of water-retaining structural components 104

7.3.2

Failure due to instability of construction and ground body 105

7.4

Failure and failure 105

7.5

Limit position function structural failure 106

7.6

Reliability of a structure 108

7.7

Reliability requirements for the construction 110

7.7.1

Reliability requirement Water Act 111

7.7.2

Reliability requirement Building Decree 112

7.8

Design verifications constructive failure 113

7.8.1

When a Building Decree and Water Act Verification? 113

7.8.2

Design verification according to the Buildings Decree 115

7.8.3

Design verification according to the Water Act 115

7.8.4

Types of verification procedure 117

7.9

Step-by-step plan design verification 118

7.9.1

Design verification procedure for the high water load situation (A1) 121

7.9.2

Design verification procedure for other load situations (B) 123

7.10

Taxes 1257.10.1

Calculation values for the load 125

7.10.2High water load situation 126

8頁
7.10.3

Other hydraulic loads 134

7.10.4

Permanent taxes 144

7.10.5

Variable loads 145

7.10.6

Special taxes 147

7.11

Strength 149

7.11.1

Calculation value strength construction 149

7.11.2

Background of the partial material factor 149
6

7.11.3

Degeneration 149

7.11.4

Fatigue 150

7.12

Concrete draft opinions 151

7.13

References 151

8

Connection structures 155

8.1

Introduction 155

8.1.1

Purpose and definitions 155

8.1.2

Delimitation 155

8.2

Requirements 156

8.3

Schematization 157

8.3.1

Conflict processes 158

8.3.2

Design verification 158

8.4

Principle solutions 161

8.5

References 162

9

Soil protection 165

9.1

Introduction 165

9.2

Types of soil protection 165

9.3

Taxes 166

9.3.1

Causes 166

9.3.2

Types of tax 166

9.4

Strength 168

9.4.1

Stability relationships for flow load 169

9.4.2

Stability calculation for overflow / splash load 174

9.5

Other verifications 175

9.5.1

General 175

9.5.2

Horizontal dimensions 175

9.5.3

Vertical construction 177

9.5.4

Flexibility 178

9.6

Dealing with empirical formulations and uncertainties 179

9.7

References and background documents 179

10

Cup storage 181

10.1

Introduction 181

10.2

Size of available cup storage (Vc) 181

10.2.1

Permissible water level rise in the catchment area ((∆hkom) 181
7

10.2.2

Surface area storage area (Akom) 182

10.2.3

Other influencing factors of storage capacity 183

10.2.4

Distribution of storage capacity over several works of art 184

10.3

Inflowing volume 184

10.3.1

Emerging failure mechanism 185

10.3.2Dimensions of aquifer element (s) 185

10.3.3Occurrence of breach formation185

10.3.4Development of the flood water and the inland water level 186

10.4

Practical approach to inflow volume 186

10.5

Example 188

9頁
10.5.1

Data 188

10.5.2First approach 188

10.5.3

Second approach 190

10.5.4

Final approach 191

10.5.5Conclusion 192

10.6

References and background documents 193

11

Case 195

11.1

Introduction 195

11.1.1

Purpose of this chapter 195

11.1.2Depth of this chapter 195

11.2

Description of the situation and provisional design 195

11.2.1

General 195

11.2.2

Location 195

11.2.3

Dyke section data 197

11.2.4

Intended dimensions 198

11.2.5

Contingency concept 198

11.2.6

Layout lock sluice on main lines 199

11.2.7

Construction and soil structure 199

11.2.8Other data resulting from the preliminary design of the lock sluice201

11.3

Evaluation height (HTKW) 202

11.3.1

Step 1 Determine failure probability 202

11.3.2

Step 2 Determine critical flow rate soil protection / strength reversing device 202

11.3.3

Step 3 Determine the return height 2038

11.3.4

Step 4 Cabin storage capacity verification 206

11.3.5

Step 5 Determine the height at which available storage space is not exceeded 211

11.3.6

Step 6 Determine a recurring height with Hydra-NL 211

11.3.7

Step 7 Check that cup storage is not exceeded 212

11.3.8Elaboration with smaller cup storage 212

11.3.9Tightening with the help of EurOtop2016 215

11.4

Do not close elaboration (BSKW) 216

11.4.1

Step 1 Simple design rules 217

11.4.2

Step 2 Determine Failure probability 217

11.4.3

Step 3 Determine the maximum allowable inflow volume (cup storage) 218

11.4.4

Step 4 Determine critical flow from soil protection 218

11.4.5

Step 5 Determine maximum permissible outside water level 218

11.4.6

Step 6 Determine the likelihood of a high-water closed standing of the artwork 224

11.4.7

Step 7 Determine the required chance of closing the reversing means 224

11.4.8

Step 8 Verify that the chosen locking devices meet the requirement in step 7

11.5

Elaboration of piping (PKW) 226

11.5.1

Step 1 Determine design decay about the artwork 226

11.5.2

Step 2 and 3 Determine whether the seepage length is sufficient 227

11.6

Effective design failure 229

11.6.1

Step 1: choose the construction part to be verified 230

11.6.2

Step 2: determine the relevant taxes 230

11.6.3

Choice A or B: design verification regarding high water or other loads 230

11.6.4

Step 3: determine the reliability requirement from the Buildings Decree 230

11.6.5

Step 4: determine the reliability requirement from the Water Act 230

11.6.6

Step 5: collect the data from the construction component 230

11.6.7

Step 6: choose the strength magnitude to be verified and determine the limit statefunction / unity check 231

11.6.8

Step 7 and 8: determine the representative value and calculation value of thestrength 233

10 頁
11.6.9

Step 9: generate the marginal water level, wave height and wave period statistics
with Hydra-NL and determine the degree of mutual correlation. 233

11.6.10 Step 10: Determine the calculation value of the tax effect on the Building Decree
235
11.6.11 Step 11: verification in accordance with the Buildings Decree 240911.6.12 Step 12: Determine the calculation value of the tax effect on the Water Act 241
11.6.13 Step 13: verification according to the Water Act 242
11.7

References 242

Terms and definitions 243
Establishment and quality assurance 247
Appendix A

Process of 'Designing' incl. LCC 249

A.1

Introduction 249

A.2

Structure of the design process 249

A.3

Design of flood defense structures 251

A.3.1

Operational concept and functions 251

A.3.2

Environmental analysis251

A.3.3

Aspect analysis 251

A.3.4

Requirements 251

A.3.5

Assessment criteria 252

A.3.6

Variants 253

A.4

Verification of the design 253

A.4.1

General verification 253

A.4.2

Verification of flood defense requirements 253

A.5

Special topics 254

A.5.1

Assessment 254

A.5.2

Management and maintenance 254

A.5.3

Reliability closure in the design 254

Appendix B

Standard failure probabilities 257

Appendix C

Verification of high water load situation with dominant own weight 259

Appendix D

Wave load according to the model of Goda 263

Appendix E

Step-by-step plan for probabilistic verification of high water loads 269

10

11 頁

1

Introduction

1.1

GeneralThe vulnerability of the Netherlands to flooding is generally known and one thestrong system of (primary) water defenses is therefore unanimously regarded as one
basic condition for Dutch society. The Flood of 1953 and the near-floods in 1993
and 1995 show that water safety is continuous attention.
Most water defenses are of land. Artworks deviate in this sense that they are for alarge part made up of other materials such as steel, concrete, wood, masonry andplastic. Artworks are used for other purposes water-retaining structures such as
shipping, traffic and water management, but have to naturally comply with the legal
standard for water defense.
The Guide for Art Works will be used for the design of water-retaining structures[Ref. 2.2] has been widely used to date. The Guideline Art Works dates from 2003
and is therefore designing flood defenses at the appearance of this Werkwijzer (workpointer) works of art about 15 years old. The most important reason for this work
pointer to be changed is the legislation where an exceedance probability standard
applies switched to the flood probability standard. In addition, the building
regulations (Building Decree) has been adapted and for building constructions thework is currently being done with the so-called Eurocodes. Of course also give 15
years of development flood defense technique and 15 years of experience with the
Guidelines for Art Works 2003 cause for adjustments and improvements.
The desired safety level of hydraulic engineering works with a flood defense function
is anchored in the Water Act and the Building Decree. On both must be met andtherefore the strictest is decisive. Because both laws based on different starting
points are a direct mutual comparison is not always easy. This is particularly
important constructive failure mechanisms. Chapter 7 provides practical handles
given how to deal with this.

1.2

Goal and target group of the work pointerThis work pointer has as goal: offering methods with which the current knowledge
and current tools can be verified in a practical way design of a hydraulic engineering
11

work in a primary flood defense appropriate management and maintenancethroughout the life of the law required water retaining capacity.
The work pointer is particularly focused on the designer / constructor with several
years of work experience and also on the person who draws up the design
specifications to which a work of art must comply.
Comments:(1) The work pointer provides handles for the verification of a design based of therequirements of the Water Act / Building Decree, including the necessary for thisschematics, but is not a manual for the integral design of a water-retaining artwork.
Some general indications are given in 0 the course of a design process.
12 頁(2) In the work pointer, therefore, there are no formulas that, based on therequirements, lead to the optimal dimensions or specifications of artwork parts. If to
use the work pointer in this sense, one first has to use the estimate design quantities,
calculate whether they meet and if necessary adjust estimates.
(3) The verification of a design has many similarities with the verification(assessment) of an existing construction. Yet there are important ones differences.


Designs will continue to be looked into in the future. That's why it has to bewith it design is taken into account (to a greater or lesser extent difficult
quantifiable) uncertain aspects such as climate change, degradation, aging andsettlements within the chosen design life.



In design, other functions and aspects are also the only ones water safety (which,moreover, is outside the scope of this work pointer falls).



Assessment is based on the existing characteristics of the artwork, while theartwork is designed for designs. As a result, uncertainties can be handled
differently.

1.3

Scope
The scope of this work pointer is limited to water-retaining structures (including
denominations, safety locks, drainage locks and barge locks, inlet and outlet locks,
pumping stations). The work pointer does not deal with management (intersection)
and, tunnels, longitudinal constructions or the large storm surge barriers, although12the latter can fall within the validity range of some mechanism models.
The connections of these structures to the adjacent dike sections (Connection
constructions) and Transition constructions (for example from the soil protection or
the dike coverings on the work of art) are also up to it scope.
This work pointer is about designing and looking forward to the whole design
lifespan (taking along, for example, sea level rise and soil subsidence). This means
there are common ground with the Design Instrumentarium (including theFoundations for flood protection) but also with it Statutory Assessment Instruments(WBI). The management and maintenance of works of art are only discussed ingeneral terms in this work pointer. For this, reference is made to the essays from the
Guidelines for Art Works 2003 about this subject.
Obviously, an overall design verification must be broadened looked at the waterretaining function that is central to this guideline. In many it is up to the designer tomake suitable preconditions and determine reliability requirements.
Because of the multidisciplinary character of the design of artworks too other laws,
standards, guidelines and rules are important, such as for example the Machinery
Directive for drive systems. These fall outside the scope of this Work pointer.
13 頁
1.4

Relationship with Guide to Works of Art 2003
In this work pointer the method is from appendices B1-B5 and B7-B9 of the
Guideline Artworks 2003 [Ref. 2.2] adapted and brought into line with theprobability of flooding and the current state of the art. The basic ideas underlying
chapters 2 to 5 and Appendix B6 from the Guidelines for Art Works 2003 can inprinciple still be used. However, it must be borne in mind that the texts from thesechapters are correct parts have been overtaken by time and no longer literally apply.

1.5

Status of this work pointer: green version
This document is a green version. The instruments that work with are relatively new.
The proposed methods and methods have been tested at a limited number of cases.
Therefore suggestions for improvement and / or optimization of the suggested
methods of working. These can be provided via the Helpdesk Water.
13

1.6

Reading guide
In chapter 2, starting from the Water Act and the foundations for high water
protection [Ref. 2.1], discussed the system in which the artwork functions as part ofthe primary flood defense and the potential flood situations which lead to thecrossing of the basin power. On the basis of the main error tree for a flood defense,
the probability of failure for the artworks. The assignment will be entered of thisfailure probability space to the different failure mechanisms (do not close, height,
piping and structural failure).
Chapter 3 then discusses the hydraulic loads of apply when designing flood defense
structures. Here the main instruments discussed and climate scenarios and othersurcharges on the water level.
Chapters 4 to 7 then fail the failure mechanisms closing, height, piping and structural
failure further elaborated. At the failure mechanism structural failure is also
discussed the role of the Building Decree and the Eurocodes invoked therein.
Chapter 8 provides an initial impetus for the design of Connection Structures.
Chapters 9 and 10 give further information about cup storage and erosion resistanceof soil protection as it is particularly important for the failure mechanisms do not
close and height (chapters 4 and 5).
Finally, a case is discussed in chapter 11: a design verification for a lock.
Appendix A deals with general information about the design process. Appendix B isan addition to chapter 4. Appendices C, D and E belong to chapter 7 Constructive
to fail. Appendix C deals with the verification of the construction in the few occurring
situation that the own weight is dominant in the high water load situation. Appendix
D deals with the Goda model for the determination of wave loads on constructions
and Appendix E gives a concise step-by-step plan for a fully probabilistic verification.

14 頁
All references mentioned in this work pointer and not free or against payment areavailable, together with the work pointer uploaded on the Helspdesk Water.
14

1.7

References and background documents[Ref. 2.1] Foundations for flood protection, Expertise network Water safety, Second
revised edition, November 2017
[Ref. 2.2] Guidelines for Art Works 2003, TAW, May 2003

15

15 頁

2

Design verifications based on flood probability standards

2.1

Water Act and Building Decree
A design verification involves the assessment of whether a design meets therequirements. This concerns both usage requirements, such as requirements on theclearance height, as legal safety requirements. In this chapter the latter
requirements centrally.
Works of art that are part of a primary flood defense must both meet the standards
from the Water Act as well as the requirements of the Building Decree. The
reliability requirements that become new construction under the Building Decree
stipulated in the NEN-EN1990/NB Principles of the constructive design.
In this chapter (and also chapters 3-6) only the standards are discussed from theWater Act. The requirements from NEN-EN1990/NB are only relevant forverifications of structural safety. These requirements are included in chapter 7
Constructive failure addressed.

2.2

Flooding: exceeding the storage capacity
A water-retaining work of art does not stand alone. It is part of a dyke track that canconsist of dyke bodies, quays, dunes and structures. The dike section forms theflood defenses for a high water discharge in its totality protect the underlying area.
In this underlying area there is a certain degree of concomitant ability present.

※（Rijkswaterstaat, Central government 2018）15 頁より作成。
Figure 1 Artwork as part of a system (source: Safety Netherlands in Map 2)

16

The Water Act sets a flood probability per year1 on a dyke project. The probabilityof flooding of a trajectory should be smaller than this flood probability. The conceptof storage capacity can be derived directly of the definition of the probability offlooding as it is in the Water Act (Article 1.1) defined:______________________________
1

Opportunities per year are discussed in the context of the Water Act. This isactually a chance of failure in a continuous period (reference period) of 1 year.
Where chances in this work pointer are concerned, this concerns chances of failure
in a certain period of time, the reference period. That is why no dimensions arepresented with regard to the opportunities.
______________________________
16 頁
Flood probability is the chance of loss of water retaining power of one dyke route sothat the area protected by the dyke section is so floods that fatalities or substantial
economic damage originated.
Between the loss of water retaining power and the flooding of it protected area thatare fatalities or substantial economic damage is the capacity for storage. The
definition of the coming together power is:
The capacity to store water is the loss of waterpower can still be stored in theunderlying system without this leads to fatalities or substantial economic
damage.
The water retaining capacity of the flood defense and the combining capacity of theprotected area thus together determine the probability of flooding dyke route. It
should be noted that loss of water retaining capacity must be made read as both
failure due to failure of the flood defense and failure without failure of the flood
defense (see explanation in section 2.3.1).
For substantial economic damage can be connected in the first instance with thepractical guidance given above in the Foundations for high water protection [Ref.
2.1] is done:
Substantial economic damage occurs when the average water depth at least one
area or neighborhood with the same four-digit zip code (based on the district and17neighborhood map of the CBS) is greater than 0.2 m.
If desired or required, the above criterion can be substantiated deviated.
2.3

Failure mechanisms and resulting flood situations
A flood is the result of the loss of water retaining power should be read as failure
due to collapse of the flood defense or failure without failure of the flood defense.
The events that lead to the loss of water retaining capacity are described throughfailure mechanisms. That's how it is available storage capacity is exceeded by, forexample, the collapsing of a work of art or dyke body, through transfer over a workof art or by inflowing into a closed and not collapsed work of art. In practice animportant difference between artworks and dyke bodies that the chance of one
flooding without the failure of the flood defense in dike bodies is very small is. Thismay be different for artworks.

2.3.1

Flooding on the site of works of art
Artworks always have a watercourse behind the artwork, except for denominations.
This waterway usually forms part of a trial system which has secondary barriers. A
work of art can be done in different ways failure, with a flood as a result:A) Flooding without failure: A work of art can be so robust designed to ensure thatlarge quantities of water are closed or not to be able to enter the bosom system
without the artwork succumbs. When the maximum farm level is reached and asecondary barrier collapses, the chimney breast empties in the polder in a shorttime. (17 頁）Since outside water will continue to flow in via the artwork andthe succumbed secondary capacity, the storage capacity will be exceeded. In
this case, we speak of a flood without the collapse of it artwork as a result of ashortage of combining capacity as then there is fatalities and / or substantial
economic damage in the underlying area2.
B) Flooding due to failure with the occurrence of a progressive breach: when the
artwork is unable to construct the inflowing flow constructively to resist it will
collapse, leading to a breach. When then the flow rate of the inflowing water
becomes so large that the adjacent floods also collapse is a progressive breach.
In that case the combining capacity will almost certainly be exceeded and theprecise one size no longer important. In that case, we speak of a flood due tofailure of the artwork.
18C) Flooding caused by failure with the occurrence of a limited breach: In case of
constructive collapse where a breach arises with a limited scope, the volume of
inflowing water remains limited (er). In that case the size of salvage capability
important for the chance of failure after constructive succumb. This situationis less common than the situation in which one such a large gap is created thatin any case there will be one flood. It is assumed that exceeding of the coming
power almost certainly occurs after structural failure, conform flood situation
B.
2.3.2

Flooding in dike bodies
Dike bodies generally have a toe ditch inside the dike that connects to a system ofditches lying in the ground level (so no quays around it).Depending on the qualityof the turf, dike bodies can transfer through put of order 10-100 l/m/s resist
without collapsing. Although such flows over large dike stretches result in a large
inflow volume, the consequences often limited as long as the dike does not collapse.
The same goes for the inflow due to seepage water. The system of inner-dike water
ways will gradually fill and then water will come to the ground level. Leaving
exceptions, wave overtopping and seepage water leads to flooding, but not resulting
in flooding with substantial damage or casualties. Naturally, the determination of
the storage capacity must be taken into account be kept with transshipment overdyke bodies and seepage water.
In practice one speaks of dike bodies of a flood in the case of the collapse or erodingof the defense, leading to a progressive breach. This is rarely made explicit indesign guidelines and WBI documentation. It is assumed that the probability ofexceeding the storage capacity after the occurrence of a breach is practically equal
to the probability of a breach. This seems strongly on how to deal with structural
failure in artworks.

2.4

Practical choices with regard to cup storage in designing artworks
The way in which the available storage capacity in the design process of awater-retaining artwork plays a role can vary per failure mechanism.
______________________________
2

An additional consequence is that after the drainage of the chimney breast, thedecay over the artwork in question increases sharply and the artwork can stillcollapse with the possibility of a progressive breach in the primary flood defense.
19

_____________________________（18 頁）
With some failure mechanisms, the size of the storage capacity is one direct
design parameter and with other mechanisms is not recommended. Below are somepoints of attention with regard to dealing with cup storage in the design process.
2.4.1

Bowl storage; not closing, transfer and / or overflow
Particularly in the verification of the design with respect to non-closing andtransfer and / or overflow, the combining capacity can be an important design
parameter. In these failure mechanisms, it is generally advisable to design the
artwork in such a way that flooding (transfer and / or overflow) or inflow (notclosing) without collapse of the structure (flood situation A in section 2.3.1) isdecisive for the failure probability. The consequences of unwanted inflow without
the structural failure of a work of art are more manageable than the consequencesof breaching and possibly breach growth. In addition, it is relatively easy to design awork of art so robust that overflow volumes in closed condition and through flowing
water can be structurally resisted in the non-closed state. In general, theconstruction (concrete, steel) of the artwork is itself sufficiently robust from its
primary function (s) (passing through shipping, drainage, etc.) in order towithstand the current flow load.
An exception to the above concerns the design of the soil protection. This is often
heavily loaded by larger flow and flow rates due to the flow rates then occurring.
For the vast majority of works of art, adjusting soil protection at such high flow
rates does not lead to the most efficient design. This is because it is usually (much)cheaper to increase the deflecting height or to place an additional reticle than tostrengthen the soil protection.

2.4.2

Bowl storage; piping and structural failure
In design verifications for piping and structural failure, it is less obvious to use the
combining capacity as a direct design parameter. In both cases, the flood defense isclosed at high tide and (part of) the construction will have to collapse before large
volumes of water flow in and thus claim the storage space (flood situation B in
section 2.3.1). Although the collapse of the artwork itself is not equivalent to aflood, it is in most cases not recommended in the design to look for the edges of thepermissible and as a failure criterion to choose the overtaking capacity. The
20

recommended approach is therefore to include the failure probability with respect
to piping and structural failure to the chance of the structural failure of the artwork
itself and the likelihood that the volume of inflowing water is subsequently greaterthan the existing storage space equals to 1. The failure criterion becomes identicalto a failure criterion appropriate to the NEN-EN1990 / NB Principles of thestructural design.
2.5

The probability of flooding in the Water Act
Two different standards for the primary have been included in the Water Act flood
defenses:
1. Signaling value.
2. Lower limit or maximum permissible value.

19 頁
In the statutory assessment of the existing primary flood defense systems both thesignaling values as the maximum permissible flooding probabilities of importance.
The reference period for both chances is 1 year. In the legal assessment is the
expected situation in the last year of the assessment round.
The design verification checks whether the requirement that the failure probability
must be less than the maximum in each year of the intended life permissible failure
probability. Usually this will be the last year because there is long-term effects suchas sea level rise and material degradation. On this time aspect is discussed in moredetail in section 2.6.4. The signaling values are not important for design
verifications.
For further explanation on the different types of flooding or failure probabilities
included in the Water Act reference is made to paragraph 4.4 of the Foundations
for flood protection ([Ref.1.2]). The flood probability norms themselves can befound in various places such as

https://waterveiligheidsportaal.nl/#/home orwetten.overheid.nl/BWBR0025458/2018-0701#BijlageII respectively wetten.overheid.nl/BWBR0025458/2018-0701#BijlageIII.
2.6

From flood probability standards per route to reliability requirements per failure
mechanism for individual works of art
21

2.6.1

A route as series system
The maximum permissible probabilities of flooding from the Water Act do not
relate to individual structures or dike sections, but to trajectories. A dyke project
can be regarded as a series system. A series system is as strong as the weakest link:
if one link fails, the system fails. The probability of flooding is thus equal to theprobability that at least one of the components of the route will fail. This
relationship is schematically shown in the error tree in Figure 2.
Flooding(system fails)

Or
Dyke section
1 fails

Dyke section
2 fails

Dyke section
3 fails

The hydraulicstructure 1 fails

The hydraulicstructure 2 failOr
Failure due totransfer and / oroverflow

Failure due tonon-closing

Failure due tolower or rear

Structural
failurerunning

Failure due to failureof connection
construction※（Rijkswaterstaat, Central government 2018）19 頁より作成。
Figure 2 Display of a trajectory as a series system in an error tree.
20 頁
The chance that a work of art fails will contribute to the probability of flooding of a
project. A work of art fails if more water enters the area through or over the artwork
than can be stored there without substantial damage or casualties. This can haveseveral causes. These causes are also called failure mechanisms. Important failure
mechanisms for artworks are:· Transshipment and / or overflow;· Non-closing;· Piping (also called bottom and rear running);· Structural failure;· Failure of connection construction.

22

The probability that somewhere a work of art or construction component fails is inpractice greater than the chance that one specific work of art or construction
component fails. This phenomenon is also called the length effect. In order to beable to assess the reliability of an individual artwork or construction component, arequirement at the object or component level must be derived from therequirement at the level of the trajectory.
To arrive at a requirement for a particular failure mechanism for an individual
artwork or construction component, the following steps must be taken in sequence:
1. Determine a reliability requirement for the relevant failure mechanism atroute level.
2. Translate the reliability requirement for the relevant failure mechanism attrajectory level to a reliability requirement for the considered artwork or
construction component.
2.6.2

Step 1: Determine failure probabilities per failure mechanism at route level
Failure probes at the trajectory level can be derived by dividing the floodprobability standard over the different failure mechanisms. This breakdown is also
called the failure probability budget. A default failure probability budget has beendrawn up for WBI2017 (see [Ref.2.2]) and OI2014v4 ([Ref.2.3]). This is shown in
Table 1. It is permissible to deviate from this default failure probability budget inorder to avoid unnecessarily restricting requirements for certain failure
mechanisms.
It is recommended to evaluate at an early stage of the design process if optimizationof the failure probability budget is useful. It should also be realized that the failure
probability budget applies to an entire dyke project and that only major shifts
within the failure probability budget are of practical significance.
Table 1. Default failure probability budget from WBI2017 and OI2014.

Type of barrier

Failure mechanism

Sandy coast

Other (dikes)

Dike or artwork

Overflow or wave

0%

24%

Cracking and piping

0%

24%

Macro instability

0%4%Damage to the

0%

10%

overtopping
Dyke

23

covering and erosionof the dyke body
Artwork

Not closing

0% *

4%

Piping0% *

2%Structural failure

0% *

2%

Dune exit

70%

0% (10%) **

Other

30%

30% (20%) **

Total

100%

100%

Dune

※（Rijkswaterstaat, Central government 2018）20 頁より作成。
21 頁* Many sections along the sandy coast do not contain any works of art or dikes. If
this is the case, then will have to deviate from the default failure probability
budget.
** In the case of journeys consisting of only a part of dunes, the dune catch willoften be a relatively small one contribute to failure probability. In the default
failure probability budget in such cases a part of the post 'other' assigned to dune
catch.
For more background to the failure probability budget, reference is made to Section
5.5.1 of the Accounting Policies [Ref. 2.1].
2.6.3

Step 2: Determine failure probabilities per failure mechanism for an individual
artwork or construction component
The difference between a failure probability for a trajectory and the corresponding
failure probability for an individual artwork or construction component isdetermined by the length effect. The length effect differs per failure mechanism.
The length effect is small in the case of a failure mechanism such as transfer and /or overflow. In this mechanism the uncertainty with regard to the hydraulic load isdominant and it is spatially strongly correlated. The length effect is great for a
failure mechanism such as piping. In this mechanism, the uncertainty with respect
to the substrate properties is of relatively great importance and these properties are
spatially very variable.
In principle, the failure probability per failure mechanism for a particular artworkor construction component can be determined on the basis of a probabilistic
calculation for the trajectory. However, that is relatively laborious. For this reason,
24

fixed length-effect factors have been included in the OI2014 ([Ref.2.3]) and in the
WBI2017 ([Ref.2.2]) with which a failure probability for an individual artwork or
construction component can be directly derived. In general, it can be written:

In which:
Peis, kw

Failure probability for the failure mechanism considered for anindividual artwork per year [-]Peis

Failure probability for the considered failure mechanism at route level
per year [-]Pmax

Maximum permissible probability of flooding of the dike section(defined as a lower limit by law) per year [-]ωFailure probability factor for the relevant failure mechanism [-]N

Long-term effect factor for the failure mechanism considered

Table 2 includes longitudinal effect factors from the OI2014v4 and the WBI2017 inorder to arrive at reliability requirements for individual artworks. It is emphasizedthat these are first approximations. The values from Table 2 must be viewed in thelight of the gradual transition to a probabilistic method in assessing the reliability offlood defenses. At one probabilistic method, failure probabilities per structure, dikeand dune section are calculated and combined into failure probabilities at, forexample, route level. This provides insight into which failure probability
performance is desirable, so that the necessity disappears to work with previously
estimated length-effect factors. It is important, however, that sufficient margin isretained in the design in order to be able to accommodate future changes within
the process, such as the construction of more works of art in the process.
22 頁
It is advisable to work from coarse to fine in the design and only sharpen the length
effects if that yields substantial savings. The values from the WBI2017 must be
regarded as minimum requirements. This document connects to the approachtaken in the OI2014v4.
Table 2 Length-effect factors in the OI2014v4 and WBI2017. This document can be
regarded as a further elaboration of the OI2014v4 for works of art.

25

OI2014v4(held here)

WBI2017(for information)

Overflow or wave

N = 1-3 (depending on the

N = 1-3 (depending on theovertopping

route, see Appendix A fromroute, see Scheme of Grass

OI2014v4)

Coverings ([Ref 2.4]))

N = min (nkw; 10)

N = max (1, 0.5 × nkw,2a)

With:

With:

nkw Number of artworks in

nkw,2a Number of works of art

process where non-closing iswhose probability of failure

relevant failure mechanism

is not negligibly small

and closures minus or moreaccording to the simple test

independent from each other(-). In other words: theto fail (-). Possible to refine

number of artworks thaton the basis of probabilistic

could not be easily approved

analyzeswith regard to the reliability

Do not closeof the closure, so that adetailed assessment isrequired.
Structural failure

In the OI2014v4 there is noN=3

longitudinal effect factor
recorded but is advised tostart from CC3 from the
NEN-EN1990. This Guide isrecommended to start from
N=3
Piping (under and rear

N = min (nkw; 10)

There are no regulations inrunning)With:the WBI2017 recorded for

nkw Number of artworks inunder and backwardness

process where piping iswith an explicit relationshiprelevant failure mechanism iswith a goal reliability(-).
Possible to refine on thebasis of probabilistic
analyzes.
It should be noted that this is
for the time being only
applies to the model from26

Sellmeijer. For the rest
models are not prescriptions
included an explicit
relationship with a goal
reliability (see chapter 6).
※（Rijkswaterstaat, Central government 2018）22 頁より作成。
The length-effect factors from Table 2 serve to derive failure probabilities forindividual artworks. Sometimes a further breakdown of these failure probabilities
over different physical or process components is required.（23 頁）For example, theprobability per year of the failure of the alert must be less than the maximum
probability per year of the failure of a work of art due to non-closure. After all, aclosure can also fail due to other causes, see chapter 4. Also in the assessment of thestructural safety of construction components a stricter requirement must be
adhered to than the failure probability for structural failure at art level if there are
independent construction components with more or less equal failure probabilities.
This is discussed in more detail in Chapter 7.
Figure 3 shows a numerical example of the derivation of the reliability requirementsof the standards from the Water Act for the purpose of design verifications of works
of art.

27

Flood(system fails)

Maximum permissible flooding probability according to
the Water Act e.g. 1 / 10,000 per yearor
Dyke section 1
fails

e.g. 24%
Failure due tooverflow or wave
overtopping

Dyke section 2
fails

Dyke section
3 fails

The hydraulice.g. 2%e.g. 4%or

Failure due toFailure due tolower or rear

non-closing

The hydraulicstructure 1 fails

structure 2 fails

e.g. 2%

Structural failure

running

No single
reservation
Failure due tocollapsingconnection
structure

1/42,000
per yeare.g. N = 2

Individual

hydraulic structure
fails

1/84,000
per year

1/500,000
per year

1/250,000
per yeare.g. N = 5

e.g. N = 4

Individual
hydraulicstructure fails

1/1,000,000
per year

Individual hydraulicstructure fails

1/2,500,000
per year

1/500,000
per year
N=3

N / A (nosemi-probabilistic
method available)

Individual
hydraulicstructure fails

1/1,500,000
per yearSuppose: 3 independent
construction components withequal failure probabilities
Individual

construction

component fails

1/4,500,000
per year※（Rijkswaterstaat, Central government 2018）23 頁より作成。
Figure 3 Numerical example for the derivation of reliability requirements of a maximum
28permissible flooding probability according to the Water Act for an individual artwork and /or construction component.
24 頁
2.6.4

Alternative verification methods
The failure probability budget and the length-effect factors are only tools forverifications based on the Water Act. They make it possible to carry out
verifications per failure mechanism for individual artworks. In some cases, however,it may be more accurate or convenient to perform a verification not per failure
mechanism and per artwork, but to consider different failure mechanisms and / orworks of art collectively.
If there is a strong dependency between failure mechanisms, verification per failure
mechanism can be unnecessarily conservative. The dependence between failure
mechanisms can be included in a design verification by:
1. To add the failure probability for the failure mechanisms in question
2. The chance to determine that at least one of these failure mechanisms occurs.
The failure probability budget therefore remains the same, at most the percentages
for the conscious failure mechanisms are no longer considered separately. The
dependency between the failure mechanisms is taken into account on the side of
the failure probability calculations: it ensures that the probability that at least one
failure mechanism occurs is less than the sum of the probabilities per failure
mechanism.
In addition to refinement by more accurately incorporating the dependencies
between failure mechanisms, design verifications can sometimes also be refined bytaking the interdependencies between artworks more accurately. This can be usefulif:
1. A default length-effect factor is found to be excessively conservative and / or
2. Otherwise the interactions between artworks cannot be properly modeled.
If a default length effect factor is found to be too conservative, then the failure
probabilities per artwork for the conscious failure mechanism can be combined into
a failure probability at the trajectory level. This chance of failure can then becompared directly with the failure probability at the level of the trajectory. A
29breakdown of the failure probability at the trajectory level about the individual
artworks by means of a length-effect factor is then no longer necessary. One could
also use the result of a failure probability analysis for a series of existing artworks tofurther determine the requirement for a new artwork.
It is also possible that there are interactions between the (failure) behaviors ofartworks that make it difficult to assess works of art separately. Consideration canbe given to situations in which the consequences of transhipment over one artwork
depend heavily on the quantity of transhipment that takes place over the otherworks of art. A possible solution is then to determine the inflow volume as afunction of the outside water level for all the works of art together.3 Then theprobability can then be calculated that the storage capacity is exceeded. This
opportunity must meet the requirement at the turning height at the level of theroute. Such a method can be considerably more practical and accurate than the
splitting of the storage capacity over the individual structures.
______________________________
3

If the turning height of the structures is partly determined by whether or not

closure means are used, then the chances of the various possible inflow flows can begiven as a function of the outside water level. By combining this result with theprobability distribution of the outside water level, the probability of exceeding thestorage capacity can then be obtained. This is then the probability of failure due toeither overflow or non-closure (assuming that failure due to scouring is notnormative).
_____________________________
25 頁
2.7

Development of strength and load over time
There are no specific reliability requirements for the design in the Water Act as in
the NEN-EN1990 / NB Foundations of the structural design. Well is indicatedwhich requirement a route must at least meet. Each trajectory is periodicallyassessed on the basis of this requirement. The parts of a construction are therefore
designed in such a way that they are (expected or even with a high level) degree ofcertainty) in each year during the intended design life requirements from the Water
Act.
Initially the failure probability of a new construction can be reduced by proven30

strength. Without interference, the chance of failure will always increase over timeprocesses such as aging, degradation and relative mirror rise. Often the probabilityof failure in the last year is normative (see Figure 4)※（Rijkswaterstaat, Central government 2018）25 頁より作成。
Figure 4 Illustration of a design based on the maximum permissible flooding
probability from the Water law. The chance of failure must be smaller than therequirement in each year of the design life. The shown probability of failure
corresponds to a construction that meets the failure probability for 100 years.
In practice it is uncertain how long a particular construction meets therequirements of the Water law will comply. That is because the development of thestrength and the load cannot be predicted perfectly in time. In addition knowledge
development and the introduction of new models lead to adjustment of the imageof the reliability of a flood defense. Also these changes are surrounded withuncertainty. With these uncertainties has to be with the design taken into account.
The conservatism in the starting points with regard to the decrease in strength andincreasing the load over time determine the probability that a flood defense will
sooner than intended to exceed the requirements of the Water Act. Advised to thedealing with the uncertainties regarding the time to exceed the assess the standard
on the basis of, for example, a scenario analysis in which the effects of alternative
future developments (such as different ones) sea level rises) is checked.
26 頁
31With relatively easy-to-adjust construction components, the optimal design
durability primarily determined by the technical feasibility and the life-cycle cost
(LCC). In that case, it is advisable to start from design verifications the expected
decrease in the strength and the expected increase of the load time, roughly in linewith the G or G + climate scenario. This matches an LCC analysis in which thetime to reject as expected value or deterministic variable.
With hard-to-adjust construction components such as foundations and concrete
constructions often determine the user functions the optimal design life. With such
construction components, it is advisable to reduce the chance of the interim needto replace or strengthen. This can be done by to use conservative principles withregard to the decrease of the strength and increase of the load over time. An
example is handling a W + climate scenario.
Management and maintenance affect the development of the probability of failure
over time. These activities therefore affect the margins associated with the design
must be adhered to future changes in the failure rate of the flood defense. This also
applies to conditions of use that ensure that the chances of certain taxes are small
or absent.
2.8

Authentication methods
To assess whether the reliability of a work of art is sufficient both probabilistic,
semi-probabilistic and deterministic methods available. For more backgrounds inthese methods, please refer to section 5.6 of the Principles for flood protection([Ref.2.1]).
Chapters 4 through 7 are probabilistic and / or semi-probabilistic and / ordeterministic verification methods presented for different failure mechanisms. In
doing so, we always discuss:
1. The failure definition and the failure mechanism model (or: the limit statefunction),
2. The variables in the failure mechanism model and their uncertainties,
3. The reliability requirement for the considered failure mechanism at the level ofa work of art or construction part and4. The method for answering the question or to the reliability requirement is
met:probabilistic,

semi-probabilistic
32

ordeterministic.

With

every

semi-probabilistic rule, all are always representative values and partial safety
factors specified.
2.9

References and background documents[Ref. 2.1] Foundations for flood protection, Expertise network Water safety,
Second revised edition, November 2017
[Ref. 2.2] Regulation for primary flood defenses 2017 - Appendix III Strength andsafety, Ministry of Infrastructure and the Environment[Ref. 2.3] Rijkswaterstaat WVL, Guide Designing with Flood chances - Safety
factors and taxes for new ones Flood probability standards, version
OI2014v4, February 201727 頁
[Ref. 2.4] WBI2017 - Scheduling manual for grass cover, Rijkswaterstaat WVL,
version definitive 2.0, December 1, 2016

33

29 頁

3

Hydraulic loads

3.1

Introduction
This chapter discusses the determination of hydraulic loads necessary for
performing a design verification. The method used in this chapter is usable formost objects in the Netherlands. Use is made here of the instruments as at the timeof writing this work guide by the Ministry of Infrastructure and the Environment
delivered. For situations where this 'standard set of instruments' is not suitable, as
in harbor basins, analyzes and / or customized models are required. You can do thiscontact with the Helpdesk Water.

3.2

Explanation of available instruments

3.2.1

Introduction Hydra-NL
Below is an introduction to Hydra-NL specifically for Kunstwerken (works of art).
In front of detailed information is available in the Hydra manual NL [Ref 3.6].
Hydra-NL was created by merging the previous Hydra-Sweet and Hydra Coast.
Until recently the program was only suitable for dike profiles, but since 2017 it isalso possible to schematize vertical walls4. With this Hydra-NL can be used as adesign tool for determining the required height of artworks.
Hydra-NL is called a probabilistic model, in which the parameters (seawater levels,
wind speed, lake levels, drainage, etc.) that lead to the hydraulic load on flood
defenses (water level and waves) stochastic variables. For each tax system5,
databases are physics and statistics available. The physics databases provide thelink between the local water level and the basic toasts (e.g. seawater level, drainage,
wind speed). The statistic files describe the marginal statistic 6 of the basic
randomists. Hydra-NL compiles these marginal statistics into the tax statistics
location of the export locations, or the combined statistics on water level and waves.
This takes into account the correlations between variables and the correlations overtime. For a calculation on the site of a work of art, a bank location will be chosen in
Hydra-NL, after which the model will be the combined generate tax statistics forthe artwork.

34

The current version 2.4.1 of Hydra-NL has three modes:Assessment mode, where with the databases physics (these are the hydraulicpreconditions databases) from the WBI 2017 is counted.

Design mode, where for visual years 2050 and 2100 with adapted Statistics
files and sometimes also adapted databases of physics are counted. In thestatistics files, the effect of climate change on the statistics of discharge and /or seawater level / lake level is processed.

______________________________
4

The transhipment and overflow formulas for vertical walls from the 2003 Artwork

Guidelines [Ref 3.4] are programmed in Hydra-NL. For several reasons, theformulas from the EuroTop Manual [Ref 3.5] were not chosen. The formulas fromthe Guide to Works of Art are also somewhat more conservative, which isrecommended in the case of a design. See also chapter 5 Height.
5

Coast, lake area, upper river area, etc.

6This is the statistic of the individual stochastic variables______________________________(30 頁)For the upper rivers do the databases physics for designs differ from thedatabases for assess because of a different discharge distribution over the splitting
points. In addition, it is conceivable that one wants to take account of spatialplanning measures. Reference is made to the calculation prescriptions from OI
2014 ([Ref3.12]) for the correct (combination of) databases of physics andstatistics.


Test mode, in which you can create your own climate scenarios (by the user
can be processed in custom statistics files).

The program determines the height of the failure mechanism Hydraulic Load Level(HBN), or the height of a dike body or artwork belonging to a specified
transshipment / overflow flow rate and associated exceedance. The strengthparameter - the critical transfer or overflow rate -is treated as a deterministic
variable in the model. It is for design program is therefore suitable for the requiredcrown height of the artwork determine; for a detailed explanation, see Chapter 5
Height. It can be the other way around program also calculate the failure
probability if the crest height and transshipment / overflow flow rate are specified.
This is useful for the statutory assessment.

35

In addition, for the failure mechanisms, Hydra-NL cannot close, piping andstructural failure based on the marginal statistics calculate the exceedance
frequency lines of outside water level and waves for each output location. Using
Hydra-NL 2.4.1 it is not possible to determine the combined water level and wave
statistics required for structural failure.
3.2.2

Introduction Water level course

Here is a brief introduction of the program, for detailed information see User

Manual Water level course [Ref 3.2].

The Water Level Course tool generates one for six water systems 7 per outlet
location course of the outside water level at a specified peak outside water level. In
reality, rivers depend on many possible forms of the drainage wave of influencessuch as meltwater and quantity, period and location (s) of the precipitation. The
variation of the high water level is smaller on the coast because of the astronomicaltide, but the high water level can vary between one or more tides due to variation instorm duration and wind direction. To come to one water level course is used in the
Water Level Course tool made of a combination of slow (drain) and fast (windspeed) stochastic. Because the Water Level Course tool is meant for geotechnicalfailure mechanisms focuses on the slow stochastic devices. Here is a combination ofslow and fast stochasts chosen not the most likely is, but on the extreme side
focused on the long term.
For art works, the Water Level Translation Tool is particularly useful for it
sharpening the inflow volume over a closed work of art or by an opened / collapsed
work of art for determining the chance of exceeding the maximum capacity forstorage. It will be within the WBI water level course schematized as a block patternwith a certain storm duration.
______________________________
7

Coast (including Wadden Sea and Western Scheldt, but not the Oosterschelde),

Lakes (Ijsselmeer and Markermeer (Ijssel and Marker lake), Vecht and Ijssel delta,
Benedenrivieren (Beneden River), Upper River Maas (also referred to as Upper
Meuse) and Upper River Rhine (also referred to as Upper Rhine).
______________________________(31 頁)The default value for the storm duration is 6 hours, this value is adaptable36

within the WBI. For storm-dominated load systems with a relatively short-lived
high-water wave are indeed 6 hours a conservative assumption. However, this is not
the case for discharge-dominated systems in the case and use of the Water Level
Reduction Tool inflow volume. This is discussed further in chapter 10 Cup storage.
Wind waves also play a role in determining the inflowing flow. When waves make arelatively large contribution to the inflowing flow 8, especially at transshipment
situations, these must be combined with the water level course. This is discussed in
more detail in section 3.6.
3.2.3

Introduction Risk
Risk (Ring Test) is a software application that assesses the WBI 2017 supports.
With Riskeer hydraulic loads can be determined and for the failure mechanisms

height, do not close and constructional failure can be a failure probability being
calculated. In this case the user introduces a schematization of the strength of(parts of) the artwork, after which with the failure mechanism-model an analysis of
the strength with respect to the taxes can be executed. The result is a failure

probability for the failure mechanism in question. The Failure mechanism piping
for artworks is not included in Riskeer. With the currently applicable Riskeer
version 17.2.1, it is only possible to do so a given construction to determine afailure probability. It is not possible to have one target chance and thus the required
value of one of the input parameters (e.g. the critical flow rate of the soil protectionor the required strength of a structural component) ask. In addition, it is notpossible in Risk version 17.2.1 with another year of vision than 2023 (the year ofassessment). This makes that Risk currently still offers few options for performing
one design verification. Extensive information about the operation of Riskeer canbe found in the user manual [Ref 3.7].
3.2.4

Introduction Water data and Ten-year overviews
For some design verifications it is necessary to have water level statistics the highfrequency range (probability of occurrence greater than 1/10 per year). For thisHydra-NL is only of limited use. On the Waterdata website(https://www.rijkswaterstaat.nl/water/waterdata-en-waterberichtgeving/waterdata ) to find current water data such as water levels, drains and waves, but in addition,measurement series from the past can also be retrieved for a large number
measuring stations. This allows local statistics to be generated in it high-frequency
37

range.
A document can be downloaded for the coast on the page 'Characteristic values 9' inwhich the characteristic values of the water level for all measuring stations along
the coast. For all stations, the high water levels with frequencies are included 1 timeper 10 years, 1 time per 5 years, 1 time per 2 years, 1 time per year, 2 times per year
and 5 times per year.
______________________________
8

Waves naturally play a role in the failure mechanism height, but reliability andclosing and strength and stability in the vertical wall / high threshold inflow model
also apply to the failure mechanisms
https://www.rijkswaterstaat.nl/water/waterdata-en-waterberichtgeving/metingen9/waternormalen/index.aspx______________________________(32 頁)The same document is currently being used for the rivers composed. As longas this is not yet available, use can be made of the ten-year overview 1981-1990([Ref 3.1]). Here are the high water levels with frequencies 1 time per 10 years, 1time per 2 years and 1 time per year included.
3.3

Overview of hydraulic loads

3.3.1

Overview of hydraulic loads per failure mechanism
In short, the hydraulic loads exist on a water-retaining structure for the load
situation high water from:An outdoor water level, sometimes also the course of the outside water level
important in time.

The associated waves.

An inland water level.

In the chapters per failure mechanism is explained when outside and water levels
and when water levels must be applied.
The way of determining and applying hydraulic loads can be different are for thevarious failure mechanisms of artworks. In the table below for each mechanism it isindicated which taxes are relevant and which instrument for the derivation of these38

taxes can be used. Follow up a short explanation is provided for each failure
mechanism.
Table 3 Overview of load parameters and available tools for each failure mechanism
Mechanism

Parameters to be determined

Instrument to use * /sources

HeightOutside water level

Hydra-NL

OR outside water level course

Hydra-NL + Water level expansion tool

Wave height

Hydra-NL

Inland water level

Local data

Outdoor water level

Hydra-NL / Ten-year overviews / Water data

OR Outdoor water level trend

Hydra-NL + Water level progress tool

Wave height

Hydra-NL

Inland water level

Local data

Outside water level

Hydra-NL

Inland water level

Local data

Constructively

Outside water level

Hydra-NL

collapse

Wave height

Hydra-NL

Inland water level

Local data

Don't close

Piping※（Rijkswaterstaat, Central government 2018）32 頁より作成。
* The WBI toolkit Riskeer (see section 3.2.3) is not included in the table, although there arepossibilities to use this. At the moment this is custom work, which requires a lot of extra
effort and external assistance.
3.3.2

Further explanation of failure mechanism Height
Hydra-NL is used in a different way than for the failure mechanism for the othermechanisms. Hydra-NL can directly use this for height probabilistically determine
the crest height by means of an HBN calculation at a specified critical flow rate andthe failure probability for the mechanism. This counts Hydra-NL directly with the
combined water level and wave statistics, so that none separate design water level
and wave boundary conditions have to be determined to become.

33 頁
3.3.3

Further explanation failure mechanisms do not close and structural failure
Determination of high frequency water levels
Depending on the threshold height of the structure are lower or higher water levels
39required for significant inflow due to the non-closed structure. Hydra-NL and theWater Level Gradient tool have a limited water level range and are of limited use
for water levels with exceedance frequencies higher than roughly once every 10
years. The precise range differs per water system / export location. In that case, usemust be made of other sources such as Water data or Ten-year overviews ([Ref3.1]).
When outside water levels with an exceedance probability greater than 1/10 per
year already lead to problems with an open artwork can here in one design
verification in two ways:
1. Extrapolation of the exceedance frequency line from Hydra-NL. This is mostly aconservative approach.
2. Crossing probabilities with local water level data to derive high frequency waterlevels. Applying local water level data does have a number of preconditions:

The measurement series must be representative of the situation to whichlooking at:- The water level statistics may not be significantly affected by changes in
the water system in the past or must for this changes can be corrected.
- No changes in the water system are to be expected within the planning
period that can influence the statistics or for this purpose must be
corrected. Think of the consequences of both spatial measures such as
climate change. Notice that spatial measures in the rivers for the benefit of
the flood risk management generally have a limited impact on the highfrequency water levels (effort / effectiveness is meant for extreme
conditions).



There must be enough data for a thorough statistical analysis. If this is not
the case, the desired water level should be used fully based on the Hydramodels.

For the series of measurements use can be made of the Ten-year overviews andwww.rijkswaterstaat.nl/water/waterdata-en-waterberichtgeving/waterdata.
Decrease in incoming flow due to rising inland water level
Generally speaking, art works are either a small cup of storage directly rises withthe outside water level or a large cup storage where the water level remains moreor less constant. Sometimes, however, the situation is between these two40

extremes in and must take into account the decrease of the inflowing flow
through the artwork because the inland water level increases. In that the case also
needs to be counted with an inland water level course. This situation is not very
common and is part of a customized analysis.
3.4

Applying climate scenarios
An important difference between a (legal) assessment and the design of awater-retaining work of art is the year of visibility of taxes. With designs it is visualyear equal to the required life span of the artwork and in the case of an assessment
is the visual year of the last year of the assessment round. This means that a design
verification is actually an assessment at the end of its useful life with an estimate of
the taxes and strength as assumed to be present. (34 頁)Many types of taxes haveno or negligible differences in time, but hydraulic loads usually do. This can becaused by climate change (is processed in statistics files) but for example also
through spatial measures (is processed in physics databases).

3.4.1

The basis: hydraulic preconditions for the Legal assessment
For every statutory assessment, the Ministry of Infrastructure and Water state
databases physics10 available for all load systems (coastal and coastal) lake area,rivers, etc.) that are valid for the period between two successive Legal Reviews. For
this assessment round databases made available with year of view 2023. With these
databases physics then the local hydraulic loads, with for example Hydra-NL, on
the artwork or dyke body are derived for an assessment. In the meantime thephysics databases can be used both in Risk and Hydra-NL, without that additional(uncertainty) allowances are required. However, small differences can occur due tothe different computational techniques used in both programs, but they areirrelevant to this manual.

3.4.2

Translation to hydraulic boundary conditions for designs
For designs, an extrapolation must be made according to the year of vision thatbelongs to it at the end of the chosen design life. As a result of climate change(leading to modified statistics files compared of the assessment) and planned
spatial measures (leading to adapted databases physics for the upper rivers area)
are there for hydraulic taxes (large) differences to be expected between the present
and the distant future. Reference is made to the calculation prescriptions from OI
2014 ([Ref. 3.12]) the right (combination of) databases of physics and statistics.
41

The IPCC (Intergovernmental Panel on Climate Change) proposes global climate
scenarios, after which the KNMI translates these into national scenarios for the
Netherlands. The climate scenarios currently used are in accordance with the
KNMI'06 climate scenarios and the DGWB policy choices. For the determinationof the hydraulic boundary conditions for a visual year in the future with the help of
Hydra-NL a climate scenario should be chosen.
From January 2018 the KNMI-2006 climate scenarios (2 units: G and W +, forfurther explanation see www.klimaatscenarios.nl/knmi06),which are based on
IPCC-2005/2006. These scenarios may become available Hydra-NL eventuallyreplaced by the KNMI-2014 scenarios (at least 2 units),

which are based on

IPCC-2014. For the choice of the climate scenario affiliated with the OI 2014 v4
which states that for each design lifetime the W + climate scenario is assumed. It isalso stated that a design on "end-of-life" should indeed meet the W + requirement,
but adaptive can be applied to a middle scenario (G or G +) provided it design is
expandable. The latter will especially for the foundation and hard construction
parts for artworks do not apply as quickly.
______________________________
10

These can be found on the WBI2017 ftp server. Access to this can be requested

via the Water Help Desk.
______________________________(35 頁)In the design mode of Hydra-NL three vision years can be chosen: 2023,
2050 and

2100. Although the climate effects are exponential, it is a first

conservative approach to interpolate linearly when the required visual year between
these three view years. No policy has yet been developed for view years after 2100.
Although climate effects may be underestimated, is currently being advised tolinearly extrapolate for visual years after 2100. In the event that one more accurate
distraction is desired can be assistance through Helpdesk Water asked. Incidentally,
it is always possible to own Hydra-NL test mode climate scenarios and other visual
years. You can make your own estimates for sea level rise, lake level rise and drain
statistics. It is recommended to use specialist help in this.
3.5

Other surcharges on the water level
When determining the hydraulic loads in the year of visibility, take into account be
kept with the following surcharges on the water level:42• A surcharge for outdoor oscillations and gusts .
• A surcharge for seiches.
• A surcharge for (local) noise if not already in the water level statistics has beenprocessed.
In the Guidelines for Art Works 2003 ([Ref.5.5]), account was also taken of an
extra safety in the form of a minimum guard height (during wave overtopping) thanhowever, safety surcharge (at overflow) of 0.30 m in connection with possible
uncertainties in the water level. Since these uncertainties are currently explicit
included in the hydraulic loads comes this minimum guard height / safety
surcharge.
3.5.1

Temper oscillations and pulses
Punches and blown oscillations are short-term changes in the water level due toheavy showers and major changes or fluctuations in the wind. Right now such fees
will only be charged in the databases for it Europoort area. For other tax areas
where outside oscillations and gusts possibly relevant (coast, lake area and deltas) it
is up to the designer to estimate whether and, if so, which surcharge should becharged here. Reference is made to Section B2.2.3 of the Guide for Sea and Lake
Dykes [Ref 3.3].
3.5.2

SeichesSeiches are standing waves in a (semi) closed basin, which are short-lived increase
the water level. Presumably the Europoort area and IJmuiden the mostseiche-sensitive locations. Only in the Europoort area seiches were considered
relevant enough to take them into the hydraulic tax databases of the WBI as asurcharge on the water level; a separate surcharge so not necessary here.
For other port basins where seiches may play a role is an exploratory research done([Ref 3.10] 11). The seiche effect is for these port basins usually not relevant or
unambiguous from the measurement results. If the designer considers a seichesurcharge necessary, then this can be done with specialist assistance to thehydraulic load database.
______________________________
11

The results from this report cannot simply be used; an explanation can beobtained via the Water Helpdesk
43

______________________________
36 頁
3.5.3

Local wind
Local windings are included in the hydraulic loads at the site export locations,
except in the upper river area. In the upper rivers area local noise is also not
relevant because the water level discharge-dominated and the wind does not play amajor role in situations with a high level drain. Therefore, there is no separate
surcharge for local calls to become.

3.6

Wave growth during the flood wave
Wind waves also play a role in determining the inflowing flow. In this paragraphdeals with how these wind waves interact with it water level course can be
combined. A distinction is made here made to the tax systems such as these in the
Water Level Course tool to be distinguished: Coast (including Wadden Sea andWestern Scheldt, but not the Oosterschelde (Eastern Scheldt)), Lakes (IJssel andMarkermeer), Vecht and Ijssel delta, Lower rivers, Upper rivers Meuse and Upper
rivers Rhine.
The basic idea is that the wind set-up is combined in such a way with the waterlevel course that the peak of the wind set-up (and thus wave height) coincides withthe peak of the water level. This is a conservative approach. In In the paragraphs
below, this is further explained for the different tax systems worked out.
The peak wave height is read from the illustration point of the Hydra-NLcalculation of the required crown height. In this way is as good as possibly taken
into account the correlation between water level and wave height before a specificlocation. See also chapter 11 Case.

3.6.1

Coast
The water level course at a random location along the coast consists of the timecourse of the storm set-up and the time series of the average astronomical tide. The
top of the set-up and the top of the astronomical tide do not coincide. The phaseshift depends on the location. The storm design has one trapezoidal course for all
locations along the coast. The parameters of the trapezium depend on the water
system, see also the table below from Background Report Hydraulic Loads [Ref44

3.8]:
Table 4 Parameters trapezia time course storm set-up and phase shift coastal areas (source:[Ref 3.8])
Area / location

Time course storm set-up

Phase difference
design and tide

Zeeland and Holland coast

Trapezium, base duration = 44

2.5 hours

hours and peak duration = 2 hours
Hook of Holland

Trapezium, duration = 30 hours at-4.5 hours

half meter level and flanks from 12hours to zero meter level
Wadden Sea

Trapezium, base duration = 45

5.5 hours

hours and peak duration = 2 hours※（Rijkswaterstaat, Central government 2018）36 頁より作成。
In general, the following procedure can be used:• Make an export of the water level course from the tool Water level course. Figure 5 is atypical illustration of the water level course along the coast.
37 頁

45

※（Rijkswaterstaat, Central government 2018）37 頁より作成。
Figure 5 Export tool Water level course Coast

In the Excel file obtained in this way there are two tabs included: 'Name of
sub-area' (e.g. Dutch and Zeeland) coast) and ' Tidal walk '. By finishing thetide course of the water level the design can be reconstructed. Because of thephase shift, the top of the water level set-up does not lie at T = 0 but at theDutch and Zeeland coast for example at T = -2.5 hours.



The wave growth follows the design of the water level and grows from 0 on thebasis of the trapezoid shape of the setup to the maximum value (1.50 m in thisexample) at the top of the storm (in this example at T = -2.5 hours). In Figure
6 this is visualized for one example location along the coast.

38 頁※（Rijkswaterstaat, Central government 2018）38 頁より作成。
Figure 6 Course of water level (left vertical axis) and wave growth (right vertical axis) up
example location IJmuiden
3.6.2

Lakes
46

The water levels for the IJsselmeer and the Markermeer (IJssel and Marker laker)
are described by a trapezoidal shape of the wind set superimposed on a stationary
course of the lake level at the level of the 90% percentile. The wind set has a
trapezoidal shape with a base duration of 40 hours and a peak duration of 2 hours.
Figure 11 shows a characteristic image of the water level course a random locationin the lake area.

※（Rijkswaterstaat, Central government 2018）38 頁より作成。
Figure 7 Export tool Water level course Lakes
39 頁
It can be seen that the course of the water level exactly follows the wind set up and also has a
trapezoidal shape with a base duration of 40 hours and a top duration of 2 hours. The wave
growth follows the design of the wind / water level and thus grows from 0 on the base fromthe trapezium shape (T = -20 hours) of the set-up to the maximum value on the top of thestorm at T = -1 hour. The wave height then remains at a maximum until T = + 1 hour andwalk back to 0 at T = + 20 hours. In Figure 8 this is visualized for a random location where
the wave height in the illustration point of the Hydra- NL calculation is 1.50 m.

47

※（Rijkswaterstaat, Central government 2018）39 頁より作成。
Figure 8 Course of water level (left vertical axis) and wave height (right vertical axis) on
example location Ijssel Lake
3.6.3

Fighting and ice delta
Both the Vecht delta and the Ijssel delta are divided into four sub-areas 12. For the
Ijssel delta applies that there are two principle forms for it water level course, for
the Vecht delta each sub-area has one water level gradient line with its own shape.
In Figure 9 and Figure 10 this is displayed.

※（Rijkswaterstaat, Central government 2018）39 頁より作成。
Figure 9 Water level course Ijssel delta area 1+2 (left) and area 3+4 (right)_________________________________
48

12

The boundaries can be found in paragraphs 10.3.3 and 10.3.4 of [Ref 3.8]_________________________________
40 頁©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）40 頁より作成。
Figure 10 Water level course Vecht delta area A (upper left), B (top right), C (lower left)and D (bottom right)
It can be seen that each sub-area has its own breakpoints:
Table 5 Overview of the articulation points of the water level course in the Vecht and IJssel
delta areas
IJssel Delta 1-4

Vecht delta A

Vecht delta B

Vecht delta C

Vecht delta D

T = -264 hours

T = -252 hours

T = -204 hours

T = -240 hours

T = -288 hours

T = -24 hours

T = -180 hours

T = -168 hours

T = -96 hours

T = -72 hours

T = + 24 hours

T = -96 hours

T = -84 hours

T = + 84 hours

T = + 84 hours

T = + 384 hours

T = -24 hours

T = -24 hours

T = + 312 hours

T = + 336 hours

49T = + 24 hours

T = + 24 hours

T = + 180 hours

T = + 96 hours

T = + 384 hours

T = + 264 hours※（Rijkswaterstaat, Central government 2018）40 頁より作成。
From Hydraulic Loads Vecht and IJssel Delta [Ref. 3.9] shows that it is for sub-areas Vecht
delta C and D would be too conservative the wave growth directly on the water level design
because of the long duration that this would entail bring. That is why for the Vecht and IJssel
Delta the wave growth is linked to the wind set up.
In the calculation of the hydraulic loads in the Vecht and Ijssel delta is account is taken of a

trapezoidal course of the wind set-up. In The figure below from Hydraulic Loads is Vecht-

and Ijssel delta [Ref 3.9] the course of the wind design (see the black line), which ischaracterized by a basic duration of 48 hours and a top duration of 2 hours.
41 頁※（Rijkswaterstaat, Central government 2018）41 頁より作成。
Figure 11 Schematic representation of the time course of the storm (wind speed) (source:[Ref 3.9])
50

The wave growth follows the design of the wind / water level and thus grows from 0 on thebase from the trapezium shape (T = -24 hours) of the setup to the maximum value on the
top of the storm at T = -1 hour. The wave height then remains at a maximum until T = + 1
hour and runs back to 0 at T = + 24 hours. In Figure 12 this is visualized for a random
location in sub-area C where the wave height in the illustration point of the Hydra-NL
calculation is 0.43 m.

※（Rijkswaterstaat, Central government 2018）41 頁より作成。
Figure 12 Course of the set-up of water level and wave growth at sample location Vecht deltaC
3.6.4

Lower rivers
There is a large number of sub-areas in the sub-river area (> 10). It goes too far togive an example of all of these areas water level course. Some typical examples arein shown below.

51

42 頁

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）42 頁より作成。
Figure 13 Water level course for sub-rivers sub-area 4 (upper left), 5 (top right), 7 (bottom
right) and 10 (bottom left)
In the calculation of the hydraulic loads in the sub-river area consider the same

trapezoidal course of the wind set-up as in the Lake District (Background Report

Hydraulic Loads ([Ref 3.8]) page 60). This is shown in Figure 11 from [Ref 3.9]
which is included in the previous one section. The course of the wind set-up is also
in the lower river area characterized by a basic duration of 48 hours and a top
duration of 2 hours.
The wave growth follows the design of the wind / water level and thus grows from 0
on the base from the trapezium shape (T = -24 hours) of the setup to the maximum
value on the top of the storm at T = -1 hour. The wave height then remains at a
maximum until T = + 1 hour and runs back to 0 at T = + 24 hours. In Figure 14
this is visualized for an arbitrary location in the Lower River sub-area 7 where thewave height at the illustration point of the Hydra-NL calculation is 1.50 m.

52※（Rijkswaterstaat, Central government 2018）42 頁より作成。
Figure 14 Course of the design of the water level and wave growth at the example location
Lower Rivers 7
43 頁
3.6.5

Upper rivers Maas and Rhine
There is also a large number of sub-areas in the upper rivers area (> 10). It goes
too far to give an example of all of these areas water level course. Some typicalexamples are in shown below figures. It can be seen that the drainage waves are allup main lines have the same shape.

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）43 頁より作成。
Figure 15 Water level course over rivers Rhine part area IJssel_down (left) and Lek962_up(right)53

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）43 頁より作成。
Figure 16 Water level course over rivers Meuse area Maas_5 (left) and Maas_3 (right)
In the calculation of the hydraulic loads in the upper rivers area no account is takenof the duration of the wind. For the calculation of the wave growth is therefore
assumed that the wind set-up is the same trapezoidal course as in the lower riverarea (see previous section). The course of the wave growth over time can then bedone in an analogous manner be determined.
3.7

Artworks behind harbor dams
It often happens that works of art are located behind harbor dams that the reducewaves on the outside water. The output points of the hydraulic however, tax
databases are usually outside these port dams. In first authority can be chosen to
design with the tax combinations outside the port. No physical processes are taken
into account such as wave transmission, reflection, refraction, diffraction and local
wave growth may affect wave conditions in the port. Incidentally, the wave
conditions can for a location in the port are also less favorable than the wave
conditions at the location before the port entrance (due to specific properties of aport in combination with said physical processes). As a design with wave loads
outside the port may produce an inefficient design in more detail to the Hydraulicloads are looked at in the port. Any feeling for this can are obtained by varying theorientation of the artwork. (44 頁) In that case, the hydraulic boundary condition
must be at the location of the export location can be translated to the preconditionat the location of the artwork. The Hydraulic Charges for Harbors (HB Havens)
tool is available for this. With using this tool, a simple and advanced analysis can bemade the hydraulic loads in the harbor basin. More information about this tool canbe found in [Ref 3.11]. In particular the advanced analysis requires one
54comprehensive and multidisciplinary approach. Specialist is recommended for thisturn on help.
3.8

References and background documents[Ref 3.1] Ten-year overview 1981-1990, National Institute for Coast and Sea /RIKZ, 1994 [Ref 3.2] User manual Water level course - version 3.0.1,
HKV LIJN IN WATER in the name of Rijkswaterstaat WVL, March2017[Ref 3.3] Guidelines for Sea and Lake Dikes - Basic report, Technical Advisory
Committee on Flood Defense (TAW), December 1999
[Ref 3.4] Guideline for Art Works 2003, TAW, May 2003
[Ref 3.5] EurOtop - Manual on wave overtopping or sea defenses and related
structures, Second edition, Pre-release October 2016
[Ref 3.6]

Hydra-NL User Manual version 2.4, HKV LINE IN WATER in order
Rijkswaterstaat WVL, May 2018

[Ref 3.7]

Ring Test User Manual, version 17.2.1, Deltares, November 27, 2017

[Ref 3.8] Background report Hydraulic Loads, Legal Assessment instrumentation
2017, Deltares, feature 1230087-008- HYE-0001, September 2017
[Ref 3.9] Hydraulic

Loads

Vecht-

en

IJsseldelta,

Legal

Assessment

instrumentation 2017, Deltares, feature 1230087-005, April 2017
[Ref 3.10] Seiches - Analysis of water level measurements and influence generating
mechanisms, Deltares, feature 11200537-009-ZWS- 0001, final,
October 2017
[Ref 3.11] Hydraulic Loads Ports - User manual and method, Aktis Hydraulics andHKV LIJN IN WATER by Rijkswaterstaat WVL, December 2017
[Ref.3.12] Operating instructions for the hydraulic design prerequisites Supplement

OI2014,version5(Hydra-NL

2.4.1),

characteristic 11202226-009-GEO-0002, final, May 201855

Deltares,

45 頁

4

Do not close

4.1

preface

4.1.1

Introduction failure mechanism
The presence of a water-retaining artwork in a flood defense is first authority for afunction other than water retaining. The primary function relates to the desire togoods, people, vehicles or liquids or gases pass through the flood defense. Without
this primary after all, the artwork was not needed. As a result of this primary function
should offer an artwork an opening in the flood defense. This in particular, makes awater-resistant work of art stand out from a flood defense consisting of dikes / quays
and / or dunes. The failure mechanism is not closing is therefore a unique failure
mechanism that only plays with artworks. To be able to turn a high water will be theopening and thus the artwork (must be closed at high tide).
The choice of reversing means and thus also the reliability of closing is strongly
dependent on the primary function. Of course, the water defense function also serves
to be covered, but both functions can lead to contradictory requirements direction.
As an example, an inlet lock, where the primary function requires water to flow fromoutside to inside (matching reticle: slider) but the function watering is mostefficiently filled in if one reversing device that closes (flow) on its own when influx
a check valve or waking door.

4.1.2

Phenomenological description
A detailed description of the failure mechanism not close can be recovered in thetest report of the WBI [Ref. 4.1]. The failure tree is shown in Figure 17 below.

56

And

Or

And

And

And

※（Rijkswaterstaat, Central government 2018）45 頁より作成。
Figure 17 Do not close failure tree failure mechanism
46 頁
Failure to close failure due to the failure mechanism occurs when it inflowing volume
of water through an opened work of art is so large this leads to substantial damage and/ or casualties (flood consequences). To fail of the flood defense does not occur if not
closed:(1) Showing a high water,AND (2) The artwork prior to this high water is open,
AND (3) The closure of the artwork fails, through which unwanted
outside water can flow in,AND (4a) The artwork itself succumbs as a result of failure of soil protection
with substantial damage and / or victims (flooding) as a result
13.To do this, the soil protection must first be left behind collapse

the artwork. Then arise pitfalls in the (no longer protected)
substrate, after which the stability of the artwork is lost with aresult (advancing) breach in the flood defense. It is assumed that
this situation always leads to the exceeding of the storage capacity.
OR (4b) The artwork itself remains standing but it flows in volume is notpossible due to the closed artwork are stored in the underlying
57

(water) system without causing substantial damage and / or
victims (flooding).
The final phase (phase 4) concerns the actual failure of the flood defense.
4.1.3

Step-by-step plan and design strategy
The starting point for the step-by-step plan for the design verification for nonclosing is that in addition to the dimensions and the strength of the soil protection,
the number and type reversing means required from the primary function (s) is
known. In the following the step-by-step plan (see Figure 18) is then considered thesituation where the artwork is not closed high water and a high water applies. Thisimplies that the requirements with respect to the functioning of the reversals fromthe primary process have a direct impact on this failure mechanism. Below is a stepby-step plan that is a possible one method to come to the design with respect to not
closing. Every step is briefly explained below the figure. The order given in the figureof steps is not required, because the present design assignment may not fit exactly
on the basis of the step-by-step plan. In that case, all steps are needed to go through,but perhaps a different order than optimal.
______________________________
13

In a practical sense it is possible that a work of art collapses as a result of the

inflowing water, without this leading to major consequences (damage and / orcasualties). This is because the storage facility is very large and the growth in thebreach remains limited. From the primary function of the work of art, however, suchan approach will not be desirable in the design. In the case of an assessment basedon water safety, it can be used to demonstrate that the requirements are met.
______________________________

58

47 頁
Step 1
Determine whether it is possible, based on simple

Welldesign rules, to provide the hydrauric structure witha negligible failure probability contribution for nonclosure without additional analyzes.

Not

Step 2

Determine failure probability Peis,KW,NS

for not closing from the function water
defense.

Step 3

Step 4

Determine the maximum

Determine critical flow throughno flood effects occur.

protection.

admissible inflow volume where

open artwork from soil

Step 5Determine the maximum permissible outside waterlevel (hbui, toel.) with the hydrauric structure not closed

and the probability of this water level P (hbui ≥hbui, toel.).
Step 6
Determine the chance of not high water being
closed from the hydrauric structure at
approaching high water (Popen)
Step 7
Determine the derived failure probability perclosing question for the reversing means (Pns, eis)on the basis of the failure probability and theresults from steps 5 and 6.
Step 8Check whether failure probability per closing

question of the chosen set of retractors (Pns) is
less than or equal to the derived failure
probability per closing request (Pns, eis)

Well

Ready
59

Not

※（Rijkswaterstaat, Central government 2018）47 頁より作成。
Figure 18 Do not close step-by-step plan for design failure mechanism
48 頁
Below is a brief explanation of the steps:
Step 1. In this step it is checked whether it is from the primary function, but also
costs and other preconditions are possible for the artwork and designing hisheadlights in such a way that the artwork is evidently safe with respect to not
closing. The basis for this is simple design rules (see section 4.3.1). When
this is possible, there is no need further analysis before not closing.
Step 2. The failure probability for failure to close (probability of failure per year) canbe determined on the basis of the (standard) failure probability budget andthe failure probability contributions of the other objects in the dike section
concerned (see paragraph4.1.4.1).
Step 3. As explained in section 2.2, a flood occurs at the exceeding the coming
capacity due to the inflow of outside water. In this step, the maximum
admissible inflow volume of water (that is, the storage capacity). The
maximum permissible inland water level with no flooding effects yet
occurrence (OKH) is of importance here, together with the surface and thecharacteristics of the cup storage. This becomes chapter 10 further elaborated.
Step 4. If the artwork is not closed in a high-water way, water flows through theobject. The soil protection is then taxed by this flow. The strength of this soil
protection can be expressed in one maximum allowable flow rate and then on
the basis of the Inland water level is calculated back to a maximum permissible
inflowing flow (see also chapter 9 Soil protection). The decay and the outdoor
water level also determines the occurring flow velocities.
Step 5. With the help of the results from step 3 and 4 the maximum outside waterlevels are determined when the water is not high water closed artwork is notjust a too large inflowing volume water (step 3, cup storage) or a too large
inflowing flow (step 4, soil protection). The inland water level and the
inflowing volume cannot be seen separately, because the Inland water level
during a flood water is influenced by the inflowing volume. When the bowl isrelatively large, the decay will be over increase the artwork during a high water
wave because the Inland water level does not rise or only partially rises withthe outside water level. This higher decay then leads to higher flow velocities.
The previous means that when determining the maximum permissible
60

outside water level the basis of the analysis is formed by a consideration of thecup storage. The course of the outside water level (high water wave) and thus
the course of the inflowing flow, the total inflow volume and ultimately thecourse of the Inland water level in time are the components of the requiredconsideration.
The frequency of exceedance determined in the above manner maximum
permissible outside water level actually indicates how often per year or withwhat chance there is such a high water that there is one flooding would occur
if the object never turned upside down would be closed. This exceedance
frequency is equal to the number closing questions per year from the highwater function. In this step you can the Hydra-NL and Water level course.
49 頁
Step 6. The use of the artwork from its primary function determines how often andhow long a work of art is not closed high water. This can be determined withthe use of the artwork how great is the likelihood that the artwork will still bepresent at an approaching high tide must be closed. This opportunity is
indicated with Popen14.
Step 7. With the help of the data from step 5 and 6, starting from the failure
probability for not closing (step 2), determine the maximum failure
probability per closing question of the reversing means.
Step 8. In this last step, it is checked whether the chosen reversing means (from theprimary function and perhaps also from the water retaining function) a failure
probability of closure per question (possibly including a recovery option) thatis less than or equal to the derived failure probability for the closure perquestion (step 7). If this is not the case, the various steps are again followedby tightening or other choices are made. One can even go back to step 1 anda whole consider new barrier concept. In step 2 you can look again whether
the derived failure probability for non-closing can be tightened by reduce thenumber of artworks that are of interest. This is possible for example by afurther analysis of the probabilities of failure to close to perform the rest of
the works of art or perhaps even to adjust it of other works of art by applying
other inversions or optimizing the closing protocol.
4.1.4

Safety format

61

The starting point of the safety format is the requirement that the failure probability
for non-closure of Pf, KW, NS is less than or equal to the failure probability for not
closing Peis, KW, NS, or:This forms the basis for the verification of the design with respect to non-closure.
Below is a detailed discussion of the determination of the failure probability (section
4.1.4.1) and the calculated failure probability (section 4.1.4.2).
4.1.4.1. Determination of failure probability is not closed
This requirement is derived from the legal requirement for the standard route andcan be determined using the following formula:

In which:
Peis, KW, NS

Failure Chance for not closing an individual artwork for areference period of 1 year [-]Pmax

Failure Chance for the entire dike section (standard route) basedon the maximum permissible probability of flooding from theWater Act15 [-]ωNSFailure probability factor for not closing [-]NNS

Length effect factor for non-closing [-]______________________________
14

There are situations where Popen does not concern a chance but a frequency. Thiscan be the case in particular with frequently deployed structures (for example
drainage locks).
15

In the Water Act this is referred to as the lower limit______________________________
50 頁
In the WBI2017 [Ref. 4.3] and OI2014v4 [Ref. 4.2] is a standard failure probability
budget for a standard route. In this standard failure probability budget for the

failure probability space factor for non-closing (ωNS ) a value of 0.04 arrested.
62

Deviating from this is possible, see chapter 2 for this design verifications.
The length-effect factor NNS is not equal to the number of works of art for not

closing the dike section considered, where the failure mechanism does not close anon- negligible contribution to the probability of flooding and whose closures moreor less independent of each other. That means that at it design of a work of art the
number of existing works of art in it dyke track must be known as well as theircontribution to the failure probability of it dyke section for not closing . If thecontribution of the other works of art does not known, it can be assumed that theseother works of art all contribute. In addition, sufficient margin must be establishedwhen determining the N value are held to record future changes within the process
able to capture, such as the construction of more works of art in the process.
Thereby being a maximum of 10 independent, equivalent failure probability
contributions are advised to prevent too much conservatism.
4.1.4.2. Determination of failure probability not close
The failure probability for failure to close Pf, KW, ns follows from the failure tree in
Figure 17. The following events can be distinguished:
1. The artwork is open at an approaching high water, or there is a need for
closure (Popen).
2.

Failure of the high-water closure of the work of art (Pns) and failure of repair of
the failed regular closure (Pf,herstel).

3. 3. Failure of the soil protection behind the structure (limit state function ZNS1).
4.

Failure of the artwork as a whole after failure of the soil protection has takenplace (limit state function ZNS2).

5.

Exceeding the storage capacity (limit state function ZNS3).
It can be seen from the failure tree in Figure 17 that:

Here is:Pf, KW, NS

Risk of flooding after non-closure [per year]

Popen

Opportunity on open flood barrier with a closing question [-]PNS

Probability of failure closure with a closing question [-]Pf;herstel

Probability of failure to recover from failed closure [-]63

P (ZNS1 <0)

Risk of failure of soil protection [-]P (ZNS2 <0)

Chance of collapsing artwork in the event of a collapsed soil
protection, also called Pf, KW |erosie bodem

P (ZNS3 <0)called [-]Probability of exceeding the storage capacity [-]The first term in formula 4.3 concerns the probability that the artwork is open
when a high water is present. The second and third term indicate what the chances
are that the artwork is not closed at the moment the outside water level it becomesso high that there are flood effects on the inside occur. This concerns a failure
probability per closing question from the function high water times.
51 頁
The last term indicates how many closing questions per year arise from thefunction of high water times. If it is assumed that the chance of failure of a work ofart after erosion of the soil protection is equal to 1, then this last term reduces to:

Then the following applies:

Either:

The limit state functions for failure of the soil protection ZNS1 (formula 4.6) andfor exceeding the composting power ZNS3 (formula 4.7) are shown below:

Here is:
Qc

Critical flow rate at which soil protection collapses [m³ / s]

Qin|open

Acting inflowing flow through the artwork at a certain water level giventhat the artwork is not closed high water [m³ / s]qc

Critical inflowing flow with respect to the soil protection [m³ / s / m]

Bsv

Power-carrying width soil protection [m]64uc

Critical flow speed soil protection [m / s]hbi

Inland water level in relation to NAP [m]hbb

Height top soil protection [m + NAP]

Vc

Maximum available volume of storage capacity in the hinterland, where
no significant consequences (flooding effects) occur [m³]Vin|open

Inflowing volume due to the closed artwork for a high water flow a highwater

period [m³]Akom

Coming away surface [m²]Dhkom

Maximum permitted level increase in the hinterland [m]ts

Duration of the high tide wave [s]Under the simplifying assumption that all strength terms in formulas 4.6 and 4.7
are (almost) deterministic, the last term in formula 4.5 can finally be rewritten to:
52 頁

An important load variable in both comparisons is the total inflowing flow Qin|open
by the non-flooded closed artwork. Depending on the geometry of the artwork
when it is not high-water-tight, different models are applicable to determine thisinflowing flow. Roughly, the following models exist to determine the inflow rate:Vertical wall / high threshold. There is no direct contact between inside andoutside water. This situation occurs, for example, in the case of a lock in which
the flood-tight closing means are not closed and water flows over the lockdoors.



Low threshold (spillway). There is direct contact between inside and outside
water and the inflow surface is not limited at the top. This situation occurs, forexample, in the case of a flood barrier, when the flood defense is not closed.



Drowned tube. There is direct contact between inside and outside water andthe inflow surface is limited on the upstream side. The waterway in the
artwork through which water flows in is completely under water. This situation
occurs, for example, in the event that a discharge channel consisting of a tube
is not closed by the flood defense.

65

Vertical wall / high threshold

Low threshold

Drowned tube※（Rijkswaterstaat, Central government 2018）52 頁より作成。
Figure 19 Do not close diagrammatic representation of impulse models
53 頁
The strength variables Vc and qc/uc (depending on the soil protection, see chapter
9 Soil protection) are the available storage and the critical inflow flow/the criticalflow rate for soil protection. These are further elaborated in section 4.2.3.
For the strength variables are also calculation values. For the collapse of a work ofart given the collapse of the soil protection is initially maintained that this always
happens as soon as the soil protection has collapsed. Tightening of this is possible
requires a specialist consideration outside the scope of this work guide falls. The
use of this additional strength, if any, fits incidentally better when assessing thanwith designs. Recommended for designs to be cautious about this.

66

4.2

Taxes and incoming flow
The hydraulic loads determine in combination with the inland water level and thegeometry of the non-high-watered closed artwork the inflowing flow Qin|open. For
the hydraulic loads, this depends on the geometry and the associated in-flow model
for a combination of water levels and waves (for model vertical wall / highthreshold) or sec water levels (for models low threshold and drowned tube).
Besides the absolute values of water levels and waves also play a role in the waterlevel. This allows the outdoor water level to be determined with the available
storage room (Vc) is still sufficient to reduce the inflow volume during one highwater (V in|open ).

4.2.1

Water levels and waves
The different in-flow models as included in this manual will be fed with data on
water levels (all models) and waves (only model vertical wall / high threshold, seetable 6)

Table 6 Need for input of various influx models
Inset model

Outside water level

Waves

Vertical wall / high threshold

Yes

Yes

Low threshold

Yes

No

Drowned tube

Yes

No

※（Rijkswaterstaat, Central government 2018）53 頁より作成。
This applies to the 'vertical wall / high threshold' inflow model should be made of
combined statistics of water levels and waves. This combined statistic can bederived from Hydra-NL (see method at height in chapter 5). This allows the
chance of occurrence of a combination of outside water level and waves are
determined in the case of a known defensive height in a closed state that is not highwater leads to exceeding the critical flow or critical inflow volume.
This applies to both the 'low threshold' inflow model and 'drowned tube' No role
16 games with the incoming flow. Here you can use Hydra-NL exceedance
frequency / probability of that outside water level shall be determined at these inflow models lead to the critical flow or the critical inflow volume.
______________________________
16

With the low threshold model in particular, situations are conceivable in which67waves do indeed contribute to the inflow flow. Consider a situation with a relatively
small water depth above the threshold in combination with large waves. In that case,better use can be made of the vertical wall / high threshold model.
_____________________________(54 頁)To this end, an exceedance frequency line should be used with Hydra-NL

made. If the failure mechanism does not close, the inflow can occur at the notbeing closed is already leading to a relatively high frequency at outside water levels
to flooding consequences. In Hydra-NL frequencies are higher than once in the 10
year (exceedance probability is 1/10 per year) not included in the databases. Whenoutside water levels with an exceedance probability greater than 1/10 per year
already lead to problems with an open work of art then there are two methods
possible. These are included in section 3.3.3.
4.2.2

Water level course outside water
The course of the flood wave in time determines how much water there is during ahigh tide wave due to the artwork not closed to high water can flow in. This volume
of incoming water is important to be able to assess whether the combating capacity
is exceeded. In the chapter cup storage (chapter 10) will be discussed further here.

4.2.3

Emerging incoming flow when his work is not closed
This section deals with the formulas with which the inflowing flow can be
determined at the time the artwork is not high-watering is closed. This inflowing
flow depends on the situation (geometry) of the artwork at the moment that it is
not closed (see section 4.1.4.2).
In the literature (including Applied fluid mechanics, hydraulics for hydraulicengineers ([Ref.4.4])) can provide more information about the models and thecoefficients are found. Especially the drain coefficients can be subject are ofextensive studies. For the usual works of art it is recommended to these coefficientsin the first instance with simple approximations to determine then to accept. It
should be noted that when designing the primary function the drainage coefficients
can already be looked at. There can be when designing the water-retaining
function may already be used.
4.2.3.1. Inlet vertical wall / high threshold
68For the 'vertical wall / high threshold' inflow model, please refer to section 5.2.3 ofthe Height section. This model has been extended described.
4.2.3.2. Inflow model low threshold.
For this situation, there are two models that both have their own formula know for
the inflowing flow: the complete and the imperfect spillway. The formulas for the
spillway are presented in the literature in various ways displayed. Here is chosen
for a way in which work is done with levels compared to NAP. It is also assumed
that the outside water is so large that the water flow speed towards the artwork isvery small, causing the energy level outside the dike is equal to the outside waterlevel.
For the imperfect spillway, the inland water level has an influence on the size of the
inflowing flow. The model has the following formula and the associatedprecondition with regard to the outside water level in relation to the inland waterlevel and the threshold height.
55 頁

For the complete spillway, the inland water level no longer has any influence on the
inflowing flow:

Here is:Qin,onvolk.

Emerging incoming flow through the artwork involving one imperfectflow [m³ / s]

Qin,volk.

Emerging incoming flow through the artwork involving one complete flow
[m³ / s]B Width of the flow opening [m]monvDrainage coefficient for the imperfect spillway [-]mvol

Discharge coefficient for the complete spillway [-]hbi

Inland water level compared to NAP [m]hdr

Top threshold compared to NAP, which in practice is the top of thebottom of the artwork is [m]hbu

Outside water level compared to NAP [m]694.2.3.3. Immersion immersed tube
In this situation the water-carrying element is completely under water. In front of adrowned tube the following intake formula applies:

Here is:Qin,koker

Acting incoming flow through the artwork involving one drowned tube
[m³ / s]A

Minimum area of the through-flow openings [m²]μDischarge coefficient for drowned tube [-]hbi

Inland water level in relation to NAP [m]hbu

Outdoor water level compared to NAP [m]The formula for the drowned tube (formula 4.11) has many similarities with theformula for the imperfect spillway (formula 4.9). The drain coefficients are
explicitly different.
4.3

Strength
The strength of a work of art with regard to non-closing consists of a number ofparts (see also formula 4.3c):
1. The reliability of the closure (Pns), which also includes the failure probability of
the recovery (Pf,herstel).
2. The likelihood that a work of art will not be closed at a high water level whensuch a high water occurs that in the event of a non-closed work of art this leads
to flooding consequences in the hinterland (Popen).

56 頁
3. The geometry of the work of art in a non-high water closed condition, consistingof the then present retaining height and the dimensions of the through-flow
opening (s). The geometry, in combination with the inland water level,
determines the load on the soil protection (the inflowing flow Qin|open) and thecup storage (the inflowing volume Vin|open).
4. The characteristics and scope of the available storage capacity of the underlying
water system (Vc). (See chapter 10 Bowl storage)
5. The structure and dimensions of the soil protection behind the artwork.
70

The first two parts determine the chance of the artwork not standing high-waterclosed at the moment that this is required. Parts 3 to 5 relate to the result when
they are not closed in a high-water condition.
4.3.1

Simple design rules reliability closure
A work of art can be designed in such a way (design, functioning and number andtype of reversing means) that an analysis with respect to non-closing can beomitted immediately, because it is clear in advance that the probability of flooding
is negligible. To this end, a number of simple design rules have been drawn up that
apply to specific types of works of art. A few simple test rules are also included inAppendix III Strength and safety of the WBI2017 ([Ref 4.3]). The design rules are
partly derived from this. The design rules are more specific and stricter. The latterin particular leads to fewer simple design rules than simple test rules.
The simple design rules mentioned in the following subsections do not cover allconceivable situations. This means that in practice works of art can occur of which
it can already be indicated in advance that the contribution to the flood risk isnegligible, but that do not fall under the simple design rules. If a detailed analysis is
not carried out in that case, it must be demonstrated by means of a qualitative
analysis, supported by global quantitative considerations, that the contribution to
the flood risk is negligible. Arguments for this can be found in the (limited)dimensions of the water-carrying elements, the threshold height in the non-closed
state, the use of the artwork or the (very) limited consequences when the artwork
remains open.
Regardless of how it is designed, it is desirable to include at least one reversal
element in the current-carrying elements of a work of art at all times17.

4.3.1.1. Locks
If a lock is provided with at least two high-watering heads and also the lockchamber is capable of turning the same high water, a further analysis of nonclosing is not necessary as long as the following condition is met: the lock doors arenever all open at the same time (for example, to grant a free passage to the ship inthe event of no decay, or to allow water to be discharged via an opened lock).
______________________________
17

The simple testing rules of the WBI2017 or further analyzes may show that no71

turning device is required to meet the reliability requirement under the Water Act.
For a design, however, it is not considered desirable to include any turning agent
with a work of art in the primary flood defense. In the event of a disaster or
maintenance, it is important that a work of art can still be closed off, even if it is only
to prevent damage.
_____________________________
57 頁
If the above simple design rule is met, this means that the lock is always closed highwater. Only in case of a calamity (collision) it can occur that this is not the case.
Acceptance is considered under strength and stability and therefore does not affectthe failure mechanism to close.
4.3.1.2. Grinded
When a pumping station is provided with two independent high-level reversing
devices which are connected to the pumping operation, no further analysis of nonclosing is required. 'Switching the pump operation' means in this case that they
open when the pumping station starts to rotate and that they automatically close
when the pumps are stopped. The independence implies that one of the reversing
means consists of a non-return valve (or possibly a guard door) and that the otherreversing device is, for example, an automatically closing butterfly valve. These
reversing devices are independent because they do not have the same drive andenergy source and are far enough apart so that they cannot both be blocked
simultaneously by the same obstacle.
When a pumping station is provided with several milling passes (pressure cookers)
and all of these are provided with two reversing means which satisfy the description
above, a further analysis of the pumping station is not required.
When a pumping station is equipped with reversing means which comply with theabove, the chance of undesired opening and the inflow of such amounts of waterthat this leads to flooding consequences is negligible.
4.3.1.3. Load sluice / sewer overflow
Drainage locks can be risky objects with respect to not closing. However, there arecases where this risk is very small. In the following case, a further analysis of non72

closure is not required.
A drainage sluice with an internal diameter of less than or equal to 1 m, provided
with at least one high-water reversal that closes automatically and of which thewater-carrying element (conduit) enters the outside of the impact zone of the flood
defense in an (inspection) pit, the access of which at least at ground level.
In this case the risk is negligibly small, because the chance of a closed reversing
agent is large. In addition, the consequences of failure of the closure will be limited,
because the pipe diameter is limited and the risk of breaching is negligible.
4.3.2

The failure probability of closureThe probability that the closure of a work of art fails is one of the mostimportant parameters for the failure mechanism. The size of this opportunity
depends on a number of aspects:

The use of the artwork in relation to its primary function, being the passing of
the flood defense by water, goods, people, vehicles or vessels.

The number and type of reversals.

The number of flow openings.

The emergency organization of the manager concerned.

Possibilities for possibly closing the artwork in an alternative manner with a

58 頁

failing regular closure (Pf,herstel).
When designing a work of art, it is recommended to not initially take into accountthe positive contribution of the chance of recovery. This implies a failure
probability of recovery (Pf,herstel) of 1. This does not detract from the fact that thepractical design can take into account possible possibilities for an alternative toclosing a work of art. This could include, for example, accessibility and accessibilityof the power-carrying elements of the artwork by people and equipment.
4.3.2.1. Failure of regular high-water closure (Pns)
The probability of regular closure is indicated by the parameter Pns and knows theunit per question [1 / question]. The size of this opportunity is influenced by four
sub-processes: alarm, mobilization, operation and technical failure. The emergency
73

organization, elaborated in, among other things, the flood scenario, has a major
influence on these sub-processes.
The value of Pns can roughly be determined by three methods.
1. With the help of score tables (see Determine the probability of not closing per
closing question with score tables ([Ref 4.5] and Guide to assurance of reliabilityof closure in scenarios [Ref 4.6]) This method applies to reversing devices thatare not closed at exercise of the primary function (s) of the artwork but only
when approaching a high water.
2. Using standard failure probabilities for reversals that are closed regularly fromtheir primary function. In Appendix B, this has been done for a number of
frequent reversals.
3. Using an advanced error tree analysis. Such an analysis is particularly important
for larger, more complex works of art.
For works of art, a combination of methods 1 and 2 can also be useful if both
specific high-water retainers are present and reversals that are also used in the
primary process.
Depending on the chosen method, the operation of the artwork and theinterdependence regarding the failure of the closure, the number of flow openings
in the analyzes can be included. In the first method, a failure probability of theclosing of the specific high-water defenses is determined per flow opening. If
several flow openings are present, the use of these flow channels determines how
they can be taken into account when determining the total chance of the closure
failure.
Example: A drainage lock has two tubes that are always used simultaneously. The
reversing means consist per tube of a non-return valve and a manuallyoperated slide. It is known that the failure probability of non-closing is
dominated by technical failure. The total failure probability of nonclosing Pns is determined using method 1 (score tables) for the slide andmethod 2 (default failure probabilities) for the non-return valve. The
failure of the closure of one tube is virtually independent of the closureof the other sleeve. (59 頁) The table below shows the various eventswith their chance of occurrence. It should be noted that the probability74

of failure per box (Pns) is in any case less than 10-2 per question.
Scenario

Tube 1

Tube 2

Opportunity

Both closed

Close

Close

(1-Pns)·(1-Pns) ≈ 1

Sleeve 1 not closed

Do not close

Close

Pns·(1-Pns) ≈ Pns

Tube 2 not closed

Close

Do not close(1-Pns)·Pns ≈ Pns

Both are not closed

Do not close

Do not close

Pns·Pns = Pns²※（Rijkswaterstaat, Central government 2018）59 頁より作成。
The probability of all scenarios added together 1. When failure occurs if at least
one of the tubes remains open (the probability of this event equals Pns + Pns - Pns 2≈2Pns) serves in the further analysis (inflowing flow) to take into account a water-

carrying cross section equal to the flow area of one tube. The other event where
failure of the flood defense occurs is when both tubes do not close. The probabilityof this is equal to Pns² per closing question. In that case, the flow-through surface ofboth tubes must be applied together in the further analysis. In practice it is almost
always the case that the probability of failure per tube is small, so that theprobability that one tube is not closed (2 · Pns) is substantially greater than the
chance that both tubes are not closed (Pns²). The last chance is often negligibly
small.
4.3.2.2. Failure of recovery from a regular closure
In determining the probability of failure of a closure, the chance of recovery from afailed regular closure (Pf,herstel) can also be included. This means the possibility thata failure in closing can possibly be closed in an alternative manner.
Example: An inlet lock consists of a pipe through the barrier with a pipe diameterof 1.0 m and a sliding shaft in the crown. Such an inlet lock can possibly
still be closed if the retention means are not closed by pouring clay orsand bags into the pipe via the slide shaft.
In the score tables (see method 1 in section 4.3.2.1) recovery of the regular closing
process is already included, as well as the influence of a possible second turningmeans. An additional (alternative) closing method can, however, still be charged
separately.
For the second method to determine Pns (standard failure probabilities), the75

probability of recovery can be explicitly included. This is not yet processed in thestandard failure probabilities.
In an advanced error tree analysis, recovery possibilities in case of a failed closure
are included as standard.
The probability that the recovery of a failed regular closure will depend to a large
extent on the available time between the moment of the regular closure and themoment the water is so high that inflow can no longer be stopped. (60 頁) In
addition, issues such as the accessibility and dimensions of the artwork play animportant role.
4.3.3

The chance that a work of art is open
When a high water approaches and the artwork is already closed, the failure
mechanism does not necessarily close. It is therefore important to consider how
often and / or during which part of the time an artwork is open. This obviously has
a direct relationship with the primary function (s) of the artwork and more
specifically with that of the high-water retainers. When designing a work of art, it istherefore important to make an estimate of the required input from this function(s).
The probability that a work of art is not closed (Popen) consists of two components(see also WBI2017 [Ref. 4.1]).
1. The first component concerns the period over which the artwork actually
exercises its primary function (s) and the high-water retarding means are
therefore not closed. In case of an approaching high water, a closure is thenrequired to make the barrier high-water-bearing.
2. The second component concerns the conditional probability of the artwork
standing open after a closure of high-water retaliators has failed due to theirprimary function. This component therefore represents the period over which
the flood defense is not closed in a high-water way because the reversing means
are under repair and a closure is therefore also not possible.
The above components must be viewed separately in an analysis of a work of art
and be included in the considerations. Because every situation and every work of
art is unique again, it is not possible to give a generally applicable wording for Popen,76

which means that you can always work.
Formula 4.12 gives a global general formulation for Popen. This is also included in
WBI2017 ([Ref 4.1]). This formula is based on a number of assumptions. The
most important are:

Closures occur throughout the year, regardless of the chance of high water;

The probability of non-closure (Pns) in a regular closure is the same as theprobability of non-closure if this occurs from the point of view of high water;Repairs that prevent the barrier from closing can only be caused by the failureof the closure. Other causes such as maintenance are not considered. The
implicit assumption is therefore that maintenance will be carried out in aperiod in which a high water level cannot be expected (monitoring waterlevels) or where measures have been taken to guarantee the high-level
function during maintenance (alternative flood defense).

In the case of repairs as a result of a failed closure, the barrier remains in the
open state during the entire repair period.

In which:
Popen

Total chance that a work of art is open at the moment of an approachinghigh water for a period of one year [-].

61 頁
Nopen

The number of closing questions from the primary function (s) of a workof art [1/year].

Topen

The average duration per cycle of opening and closing in which theartwork comes from his primary function (s) is open [year].

Trep

The average amount of time needed to make a failed closure of the highwater mark reversing / repairing means from the primary function (s)[year].

The repair duration can be estimated with a design based on possible failure causes
and the expected speed with which these failure causes can be remedied. It should
be borne in mind that this is the time required to restore the high-water function,
possibly with temporary facilities.
77Formula 4.12 is somewhat special because it does not result in a pure chance. This
becomes clear when the product of the number of closing questions (Nopen) and therepair time of a failed closure (Trep) is large. As a result, it is possible that in theabove formulation Popen gets a value that is greater than 1. This thus indicates that
there is a somewhat forced formulation and that for each situation a separate
consideration of the possibility of the artwork standing open in the event of an
approaching high water to be made. In a number of cases the given formula will bedirectly applicable.
ExampleA lock with lock doors and a separate high-water door that is closed as standard at
the end of each day (after 12 hours). If the recovery time of a failed closure of thehigh-water door is 8 hours, the following may apply:

In the above result it is visible that the formulation of Popen as given by formula 4.12
initially allows the repair time to participate directly in the probability of being
open. Under the condition that the probability of non-closing at a regular closure(at the end of the service) is equal to the probability of non-closing in the situationthat the lock is in operation and high water is present, this will eventually lead tointerpretation of the basic formula 4.3 to the correct approach to the failure
probability for non-closure
4.3.4

Geometry of the closed artwork that is not high water
The geometry of the artwork determines how much water flows in and how thishappens, given that the artwork is not closed high water. This geometry is includedin the various intake models (see section 4.2.3).

4.3.5

Bowl storage
For the purpose of determining the reliability of the closure, the storage capacity
must be converted into a flow per running meter by the non-high-water-tightclosed artwork. From recasting of formula 4.7 it follows that there is / is noquestion of exceeding the capacity of the storage as follows:

78

62 頁

Here is:Qin|open

Average inflow through the artwork [m3 / s]Akom

Compressing surface [m²]Δhkom

Permitted level increase for storage [m]tsDuration of high-water wave [s]It should be noted that the above formula is based on a schematization of the highwater wave as a block with a constant time duration and a constant inland waterlevel (for example when the combing capacity is very high). For systems with a'short' load duration (coast, lakes) this is usable, for systems with a long-term load
(rivers, deltas) not. For these systems, the output of the Water Level Gradient tool
must be used to correctly determine the inflow volume. For more information, seechapter 10 Cup storage.
If inflow can be schematized with the model vertical wall / high threshold (seesection 4.2.3.1), the above formula is included in a schematic high water wave as a
block with a constant duration in formula 5.15 (see chapter 5). It should be notedthat this may be applicable in the case of a lock, in which the deflecting height of
the inner door (s) that is not flooded is to be derived or verified with therequirement for not closing.
The method of determining the parameters Akom, Δhkom and ts is discussed in thechapter on Reservoir Storage (chapter 10).
4.3.6

Soil protection
The strength of the soil protection must be converted to a flow per running meterby the closed artwork that is not turned upside down. From recasting of formula
4.6 follows that:

Here is:Qin|open

Average incoming flow through the artwork [m3 / s]uc

Critical depth average flow speed soil protection [m / s]
79

hbi

Inland water level in relation to NAP [m]hbb

Height top soil protection compared to NAP [m]Bsv

Power-carrying width soil protection [m]Because the inflowing flow rate in the in-flow models 'drowned tube' and 'lowthreshold' depends on the inland water level and can rise during undesired inflows,
this inflowing flow is not constant. However, the critical flow from soil protection is
also not constant because it also depends on the inland water level. For these inflow models it is therefore recommended to first look at storage, so that the courseof the inland water level during a high water wave is clear, and then determine thecritical flow rate over time.
63 頁
For the 'vertical wall / high threshold' model, the above formula goes over in theformula given in the chapter on height:

Here is:qos/olAverage throughput / overflow flow over the artwork per linear meter [m3/ s / m]B

Width of the crown of the artwork [m]The critical flow rate of soil protection is often known from the design of the otherfunction (s) of the artwork. If this is not the case, then this critical flow rate can be
determined on the basis of Chapter 9 Soil Protection. The parameters hbi and hbb
speak for themselves and are also discussed in chapter 9.
4.4

Concrete design recommendations
The design strategy for non-closure aims to design the artwork in such a way that itmeets the requirements for not closing from flood risk management. Because thedesign and the use of the artwork are mainly determined by the primary function of
the artwork, the design strategy for non-closure is largely based on the determinationof which direction means can meet the requirement for not closing. It is
recommended to initially strive for a robust solution. This means that when therequired safety can be achieved relatively easily by applying conventional reversing
80

means, this is preferable to the optimal use of the residual strength in the form ofcup storage and strength of the soil protection.
4.4.1

Simple design rules
A design based on simple design rules is preferred. After all, this ensures that not
closing is not a normative mechanism and can be easily tested in the statutory
assessment. However, the number of situations in which simple design rules can beused is limited.
In addition to the limits to the practical application of the simple design rules, it also
applies that from an economic point of view it must lead to a desired solution. For
example, the cost of turning a lock into a double high water can be considerably
higher than for a lock with a cavity and the inner head substantially lower than thehigh water turning outer head.

4.4.2

Detailed design
If the simple design rules cannot be met, further analysis is required. This can bedone on the basis of the step-by-step plan presented in this chapter. Depending on
the specific situation, a limited number of steps may suffice. An example of this is avery large cup storage, in which it is clear in advance that this will never be decisive.
When designing via the step-by-step plan, it is recommended to initially designrobust as well. The extra costs, for example in the form of an additional retraction,
are often relatively limited at construction, while relatively much certainty can begained. (64 頁)With large objects this is usually not the case and extensive analysis
can hardly be prevented.

4.5

References and background documents[Ref. 4.1] Delhez, R, WTI 2017 Test rules for art works - Test report Reliability
Closure, Deltares, 1220087-002 GEO-0009, Version D1, December
2015[Ref. 4.2] Rijkswaterstaat WVL, Guide Design with Flood Opportunities – Safety
Factors and Taxes for new Flood probability standards, version
OI2014v4, February 2017
[Ref. 4.3]

Ministry of Infrastructure and the Environment, Regulations for the81Safety of Primary Welds 2017 - Appendix III Strength and safety,[Ref. 4.4]

Nortier, Applied fluid mechanics, hydraulics for hydraulic engineers,
ISBN 90-401-0318-6, 1996

[Ref. 4.5]

Rijkswaterstaat WVL, Working method to determine the probability of
not closing per closing question with scoring tables, 1 November 2017,
Definitive[Ref. 4.6]

Rijkswaterstaat WVL, Guide to assurance of reliability of closure in
scenarios, Background report for the use of the score tables for the
failure mechanism not to be closed, November 2017, Definitive[Ref. 4.7] WBI2017 - Schematization manual reliability closure of the work of art,
Rijkswaterstaat WVL, final version, January 2, 2017

82

65 頁

5

Height5.1

Introduction

5.1.1

Introduction failure mechanism
The deflecting height of high-water structures must be large enough to keep theamount of wave overtopping or overflow within acceptable limits. A design
verification of the requirements of the Water Act involves a flood with significant
consequences. In this chapter, handles are given to determine the required heightof a water-retaining work of art. This is relevant for works of art that independently
take care of the vertical height, such as lock locks, flood barriers, loading andunloading locks and denominations.
For works of art in which the vertical height is provided by the dike body (such as
divers and pressure pipes), a verification of the artwork on transhipment and/or
overflow is not relevant.
By far most of the constructions where transfer and/or overflow is relevant, it
concerns a vertical rigid wall on relatively deep water. For this type of construction
the method described in this chapter is therefore arranged. Different design types
are discussed briefly in section 5.5.
The method explained in this chapter is aimed at an assessment using Hydra-NL.
This was chosen because, at the time of writing this Riskeer, Riskeer is still
structured as an assessment tool and not as a design tool. For example, Riskeer iscurrently not equipped to take climate developments into account. It is expectedthat the functionality of Riskeer will eventually be made suitable for designs.

5.1.2

Phenomenological description
A detailed description of the failure mechanism handling and/or overflow can befound in chapter 4 of the WBI test track report Height [Ref. 5.1]. The failure tree isshown in Figure 20 below.

83

Failure of hydraulic structureby transfer and/or overflow

Or
Exceeding storage capacity(1 and 2a)

Failure due to erosion
during transhipment

and/or overflow (1 and 2b)
And

Falling soil protection

behind hydraulic structure

Collapse hydraulicstructure due to erosion
subsoil※（Rijkswaterstaat, Central government 2018）65 頁より作成。
Figure 20 Failure tree failure mechanism transfer and/or overflow
66 頁
Failure as a result of a shortage of altitude occurs when there is so much waterflowing over the high-water-tight closed artwork or connecting structure as a resultof wave overtopping and/or overflow, which leads to substantial damage and/or
casualties (flooding consequences). Failure of the flood defense occurs when:(1) presenting a high waterAND(2a) The work of art itself will remain, but the inflowing volume due
to wave overtopping and/or overflow cannot be recovered in theunderlying (water) system without this leading to substantial
damage and/or casualties (flooding).

OR(2b) The artwork itself collapses as a result of failure of soil
protection with substantial damage and/or casualties (flooding)as a result. For this, the soil protection must first collapse
behind the artwork. Subsequently, excavation pits form in the(not more protected) subsoil, after which the stability of theartwork is lost, resulting in a (progressive) breach in the flood
defense. It is assumed that this situation always leads to the84exceeding of the storage capacity.
5.1.3

Step-by-step plan and design strategy

5.1.3.1. Roadmap
For transhipment and/or overflow the situation is considered where the artwork is
closed high-water. Figure 21 shows a possible method that can be used in many
situations. It is assumed that the soil protection has already been dimensioned fromother functions of the artwork and that there is a considerable storage space behind
the artwork. Figure 21 shows the steps that are set in the design process in thismethod. Each step is briefly explained below the figure.
There are also situations conceivable in which a different method is optimal, forexample when storage is clearly decisive. In that case, an assessment can be made of
the critical flow in step 2 on the basis of storage and verification will take place instep 5 on the basis of the strength of the soil protection and the structural strength.
It is important that in the design verification all components (soil protection,
structural strength and cup storage) are discussed.

85

67 頁
Step 2

Step 1

Determine critical flow qc over closed

Determine failure probability Peis, dsn, HT

hydraulic structure from: a) soil protection,from water retaining functionb) structural strength of turning means
Step 3
Determine the required height hkh of
the hydraulic structure using HydraNL

Step 4
Verify whether critical storage capacity Vc is exceeded at
a constant height hkh and data (h, Hm0) from thecorresponding illustration point from step 3.

not

well

Step 5
Ready

Adjust height hkh and determine the criticalflow qc from storage
Step 6Use Hydra-NL to determine the required

deflecting height of the artwork on the basisof critical flow rate storage from step 5

Step 7
Verify again whether cup storage is exceeded
at a recurring height and data from an

notillustration point (h, Hm0) from step 6.

well※（Rijkswaterstaat, Central government 2018）67 頁より作成。
Figure 21 Step-by-step plan for design failure mechanism handling and/or overflow
Below is a brief explanation of the steps indicated:
Step 1.

The failure probability for height can be determined on the basis of the
failure probability space distribution and the length effect factor N forheight in the relevant standard path. This step is explained in more detail86

in section 5.1.4.
Step 2.

In this step, it is determined which flow rate due to wave overtopping
and/or overflow over the closed art work is permissible without thisleading to (a) collapse of the soil protection behind the artwork or (b)structural collapse of the windings as a result of dynamic effects due tothe overflowing beam. The smallest flow rate of both failure modes isused as input for step 3. This is further elaborated in section 5.3.3 (soilprotection) and section 5.3.4 (constructive failure of retarding
materials).

Step 3.

As soon as the failure probability and the critical transfer/overflow flowrate are known, the required turning height of the artwork can be
determined. Use can be made here of Hydra-NL. In Hydra-NL, thehydraulic load level HBN is determined with the failure probability andthe critical flow rate as input parameters. Section 5.4 discusses thedetermination of the required deflection height in more detail.

68 頁
Step 4.

It must be verified whether the combining capacity is not exceeded at thecalculated turning height from step 3. The water level course can be used
to determine the course of the water level, the water level and wave
height from the illustration point of the Hydra-NL-calculation from step
3 as input. This step is further elaborated in paragraph 5.3.2. If the
combining capacity is not exceeded, the calculated turning height iscalculated in step 3 and the calculation process is completed. If thestorage capacity is exceeded, then continue with step 5.

Step 5.

In this step the height is determined whereby the available cup storage is
not exceeded. This includes a certain value of the maximum
transfer/overflow flow rate.

Step 6.

With the maximum occurring transfer/overflow rate from step 5 and thefailure probability from step 1, a new turning height and corresponding
illustration point are found in Hydra-NL by means of an HBN
calculation.

Step 7.

On the basis of the height from step 6 and the water level and wave
height from the corresponding illustration point, it can be determinedagain with the help of the Water Level Gradient tool whether the cup
storage is exceeded. If this is not the case then the calculation is finished.
87If this is the case, then steps 4 through 7 are repeated again.
Steps 4 to 7 are further elaborated in section 5.3.2 and chapter 11 Case.
5.1.3.2. Preferred strategy
In the above-mentioned step-by-step plan, the required deflecting height for acertain failure probability is determined on the basis of the available strength fromstorage and soil protection18. In other words: the turning height is the design
variable. In principle, the strength of the soil protection or the size of the cup
storage can also be adjusted. For the vast majority of works of art, however, thisdoes not lead to the most efficient design. This is because it is usually (much)cheaper to increase the turning height than to strengthen the soil protection or toincrease the storage space. The storage capacity and the strength of the soil
protection are therefore taken as starting points in this method.
It is good to realize that the strength of the soil protection and (less obvious) thesize of the cup storage are parameters that can be influenced by the designer insituations where the further raising of the artwork is not possible or no longer
efficient.
5.1.4

Safety format
The starting point of the safety format is the requirement that the failure
probability for transshipment and/or overflows Pf, KW, HT is less than or equal to thefailure probability for transhipment and/or overflow Peis, KW, HT or:______________________________
18

The critical flow rate of soil protection is often known from the design of theother function (s) of the work of art.
______________________________
69 頁
This forms the basis for the verification of the design with regard to height. Below
is a detailed discussion of the determination of the failure probability (section
5.1.4.1) and the probability of failure present (section 5.1.4.2).

88

5.1.4.1. Determination of failure probability
The failure probability is derived from the legal requirement for the standard routeand can be determined with the aid of the following formula:

In which:
Peis, KW, HT

Failure Chance for height of an individual work of art for areference period of 1 year [-]Pmax

Failure Chance for the entire dike section (standard route) basedon the maximum permissible probability of flooding from thewater act19 [-]ωHTFailure-space factor for altitude [-]NHT

Length-effect factor for height [-]A standard failure probability distribution for a standard route is included inAppendix III Strength and safety of the WBI2017 ([Ref.5.5]) and OI2014v4 ([Ref5.2]). In this standard failure probability distribution a value of 0.24 is used for the
failure probability factor for height (ωHT). This value applies to both the heightrequirement of the dikes (failure mechanism for grass cover erosion crown andinner slope) and of the structures in a standard route. Deviating from this ispossible but rarely takes place in practice. Note: it is not possible to adjust the
failure probability room factor for height for (individual) artworks. Adjustment of
the failure probability distribution can only be carried out at standard path level.
See Chapter 2 for this.
The length-effect factor NHT is equal to 1, 2 or 3 and is independent of the numberof works of art in the standard trajectory. The value of NHT can be found for eachroute in Appendix A of OI2014v4 ([Ref 5.2]).
5.1.4.2. Determination of failure probability of transfer and/or overflow
The failure probability for transshipment and/or overflows Pf, KW, HT follows fromthe failure tree in Figure 20. The following three partial failure mechanisms can be
distinguished:
1. Failure of the soil protection behind the artwork (limit state function ZHT1).
2. Probability that the artwork as a whole will collapse after failure of soil
89

protection has taken place (limit state function ZHT2).
3. Exceeding the storage capacity (limit state function ZHT3).
It can be seen from the failure tree in figure 20 that:______________________________
19

In the Water Act this is referred to as the lower limit______________________________
70 頁
Here is:P (ZHT1 <0)

Risk of failure of soil protection [-]P (ZHT2 <0)

Chance of collapsing artwork in case of collapsed soil protection,
also called Pf,KW|erosie bodem called [-]P (ZHT3 <0)

Likelihood of exceeding the storage capacity [-]If it is assumed that the chance of failure of a work of art after erosion of soil
protection is equal to 1, then formula 5.3 reduces to:

The limit state functions (Z-functions) associated with the part-feedingmechanisms 1 (failure of soil protection) and 3 (exceed capacity of the comb) aredefined as follows:

Here is:
Qc

Critical flow rate at which soil protection collapses [m³/s]

Qos/olActing transhipment/overflow flow over the artwork for a specific one
water level [m³/s]
90

qc

Critical transfer/overflow flow with respect to soil protection [m³/s/m]

Bsv

Power-carrying width soil protection [m]B

Width of the artwork [m]qos/olAverage throughput/overflow flow rate [m3/s/m]uc

Critical flow speed soil protection [m/s]hbiInland water level in relation to NAP [m]hbb

Height top soil protection [m NAP]

Vc

Maximum volume of storage capacity in the hinterland, with no significant
consequences [m³]Vos/olIncoming volume as a result of transhipment/overflow over the closed
work of art during a high water period [m³]Δhkom

Permitted level increase for storage [m]AkomCompressing surface [m²]ts

Storm duration [s]Under the simplifying assumption that all strength terms in formulas 5.5 and 5.6
are (almost) deterministic, formula 5.4 can finally be rewritten to:

An important load variable in both comparisons is the flow rate qos/ol. Hydra-NL
can be used to determine this. In Hydra-NL the relevant load parameters are
considered as stochastic variables.
71 頁
This is discussed further in section 5.2.
The strength variables Vc and qc/uc are respectively the available storage behind thebarrier and the critical transfer and/or overflow flow rate/the critical flow rate forsoil protection. These are further elaborated in section 5.2.2.
For limit state function 2 (probability of collapse artwork given failure of soil
protection), it is initially assumed that this mechanism always occurs as soon as thesoil protection has collapsed. Tightening of this is possible but requires a specialist
91

consideration that falls outside the framework of this Work Guide. The utilizationof this additional strength, if any, fits in better with assessment than with designs.
It is advisable to deal with this with caution.
5.2

Taxes and occurring transfer and/or overflow flow
The hydraulic loads, in combination with the geometry of the artwork, determine
the flow rate (qos/ol) that flows through wave overtopping and/or overflow over theflooded closed artwork. For the taxes this concerns a combination of water levels
and wave heights on the outside. These can be determined with Hydra-NL for the
failure mechanism. The water level course also plays a role in being able to calculate
the available storage space back to a critical transfer/overflow flow rate that can beused in Hydra-NL to determine the required height or failure probability at a given
height.

5.2.1

Combination of water level and waves
The occurring transfer/overflow flow rate is always determined by a combination ofwater level and waves. A high water level with small waves can give the same
overtopping/overflow as a lower water level with very large waves. Data on thiscombined statistics of water levels and waves can be derived from Hydra-NL.

5.2.2

Water level course outside water
The course of the flood wave in time also determines how much water can flow inover a closed artwork during a flood. This volume of incoming water is important tobe able to assess whether the storage capacity is exceeded. This will be discussed in
more detail in the chapter on the storage of coffers (chapter 10).

5.2.3

Occurring transfer and/or overflow flow
This section gives the formulas that are included in the Hydra-models to determine
the occurring transfer/overflow flow. These formulas are valid for vertical walls on
relatively deep water (wave height just before the construction does not exceed
about 1/3 of the water depth) and no heavy wave breaking occurs just before theconstruction. For vertical walls with a foreshore on which the waves adapt,reference is made to Section 5.5.

72 頁
When calculating the transshipment/overflow flow, three situations are92

distinguished:
1. Outdoor water level <turning height artwork: only wave overtopping
2. Outdoor water level> deflecting height artwork AND no or off-shore waves:
overflow
3. Outdoor water level> deflecting height artwork AND waves: combination
formula for wave overtopping and overflow
5.2.3.1. Golf conditions
To make the transition from onshore to offshore waves gradual, an influence factor
Ys is used in Hydra-NL (and Riskeer):

with:

and:

Here is:Hm0

Significant wave height after correction with influence factor [m]; thisis the wave height used to calculate the overtopping flow

γs

Influence factor offshore waves [-]Hm0, input Significant wave height in illustration point Hydra-NL calculation [m]βAngle of wave attack [°]θ

Wave direction [°]ψNormal of the artwork [°]5.2.3.2. Situation with wave overtopping only
The formula for the inflow rate as a result of wave overtopping is (see formula B2.4
from the Guidance for Art Works 2003 ([Ref.5.5])):

with:
93

Here is:qos

Average throughput over a vertical wall [m³/s/m]mosModel factor for transshipment flow = 0.13 [-]g

Gravitational acceleration (9,81) [m/s²]______________________________
20

This formulation differs slightly from [Ref. 5.5] and [Ref. 5.6], where it is stated that γβ= 0 if β> 90 °. This was done to allow the transition from onshore to off-shore waves toproceed gradually______________________________
73 頁
Hm0

Significant wave height after reduction with influence factor Ys [m]hLocal outdoor water level compared to NAP [m]hkhTurning height artwork compared to NAP [m]βAngle of wave attack [°]. This is the angle between the wave direction
and the normal of the artwork.

γnInfluence factor nose construction [-]γβInfluence factor skew wave attack [-]A nose construction can be fitted to limit the occurring transfer/overflow flow. Thisis hardly the case with artworks. The influence factor Yn for a nose construction is
not included in Hydra-NL (and not in Riskeer). The formulas for calculating theinfluence of a nose construction on the transshipment flow rate can be found insection B2.4.1 of the Guidelines for Art Works 2003 ([Ref.5.5]). For a method tosubsequently translate this influence to a required crown height, reference is madeto Section 7.3.6 of the Scheme for height of work of art ([Ref. 5.4]).
In the Guidelines for Art Works 2003 ([Ref.5.5]) an additional wind factor Yw isapplied if small transhipment rates occur (qos ≤ 10 l/s/m). Because such smalltranshipment rates are rarely used in the design of works of art, the backgrounds
will suffice with a reference to the Guidelines for Art Works 2003 [Ref. 5.5] and the
Background Report keyboard track Height I - Modeling overflow/overflow flowrate ([Ref 5.6]).

94

5.2.3.3. Situation with overflow only
If the artwork is closed high water, there is no direct contact between inside andoutside water. The inland water therefore has no influence on the size of the
inflowing flow. The overflow formula is therefore also derived from a situation witha complete spillway:

Here is:qol

Overflow flow over a vertical wall [m³/s/m]molModel factor for overflow flow rate [-]The factor m varies depending on the radius R of the crown and theoverflow height H:
a. the maximum value of mol is 1.3 at R/H = 0.6 to 2; for larger R/Hm decreases; at R/H = 6 approaches mol to 1 (one long spillway);b. for R/H <0.6 the flow is released and mol also decreases;c. for a sharp, aerated spillway (R/H = 0) m also approaches 1, provided
that the overflow height is much smaller than the upstream water depthor the width of the jet is much smaller than the upstream width. Usually
a value of 1.1 is used for mol.

gGravitational acceleration (9,81) [m/s²]hLocal outdoor water level compared to NAP [m]hkhTurning height artwork compared to NAP [m]74 頁
5.2.3.4. Situation with both wave overtopping and overflow
The formula for the inflowing flow if there is both wave overtopping and overflow(see formula B2.17 from the Guidance for Art Works 2003 ([Ref.5.5])):Here is:qos + ol

Average transfer and overflow rate over a vertical wall at the same timeoccurrence of transhipment and overflow [m³/s/m]molModel factor for overflow flow rate [-]. Usually a value of mole is given formoles 1.1, see explanation in section 5.2.3.3.

gGravitational acceleration (9,81) [m/s²]95

hLocal outdoor water level compared to NAP [m]hkhTurning height artwork compared to NAP [m]mosModel factor for transshipment flow = 0.13 [-]Hm0

Significant wave height after reduction with factor Ys [m]5.2.3.5. Overarching formula
The above can be summarized in the following formula:

Here is:qos/olCombined average throughput and overflow flow rate over a vertical wall
[m³/s/m]

5.2.4

Wave overtopping as a non-stationary phenomenon
The critical transfer rate is a time average. In reality there is no question of aconstant flow, but per incoming wave a quantity of water goes over the structure
and then again for some time nothing. These transshipment amounts per wave
depend on the wave height and the distance between the water level (stagnant
water line) and the deflecting height. The greater the wave height, the greater thequantities per overtopping wave at the same average overtopping rate. This aspect
must be taken into account when determining the critical transhipment rate inconnection with the strength of the soil protection. For determining the inflow
volume for cup storage, only the time-averaged transfer/overflow flow rate isimportant and this aspect does not play a role.
A relationship was established between the wave height and the average flow rate in
EurOtop 2016 ([Ref 5.3]). It must be remembered that:This is particularly important for works of art where the transhipment rate
directly taxes the soil protection (especially denominations). For works of art
where the transhipment flow in a body of water ends up behind the artwork,
the volume per wave is much less important.



The verification for the high water situation involves a process of ongoing
erosion of soil protection. Incidental/local damage as a result of a single outlier
in the transshipment volume does not necessarily lead to failure (but can ofcourse be of importance for other functions).

96

75 頁


All available formulas to determine the critical strength of the soil protection
are based on a time-averaged flow rate at the location of the soil protection.

All in all, there are hardly any handles for the designer to determine the maximum
permissible volume per individual wave. As a rule of thumb, it can be maintainedthat at a large wave height (for example, greater than 3 m), the lesser average
critical wave overtopping flow must be maintained for the erosion mechanism.
Some guidance can then be found in section 3.3 of EurOtop 2016 ([Ref 5.3]).
With overflow the phenomenon is much more stationary and large constant flows
can occur. In case of mainly overflows in combination with wave overtopping,incidental outliers in the transshipment flow are also of secondary importance.
5.3

Strength
The strength of a work of art with regard to height consists of four parts:
1. The geometry of the work of art: the deflecting height and width of thehigh-water retainers and the adjacent structural parts determine the load on thesoil protection (the inflowing flow rate Qos /ol) and the cup storage (the inflowing
volume Vos /ol).
2. The characteristics and scope of the available storage capacity of the underlying
water system (Vc) (see chapter 10 Bowl storage).
3. The structure and dimensions of the soil protection behind the artwork.
4. The structural strength of the turning means.
The above components are reflected in formulas 5.5 and 5.6 for the determinationof the failure probability for transhipment and/or overflow and are explained in
more detail in the paragraphs below.

5.3.1

Turning height and width of the artwork
The deflecting height of the high-water retainers and the adjoining water-retaining
structures determine the transfer/overflow flow that flows in per linear meter over
the work of art. Their width then determines the total flow that flows in over theclosed work of art. Adjacent construction parts where the spill/overflow water also
ends up behind the work of art and the soil protection or the cup storage must also
be taken into consideration.
97

The width of the artwork is actually always a given from the other function (s) of
the artwork. The required deflection height can be determined with Hydra-NL (seesection 5.4). The schematization of the width plays a role here. Usually the width tobe maintained is equal to the width of the reversing means. If the adjacentstructural parts have more or less the same height as the reversing means then thismust be taken into account. Instructions for this can be found in section 7.3.6 of
the Schematisation guide for tall works of art [Ref. 5.4].
5.3.2

Bowl storage
For the purpose of determining the required deflecting height, the composting
capacity must be converted to a flow rate per linear meter over the reversing means
and adjacent structural parts. (76 頁)From conversion of formula 5.6 follows that
there is just no question of failure if:

Here is:qos/olAverage transhipment/overflow flow over the artwork per linear meter[m3/s/m]Akom

Compressing surface [m²]Δhkom

Permitted level increase for storage [m]tsDuration of high-water wave [s]B

Width of the artwork [m]The method of determining the parameters Akom, Δhkom and ts is discussed in thechapter on Reservoir Storage (chapter 10). The parameter B is in the above section
5.3.1.
It should be noted that the above formula is based on a schematisation of the highwater wave as a block with a constant duration. For systems with a 'short' load
duration (coast, lakes) this is usable, for systems with a long-term load (rivers,deltas) not. For these systems, the output of the Water Level Gradient tool must be
used to correctly determine the inflow volume. For more information, please referto the chapter 'Reservoir storage' (chapter 10), for practical application to thechapter Case study (chapter 11).
98

5.3.3

Soil protection
The strength of the soil protection can be converted to a critical flow rate per linear
meter over the reversing means and adjacent structural parts for the determinationof the required deflecting height. After all, conversion of formula 5.4 follows that
there is just no question of failure as:

Here is:q os/ol

Average transhipment/overflow flow over the artwork per linear meter[m3/s/m]uc

Critical flow speed soil protection [m/s]hbiInland water level in relation to NAP [m]hbb

Height top soil protection [m NAP]

Bsv

Power-carrying width soil protection [m]B

Width of the crown of the artwork [m]The critical flow rate of soil protection is often known from the design of the otherfunction (s) of the artwork. If this is not the case, then this critical flow rate can be
determined on the basis of the Soil Protection chapter (chapter 9). The parameters
hbi and hbb speak for themselves and are also discussed in the Soil Protection section.
The parameter B is discussed in section 5.3.1.
77 頁
5.3.4

Maximum transhipment flow from a constructive point of view
It is recommended that the critical flow rate from both soil protection and storage
should not exceed 0.1 to 1.0 m3/s/m. This is a rule of thumb; at a flow rate of 1.0
m3/s/m, a water disc of about 0.6 m over the deflecting parts of the structure enters
the overflow situation. With such inflowing flow rates, dynamic aspects as a resultof air inclusions under the overflowing jet may play a role. Larger flow rates are
permissible provided that the stability of the retaining components is thendemonstrated.

5.4

Determine required turning height
The required turning height of the artwork can be determined with Hydra-NL (and99

in the future also with Riskeer). Both methods are briefly explained below.
5.4.1

Determine the required height with Hydra-NL
In Hydra-NL, the required crest height can be calculated directly for view years
2023, 2050 and 2100 (for other view years, it must be interpolated or extrapolated).
Here, the smallest critical flow rate qos/ol resulting from the partial-track storage(see formula 5.16) and soil protection (see formula 5.17) is entered in the program.
Note: this concerns the flow per linear meter barrier! The failure probability insection 5.1.4.1 is also entered. Hydra-NL then calculates the hydraulic load level
HNB, or the required deflecting height, where the sum of the probability ofoccurrence of all combinations of water levels and wave heights leading to
exceeding the imposed overtopping flow is equal to the failure probability. To thisend, a vertical wall module is included in Hydra-NL with the formulas as included
in section 5.2.3. In the case (chapter 11) this working process is explained in moredetail and the relevant input screens are provided with a brief explanation.
The critical transhipment flow is introduced in Hydra-NL as a deterministic
parameter. With this, Hydra-NL deviates from Riskeer. Also the hydraulic loads arederived in Hydra-NL in a slightly different way than in Riskeer. This means thatthe calculated crest heights with Hydra-NL for visual year 2023 can deviate only
slightly from Riskeer (order 0.1 m).

5.4.2

Determine the required height with the help of Riskeer
In Riskeer a fully probabilistic calculation is performed. The method of calculationis (obviously) aimed at the assessment of existing works of art whose geometry isfixed. With the deflecting height as one of the input parameters, a failure
probability is determined. Through an iterative process, the turning height can be
determined in Riskeer, where the artwork meets the failure probability. For the way
in which the various parameters must be schematized and introduced in Riskeer,
reference is made to the WBI toolkit.
It should be noted that Riskeer is still set up as an assessment instrument at thetime of writing this work guide; it is not equipped as standard to work with statistic
files that take account of climate developments. It is expected that the functionalityof Riskeer will eventually be made suitable for designs.

78 頁
100

5.4.3

Sharper determination of throughput
The occurring transshipment/overflow flow rate is determined both in Riskeer andin Hydra-NL on the basis of the formulas from the Guidelines for Art Works 2003([Ref.5.5]). Since 2003 knowledge development has taken place in this area,
making it possible to determine the transhipment rate more sharply21. The mostrecent knowledge on this subject is laid down in EurOtop 2016 ([Ref 5.3]). Section
5.5 shows how EurOtop 2016 ([Ref 5.3]) can be used to determine the requiredcrown height more sharply.

5.4.4

Construction height calculation
When determining the installation height of the crown, the following surcharges
must be taken into account at the calculated crown height:

A surcharge for outdoor oscillations, pipe fittings and seiches.

A surcharge for (local) noise if not already included in the water level statistics.



The locally expected subsidence over the plan period.

The expected curvature due to settlement of the subsurface over the planning
period, after completion.

The high water rise over the planning period is already included in the Hydra-NL
calculation.
For the determination of the surcharges for external oscillations, pipe fittings,
seiches and local windings, see chapter 3 Hydraulic loads.
5.5

Relationship with the EurOtop manual

5.5.1

When to use EurOtop?
EurOtop 2016 ([Ref 5.3]) has a broader scope than the formulas for determining
the transshipment/overflow flow rate in section 5.2, which originate from the
Guidelines for Art Works 2003 ([Ref.5.5]). The formulas in section 5.2 are inprinciple intended for a vertical wall on relatively deep water (no heavy wave
breaking for the construction). EurOtop 2016 ([Ref 5.3]) is more widely applicableand can also be used to determine the required crown height if there is no verticalwall on relatively deep water.
With non-breaking waves for the construction, it is not necessary to use
EurOtop2016. As can be seen from Figure 22, the formulas from the Guidelines for101Art Works 2003 - and which are also used in Riskeer and Hydra-NL - are somewhat
conservative with respect to the formulas from EurOtop 2016 ([Ref 5.3]).
EurOtop2016 can be used in this situation to achieve a sharper design. The 'gain'that can be achieved with this is order 0.1 to 0.2 times the wave height in the part of
the graph where most constructions lie (freeboard between 0.5 and 1.5 times thewave height).
If there are waves of refraction for the artwork, then the formulas in the 2003
Guideline Art Works (see section 5.2), especially for larger freeboards22, are notalways conservative. It is recommended in that case to explicitly verify whether it isnecessary to use EurOtop 2016 to determine the required crown height.
______________________________
21

In [Ref. 5.6] the background is included why the decision has been made to continue to

use the formulas from the Guide to Works of Art 2003
22

Height of the crown above the local still water level______________________________(79 頁)Figure 22 can hereby be used as an aid.

※（Rijkswaterstaat, Central government 2018）79 頁より作成。
Figure 22 Overview formulas in graphic form for vertical constructions from EurOtop 2016
and Guide to Works of Art 2003. The freeboard (Rc) is the height of the crown above the102local standstill level. Base: figure 7.5 from EurOtop 2016.
5.5.2

Dealing with different construction forms in EurOtop 2016
With the help of EurOtop 2016, the transshipment flow rate for a range ofcomposite constructions can be calculated. For the design of water-retaining
structures, the spill overflow in vertical constructions (Chapter 7 from EurOtop
2016) is particularly important. For vertical walls, EurOtop 2016 distinguishes
between three situations:
1. Vertical walls on relatively deep water. The waves hardly change due to depth
limitation. This is by far the most common among flood defense structures.
2. Vertical walls with a front bank on which the waves adapt. This situation rarely
occurs with works of art. Depending on the water depth for the construction andthe steepness of the waves, breaking or non-breaking waves occur against thevertical wall.
a) Non-breaking waves can reach the top of the structure and then transfer,similar to vertical walls on deep water. The transhipment formula also
resembles that for vertical walls on deep water, but the transhipment flow isslightly higher.
b) Breaking waves against the construction go high into the air after which a partpasses over the construction. This situation always gives wave overtopping
regardless of the height of the barrier.
The occurring transhipment rates per meter width for the cases 1, 2a and 2boutlined above are given in Figure 22. The corresponding formulas are given inparagraph 7.3.2 of EurOtop 2016. (80 頁)Please note: for the design, the formulas
associated with the so-called 'design approach' must be applied in EurOtop 2016.
This concerns formula 7.2 for situation 1 and formula 7.6 for situation 2a. Formulas
7.9 and 7.10 apply for situation 2b. In addition, various formulas for composite
constructions have been included in section 7.3.3 and further.

5.5.3

Tax statistics when using EurOtop-manual
When using the formulas from EurOtop 2016 to determine the required height of
the artwork, the required height is always a function of the wave height and theovertopping flow. The transhipment flow follows from the considerations regarding103

storage and soil protection. However, a wave height must also be entered.
For this, the illustration points from Hydra-NL can be used. Although the formulasfrom the Guide to Art Works 2003 have slightly different coefficients, they areexactly the same as the formulas from EurOtop 2016. Therefore it can be expectedthat the illustration point of a calculation with Hydra-NL would have been the sameas the formulas from EurOtop 2016 would have been included. Therefore, a first
calculation can be made with Hydra-NL. In case of any tightening on the basis of
EurOtop 2016, the required wave height can be obtained from the illustration pointof the Hydra-NL calculation (take the wind direction with the largest probability
contribution). This is worked out in more detail in chapter 11 Case.
5.6

Concrete design recommendations height artwork
When designing a work of art, a number of choices can be made that cansignificantly reduce the chance of failure. A number of choices are mentioned
below.
First of all, it is good to realize that designing the required deflecting height often
does not have to take place at the sharpest point of the cut. The application of alittle extra height is in fact relatively inexpensive.
In the design of a new work of art, it may also be wise not to fully utilize the claim
to the available storage space. In any case, the developments that occur in the water
system over time must be taken into account. Because artworks often have a longdesign horizon (100 years is common) it is impossible to predict the developmentsin the water system for this period. It is therefore advisable not to load the cup
storage as much as possible so that some margin remains in the underlying system.
Particularly for denominations where the foreland is the same as that of theadjacent dike body, it makes little sense to make the height of the artwork higher
than the height of the adjacent dike body. However, it is important to ensure an
expandable construction and to take account of degradation and higher future loads
when dimensioning structural elements. After all, the dikes are usually designed ona shorter planning period.

81 頁
104

5.7

References and background documents[Ref. 5.1] Bree, B. van, WTI 2017 Key rules for works of art - Test track report
Height, Deltares, 1220087-001-GEO-0010, Version D1, December
2015[Ref. 5.2] Guide to Design with Flood Opportunities - Safety Factors and Loads
for new Flood Risk Standards, version OI2014v4, Rijkswaterstaat WVL,
February 2017
[Ref. 5.3] EurOtop - Manual on wave overtopping or sea defenses and related
structures, Second edition, Pre-release October 2016
[Ref. 5.4] WBI2017 - Schematisation manual for height of artwork,
Rijkswaterstaat WVL, version final, January 2, 2017
[Ref. 5.5] Guide to Works of Art 2003, TAW, May 2003
[Ref. 5.6] Bree, B. van, WTI 2017 Works of art Background report of the exam
track Height I - Modeling overflow/overflow flow rate, Deltares,
1220087-001-GEO-0004, Version D1, December 2015
[Ref. 5.7] Regulations for primary flood defenses 2017 - Appendix III Strengthand safety, Ministry of Infrastructure and the Environment

105

83 頁

6

Piping

6.1

Introduction

6.1.1

Introduction failure mechanism
Underneath a structure, concentrated seepage streams can be formed, resulting inleaching of material from the subsurface. In this chapter handles are given tocontrol this problem.

6.1.2

Phenomenological description
A detailed description of the failure mechanism for piping can be found in Chapter
4 of the WBI Test Track Report Piping [Ref. 6.1].
In the event of failure by piping, hollow pipe-like spaces under (underflow) or
around (backward running) create a work of art through the rinsing of soil particles
as a result of a concentrated seepage stream. If this erosion process does not stop in
time, the artwork can collapse.
By "backwardness" is meant the formation of channels or hollow spaces on theside of a work of art as a result of the rinsing of soil. The normative seepage
route is usually purely horizontal (a seepage flow along the structure at theinterface of a cohesive layer), but can also contain vertical components (think ofan entry or exit point under a wing wall). In practice, however, backwardness isoften linked 1 to 1 to situations with a purely horizontal seepage path.
Substance concerns the creation of cavities under a work of art as a result of aconcentrated seepage stream in which soil particles are entrained. Here, theseepage flow passes underneath the work of art on the interface between
construction and sand. Quarry screens are usually present underneath a work ofart, as a result of which the seepage flow also includes vertical components.
However, this does not always have to be the case. Think of long divers andpipes where no seepage screens are present. In practice, however, underflow isoften linked 1 to 1 to situations with a (partially) vertical seepage line.
In line with the WBI2017, the Lane and heave models can be used in situations
where the seepage line contains one or more vertical components. For situations
106

with a purely horizontal seepage path, the models of Bligh23 and Sellmeijer areavailable (for works of art). In Figure 2-3 of the schematization manual Piping
works of art [Ref. 6.3] a more detailed overview is included in which situation the
different models apply. A detailed description of these models can be found inchapters 5 and 6 of the WBI test track report Piping [Ref. 6.1]. The models areconcisely summarized in section 6.1.3.
______________________________
23

This differs from the Sand-bearing Wells Research Report [DLT-ozw 2012], in which it isrecommended that Bligh's model should no longer be used. However, this recommendationis entirely based on research carried out for dikes. Because works of art due to the presenceof seepage screens have a different groundwater flow image than dikes, it has been decided
to maintain Bligh's model for the time being when testing and designing works of art. This ispartly due to the lack of suitable calculation models that can replace the Bligh model.
______________________________
84 頁
In verifications of under- or back-running, the strength is often expressed as a
critical decay. The critical decay is defined as the decay where no continuous pipe
is created below or next to the artwork. Before the artwork as a whole succumbs
after exceeding the critical decay, a number of follow-up processes have to becompleted. After the creation of a continuous pipe beneath or next to the work ofart, such an erosion of soil material must occur that the overall stability of theartwork is insufficient. This can be done by tilting or shifting the entire work of art,or by a process in which successive parts of the work of art collapse structurallywith the collapse of the total work of art as the final result. It is also possible thatthe artwork remains standing, but the adjacent dike collapses as a result of theerosion process and eventually collapses. A considerable residual strength is often
still present after exceeding the critical decay. This is charged through the rightbranch of the failure tree in figure 23.
However, concrete models are lacking to quantify the residual strength and to
express it in a chance of failure of the artwork as a whole after the critical decay has
been exceeded. Therefore, residual strength is rarely taken into account in practiceand the chance of exceeding the critical decay determines the probability of failureof the artwork as a whole. Incidentally, it is also recommended for designs not totake any residual strength into account anyway. For assessment, taking alongresidual strength may be relevant.
107

Failure hydraulic structureby pipingAND

Occurrence of under and/or
backwardness (1 and 2)

Succumbing hydraulicstructure as a result of under
and/or backwardness (3)OR
Occurrence of under and/or
backwardness, seepage (inpart) verticallyOccurrence of under and/or

rear running, which is purely
horizontal※（Rijkswaterstaat, Central government 2018）84 頁より作成。
Figure 23 Failure tree failure mechanism piping
85 頁
Figure 23 shows that failure of the flood defense occurs when:(1) presenting a high waterAND(2) As a result of a concentrated seepage flow such(a) Leaching of soil particles under (underflow) or(b) Around (backwardness) the artwork is created that creates acontinuous erosion channel (pipe).

AND(3) The artwork collapses due to this piping with substantial
damage and/or casualties (flooding) as a result.

In section 4.2 of the WBI test track report Piping [Ref. 6.1] a more detailed
description of the above failure process is included.
6.1.3

Safety format and concise model descriptions
The starting point of the safety format is the requirement that the failure
probability for piping Pf, KW, PI is less than or equal to the failure probability forpiping Peis, KW, PI or:

108

6.1.3.1. Determination of failure probability
The failure probability is derived from the legal requirement for the standard routeand can be determined with the aid of the following formula:

In which:
Peis, KW, PI

Failure Chance for piping an individual artwork for a reference
period of 1 year [-]Pmax

Failure Chance for the entire dike section (standard route) basedon the maximum permissible probability of flooding from thewater act24 [-]ωPI

Failure probability factor for piping [-]NPILength effect factor for piping [-]In the standard failure probability distribution for a standard trajectory as includedin the WBI2017 and the OI2014v4, a value of 0.02 is used for the probability of
failure of the piping (ωPI). Deviation from this is possible but rarely occurs inpractice. See the chapter on Design Verifications (chapter 2).
An upper limit of the length-effect factor NPI can be obtained by making it equal to
the number of structures in the dyke section where piping is a relevant aspect.
Because the probability of failure per artwork is rarely identical, a maximum of NPI= 10 is recommended in the OI2014v4. For a more accurate estimate of the length
effect, the failure probabilities for piping of the other structures can be consideredin the range. Among other things VNK2 results can be used for this.
___________________________
24

This is referred to as the lower limit in the Water Act___________________________(86 頁)In addition, sufficient margin must be maintained when determining the N value inorder to be able to absorb future changes within the process, such as theconstruction of more works of art in the process. If the available chance of failure
for the new artwork to be designed is too small, then the options are as follows:1.

Adapt the failure probability budget, so that the failure probability factor for
piping in artworks becomes larger.
109

2.

Create extra chance of failure through improvement measures for the otherstructures in the dyke section.
The latter is not very obvious because in many engineering works
improvement measures will be necessary to adjust the failure probability
substantially (e.g. by a factor of 5-10).

Lack of relationship between safety factor and probability of failure for Bligh, Laneand heave models
For Bligh, Lane and heave models, there is as yet no explicit relationship between
the calculated safety factor and the probability of failure. The failure probability ispresumed to be met if the barrier conforms to these models at an outside waterlevel that is equal to the water level at the standard. Data for a semi-probabilistic
design verification (WBI) is only available for the Sellmeijer model. In thefollowing sections the safety format is discussed for the individual models.
6.1.3.2. Safety format and model descriptions Bligh and Lane
For Bligh and Lane models, it is unclear how reliable a flood defense is when it isapproved or designed with one of these rules. Within the VNK2 project, aprobabilistic approach to both models was introduced at the time. The propertiesof the stochastic variables in both models are estimated on the basis of expert
judgment. Based on this, semi-probabilistic calculation rules for both Bligh andLane were derived in the WBI. In this Work Guide, however, it was decided toconnect with the choice made in the WBI not to count (semi-) probabilistic withthese models.
In both models it is verified whether the calculation value of the occurring decay on
the artwork ΔH (the load) is smaller than the calculation value of the critical decay
ΔHc on the artwork (the strength):

The calculation value of the occurring decay is the decay with an exceedance
probability that is numerically equal to the maximum permissible flooding
probability.
The calculation value of the critical decay ΔHc over the artwork is calculated
according to the Lane model as follows:
110

87 頁
According to Bligh's model, the critical decay ΔHc over the artwork is calculatedusing formula 6.5:

If a crack channel is present through which sand must be discharged outside, thefluidized sand in the channel will provide extra resistance. On the basis of tests by
Sellmeijer (1981), the Technical Report Sand Meering Wells [Ref. 6.10] proposes
the following correction to the Bligh model if a burst channel is present:

Here is:
ΔHc

Critical decline over the artwork [m]ΔHPresent decay on the artwork [m]LvTotal length of the vertical parts of the seepage line [m]LhTotal length of the horizontal parts of the seepage line [m]CcreepCreep factor from Bligh (material constant of the substrate) [-]Cw, creep

Weighted creep-factor of Lane (material constant of the subsurface) [-]In Table 7 the values given by Bligh and Lane are for different types ofmaterial in the soil layer. These values can be understood as calculation
values.

dLength of crack channel [m]Table 7 Creep factors (nominal values) for the Lane and Bligh rules
Soil typeMedian grain
diameter [μm]Extremely fine sand, silt
Very fine sand< 105

Cw, creep

Ccreep(Lane)(Bligh)8,5105 – 150

Very fine sand (mica)
Moderately fine sand1

150 – 210
111

18
7

18

7

15

(quartz)
Moderately coarse sand

210 – 300

6

Very/extremely coarse sand

300 – 2000

512Fine gravel

2000 – 5600

4

9Moderately coarse gravel

5600 – 16000

3,5> 16000

3

Very coarse gravel

4※（Rijkswaterstaat, Central government 2018）87 頁より作成。
1

Indications in accordance with NEN 5104 (September 1989)

6.1.3.3. Safety format and model description heave model
For engineering works - in contrast to dikes - only a deterministic verification isavailable. Here it is verified whether the calculation value of the occurring
displacement over the downstream seepage screen i (the load) is smaller than (acalculation value of) the critical displacement ic over the downstream seepage
screen (the strength):
88 頁

In the deterministic calculation, the calculation value ic;d = 0.5 is maintained25.
When checking heave, it is thus checked whether the calculation value of theoccurring displacement over the downstream seepage screen is smaller than thecritical vertical displacement ic,d of 0.5. It should be noted that this value isgenerally regarded as sufficiently safe, but that further substantiation is still lacking
for the time being.
6.1.3.4. Safety format and model description model of Sellmeijer
For the Sellmeijer model, a semi-probabilistic method is available. The
determination of the failure probability is discussed in section 6.1.3.1. Below wewill discuss the determination of the probability of failure with this model.
Determination of failure probability
The failure probability for piping Pf, KW, PI follows from the failure tree in Figure 23.
Herein are the distinguish the following three partial failure mechanisms:1.

Occurrence of under and/or backwardness, seepage (partly) vertical (limit
112state function ZPIP1)
2.

Occurrence of under and/or backwardness, seepage path purely horizontal(limit state function ZPIP2)

3.

The total collapse of the artwork after under and/or rear running has takenplace (limit state function ZPIP3)The Sellmeijer model may only be used for purely horizontal seepage roads in one
direction. This means that limit state function ZPIP1 is not relevant here.
For limit state function ZPIP3 (collapsing artwork in the event of occurrence ofunder/or rearward running), it is initially assumed that collapse of the artwork
always occurs as soon as there is under and/or backward running (P (ZPIP3 <0) =1). Tightening of this is possible but requires a specialist consideration that falls
outside the framework of this Work Guide.
For limit state function ZPIP2:

Here is:
ΔHc

Critical decay as calculated using the Sellmeijer model [m]ΔH

Emerging decay on the artwork [m]dThickness of the covering layer [m]___________________________
25

This calculation value for the critical relocation is higher than for dikes. The difference

between heave behind a seepage screen and heave over a covering layer is that with aseepage screen there must always be a vertical path due to the sand present. This requires
fluidization of the sand package downstream of the seepage screen, for which the required
gradient is approximately 1. A safety factor of approximately 2 has been applied to this,resulting in a critical gradient of 0.5. With a cover layer, the resulting crack is filled with aliquid sand-water mixture: in principle, this crack is almost never completely filled withpacked sand. As a result, the water velocity through the cover layer can become so large thatthe hole is more or less flushed, which results in a smaller critical ratio of 0.3.
___________________________
89 頁
The strength variable ΔHc is determined using the Sellmeijer model. The model of113

Sellmeijer is described in paragraph 7.3 of the Research Report Sand Meandering
Wells ([Ref 6.5]). The updated version included in the WBI2017 is as follows:

Here is:L

Pathway (measured horizontally) [m]Fresistance Resistance factor, describes the boundary balance of grains of sand on thesoil from the pipe [-]Fscalescale factor, reflects the ratio between the process scale of the mechanism
for pellet transport and the process scale of the groundwater flow thatdrives this transport mechanism [-]Fgeometry Geometry factor, describes the influence of the shape of the geometry of
the subsurface on the groundwater flow [-]. The formula presented isvalid for a standard configuration with one homogeneous sand layer below
it impermeable work of art. With a deviating geometry, the factor must be
Fgeometry are determined with the piping module from the groundwaterflow model MSeep.
Y'p(Apparent) volume weight of the sand grains under water [kN/m3] = Yp Yw with Yp = 26 kN/m3 and Yw = volume weight of water [kN/m3]

θRoll resistance angle of the sand grains (θ = 37) [°]η

Coefficient of White (η = 0.25) [-]κ

Intrinsic permeability of the piping-sensitive/upper sand layer [m²]= κ = ν ∙ k/g
k = specific permeability of the piping-sensitive/upper sand layer [m/s]v = kinematic viscosity of water at 10 °C (v = 1.33 · 10-6 m2/s}
g = acceleration of gravity (g = 9.81 m/s2)

d70

70 percentile value of the particle size distribution [m]
114

d70m

Average d70 of the sand types used in the small scale tests, on which thisformula is fitted (2.08 ∙ 10-4) [m]D

Thickness of the sand package [m]Remarks relating to the application for works of art are included in Chapter 6 of the
Test Track Report piping for works of art [Ref. 6.1].
90 頁
When determining the critical decay, use should be made of characteristic values(5% and 95% fractiles) for the input parameters where applicable.
Safety factors
In the semi-probabilistic design verification, the following safety factors must be
applied to the critical decay:

γpip

Safety factor for the failure mechanism piping. This depends on thereliability requirement.

γbPartial factor for the uncertainty about the subsurface and the water (over)voltages (schematization factor)

With this, the verification requirement based on the Sellmeijer model is as follows:

The necessary safety factors are determined as follows:

Safety factor piping
The safety factor for piping γpip that is used in the Sellmeijer model isdetermined using the following formula 6.14:

rin is:βeis, KW, PI

Reliability index associated with the failure probability Peis, KW, PI
(-):
115

βmax

Reliability index associated with the maximum permissible floodprobability

Φ-1

Inverse of the standard normal distribution

Schematization factor γb
For the determination of the schematization factor γb, the usual method from
[Ref. 6.8].

6.1.3.5. Connection to Eurocode 7
Section 10.5 of the Eurocode 7 briefly discusses the design of measures against
piping. Reference is made here to the old Guideline for the design of river dikes;
part 1-upper rivers area. In addition, a safety factor is specifically introduced for
the Lane model, which varies between 1.5 and 2 depending on the risk class used.
A substantiation of this factor-dependent safety factor is not given in the Eurocode
7. The use of this factor has therefore not been included in this Guideline.
6.1.4

Step-by-step plan for design
Figure 24 shows the steps that are set in the design process. Each step is briefly
explained below in the figure.

91 頁
Step 1
Determine design
decay on hydraulicstructure based onwater level at norm
and inland waterlevel

Step 2
Determine therequired length of
the hydraulicstructure by meansof possible seepage
roads and models

Step 3
Determinedimensions ofnecessary facilities
to prevent piping※（Rijkswaterstaat, Central government 2018）91 頁より作成。
116

Figure 24 Step-by-step plan for design failure mechanism piping
Below is a brief explanation of the steps indicated:
Step 1. Based on the standard of the dyke stretch, the outside water level is determined using
Hydra-NL. For the outside water level, the water level must be adhered to thestandard. Furthermore, the inland water level is determined which is considered
normative for piping. Together, these two parameters determine the decay of theartwork where the necessary measures to prevent piping are explained. This step is
explained in more detail in section 6.2.
Step 2. In this step it is determined which seepage path length is required to prevent pipingwith sufficient certainty. The model with which this is done is determined by the routeof the seepage roads that are possible under and/or next to the work of art. This isfurther elaborated in section 6.3. The models themselves are given in section 6.1.3.2
to 6.1.3.4. Please note: with the Sellmeijer model (see section 6.1.3.4), a safety factor
must be charged that is dependent on the failure probability as determined in section
6.1.3.1. Specifically for the Sellmeijer model, step 2 is as follows:

Step 2a
Determine failure
probability Peis, KW,
PI for piping fromthe water retaining
function

Step 2c

Step 2b
Determine safety
factors γPIP and γb(see section
6.1.3.4)

Determine required
seepage length
hydraulicstructure based on
the Sellmeijer
model taking into
account safety
factors from step 2b※（Rijkswaterstaat, Central government 2018）91 頁より作成。
92 頁
Step 3. As soon as the required seepage length is known, the required dimensions of theprovisions against piping (for example filters and seepage barriers) can be further
117

determined. Because the location and dimensions of seepage barriers also affect thepossible seepage roads below and/or around the work of art, this is an interaction withstep 2. This is discussed in section 6.5.
6.2

Taxes
Piping occurs at high outside water levels, where the gradient over the flood
defense is relatively large. The duration of the high water tax also plays a role. Bothare elaborated below. Waves and current play no role.

6.2.1

Decline on the artwork
The decay is determined by the combination of the outside water level and theinland water level. In the context of this Work Guide, only a load combination isconsidered that is related to high water conditions. Note that the decay of theartwork from other functions (e.g. management and maintenance) may be decisive.
The design value of the outside water level must be determined on the basis of thewater level with an (annual) exceedance probability that is numerically equal to the
maximum permissible flooding probability. This water level can be determinedwith the help of Hydra-NL (water level).
For the inland water level, a characteristic low value that fits the high water
situation must then be taken into account. It should be borne in mind that this is
influenced by the water level management just before and during high tide and theorientation of the inland waterway. In designs, any reductions in water level within
the design lifetime must be taken into account. At the same time, the influence ofnoise and dust on the design level in the various design situations must also betaken into account.
In addition to hydraulic loads, no other loads (such as traffic loads, for example)
play a role in the failure mechanism of piping.

6.2.2

Suspension over downstream seepage screen
In a design verification with the heave model, it concerns the transfer over thedownstream seepage screen. A groundwater flow analysis is required for thedetermination of the occurring precipitation. In principle this can be done with any
suitable calculation model. Most common are:118

Calculation using a (multi-purpose) computer program for numericalgroundwater flow analysis, based on a finite element or finite difference
method (EEM or EDM).

Calculation with a semi-analytical calculation model (fragment method). Thismethod has been developed in TAW (now ENW) framework, specifically forheave inspections at dikes or flood defense structures with vertical seepage
barriers.

Reference is made to paragraph 5.4 of the Test Track Report piping for works ofart [Ref. 6.1] for a more detailed description of the heave model and the fragment
method.
93 頁
6.2.3

Time dependency of the load
For a flooding caused by the piping phenomenon, the driving force that triggers theerosion process must first build up and then remain present for a longer period oftime so that the piping process can take place completely. The duration of the load
influences the development of the water stresses in the water-bearing and pipingsensitive layers below and next to the artwork:In the case of 'long' duration water levels, there is stationary groundwater flow.

With water levels of 'limited' duration, there is non-stationary groundwater flow,or time-dependent groundwater flow.

In the case of non-stationary groundwater flow due to short-term high water, thewater tension in the aquifers below and behind the dike is less high at the sameoutside water level than in the case of a stationary groundwater flow due toprolonged high water. This depends on the storage capacity of the soil layers, thepermeability and thickness of the soil layers and the duration of the load. This meansthat with non-stationary flow the force on the granules and with this the chance of
piping is smaller than with stationary groundwater flow. In the estuaries, the lake
district and along the coast the load is storm dominated and thus short-term, whichmeans that there is almost always a non-stationary groundwater flow under highwater conditions. In the upper rivers area the load is depleted and long-term, so thattime dependency hardly plays a role and should be counted as a stationary one. In
the sub-river area there is a combination of storm-dominated (thus short-term) anddischarge-dominated (so long-term) tax. The following applies in general: thefurther downstream, the shorter the tax duration.
119

In order to be able to take into account time dependency, the response of the outside
water level in the water-carrying package must be estimated. Monitoring wellmeasurements can be an important aid here. Because these monitoring wellmeasurements are carried out at lower external water levels, the measurement resultsmust be extrapolated. For the analysis of these measurements and a prediction of the
response, several methods are available, see for example Comparison methods
determination time dependence rise height [Ref. 6.9] and Technical Report Water
tensions at Dikes [Ref. 6.11].
The response of the outside water level in the water-carrying package can also be
calculated using analytical or numerical models. To this end, the Technical Report
Water pressures at Dikes [Ref. 6.11] instructions given. For this, use can be made of
the Water Level Course tool developed in the framework of the WBI2017 for thecourse of the external water level.
6.3

Strength
The strength of the artwork with respect to piping consists of three components:
1.

The length of the seepage roads below and/or next to the work of art.

2.

The characteristics of the soil in which the artwork is founded.

3.

The presence of filter constructions at the artwork.

The first two contribute to the resistance that the groundwater flow under and next
to the artwork experiences. A filter construction does not so much contribute tothis resistance, but prevents soil particles from being entrained as a result ofgroundwater flow. This is explained in more detail in the paragraphs below.
94 頁
6.3.1

Pathway length
The seepage length is directly related to the geometry of the artwork and isdetermined by dimensions of elements along which a seepage flow can occur (seefor example Figure 25). The foundation method of the artwork plays a role in this.
Geometry
The main dimensions of the artwork are usually determined by the primaryfunction (s) of the artwork. The seepage line can then be extended with the aid of120

seepage barriers below and next to the work of art. The required length of theseepage line can be calculated using the Bligh and Sellmeijer models if the seepage
path is purely horizontal, and with the Lane and heave models if the seepage line
contains vertical parts.
With regard to the choice between Bligh and Sellmeijer models, the following
applies:

Sellmeijer's model is intended for horizontal groundwater flow in one
direction. For situations in which there is horizontal groundwater flow in one
direction (i.e., bottom and rear run screens are lacking, for example in pipes
and some box constructions), the situation in structures is completely
analogous to the situation at dikes as long as the construction is properlyaligned with the subsoil. In this situation, the calculation rule of Bligh may not
be applied.

With artworks, however, there are almost always (sub) and rear walk-throughscreens. As a result, the seepage flow is forced to change direction, as a resultof which the seepage path becomes longer and the resistance to piping
increases. This effect cannot be quantified and included in the Sellmeijer
model. The calculation rule of Bligh can be applied for backward running.
Incidentally, the Sellmeijer model can also be used, provided that theadditional seepage length around the rear running screens is left out ofconsideration. However, that is conservative.

If the seepage line contains vertical elements, both the Lane model and the heavemodel can be used. In exceptional cases, Lane's model is not safe enough and theheave model must be applied. These exception cases are described in paragraph 5.5of the Tracking Report on piping for works of art [Ref. 6.1].
Fund method
The foundation method determines whether the part of the seepage line
underneath the structure also contributes to the resistance that the groundwaterflow under and next to the work of art experiences. This is the case for works of art
based on steel. For works of art that are founded on poles or sheet piles, it ispossible that the subsoil will drop, but the artwork will not. This creates a gap
between artwork and subsoil, which greatly reduces the resistance over this part ofthe seepage line. This part of the seepage path then does not contribute to the121resistance that the groundwater flow under the artwork experiences. The
horizontal parts of the seepage line under a pile foundation are therefore notincluded in considerations with the Bligh, Lane and Sellmeijer models.
95 頁
6.3.2

Basis
The resistance that the groundwater flow under and next to the work of art isstrongly dependent on the material of which the substrate consists. In cohesive,
poorly permeable soil layers the groundwater flow is very slow. In addition, themutual cohesion of such soil layers ensures that no soil particles leach out.
Cohesive, poorly permeable soil layers are therefore not susceptible to piping. In
non-cohesive, well-drained soil layers (sand) the groundwater flow is much larger.
In addition, there is no mutual connection between the particles, so that soil
particles can easily be transported through the groundwater flow.
The extent to which non-cohesive soil layers are sensitive to piping depends on thegrain diameter. Two opposite effects play a role in this. The resistance of theindividual grain against leaching increases as the grain size increases. The
permeability of the subsurface, and with it the groundwater flow, also increases
with increasing grain diameter. The first (resistive) effect is, however, stronger, sothat fine-grained materials are more sensitive to piping than coarse-grained. In
Bligh and Lane formulas this is immediately visible because the so-called creep
factor, which is a measure of the ratio between decay and required seepage length,
is greater for fine-grained materials (see Table 7).

6.3.3

Soil protection and filter constructions
On both the in and outflow side of works of art, a bottom defense is almost always
present from the primary function (s) of the artwork. Important are the type of soil
protection (waterproof or water permeable) and the location of the soil protection(on the inside or outside of the artwork). Stamped concrete, colloidal concrete orasphalt mastic are the most common waterproof soil protection systems. Soilprotection constructions that can be regarded as water-permeable are block mats,stone asphalt mats, bricks and granular filters.
Soil protection on the outside of the artwork
If a waterproof bottom protection is present on the outside, then the length of the122soil protection can be included as a horizontal seepage so long as the connection
with the work of art (floor, wing walls, impermeable slope) is good. In the design, it
must be ensured that a good, watertight connection is realized.
A water-permeable soil protection on the outside is of course never included in theseepage length.
Soil protection on the inside of the artwork
A watertight soil protection on the inside of a work of art can only be included in
the seepage length if erosion of this soil protection can be excluded. To this end,
the occurring water pressure under the soil protection must be calculated, after
which it must be checked whether erupting occurs at the calculation value of the
decay. Naturally, the soil protection can be designed in such a way that cracking
does not occur. If the length of the soil protection is taken into account as a
seepage length, the connection with the artwork (floor, wing walls, impermeable
slope) must of course be good.
96 頁
Filter constructions
The bottom protection on the inside can be designed in such a way that it is sandtight and water-permeable. The soil protection can then act as a filter, so thatpiping cannot occur. It must be demonstrated here that during the design life span
the filter remains water-permeable and sand-tight and therefore continues tofunction as a filter.
This is difficult for soil protection constructions on a geotextile. For this reason, it
is recommended that this type of soil protection be considered as clogged andtherefore watertight, unless management measures show that this is not the caseand the soil protection can function as a filter during its life. The length of the soil
protection can be included in a closed-down geotextile as horizontal seepage if it isshown that the soil protection does not erupt.
For filter constructions that are completely granular according to the 'filter rules'(see section 6.5.1), it is likely that the filter effect can be guaranteed during thedesign life of the filter construction. However, it may be necessary to include
specific maintenance measures in the management maintenance plan of the123artwork.
Incidentally, other filter systems can also be included in the design. If these have arole in the prevention of piping, the permeability and sand-tightness of the design
durability must also be guaranteed with sufficient reliability.
6.3.4

Degradation

Various aging mechanisms can influence the resistance of the artwork to piping.
Examples of this are cavity forming under the artwork through settlements,
drawing sheet piles from the construction by negative adhesion, corrosion of steel
screens/rotting of wooden screens, loss of entry resistance due to erosion of thecontiguous soil, etc. The design must be taken into account here by the designer.
This can be done by adjusting the modeling or, where necessary, devising asuitable design solution.
6.4

Schematisation
The search for relevant seepage roads under and/or next to the work of art is thebasis for a good analysis of the probability of the occurrence of piping. The possible
seepage roads are determined by the interplay of geometry of the artwork(dimensions of artwork, seepage barriers, foundation method) and the existing soil
structure.

6.4.1

Geometry artwork
The identification of seepage roads starts with a 3D visualization of the artwork.
With a simple work of art, this analysis can still take place with 2-dimensional tools(longitudinal and cross-sections on the artwork). For more complex works of art(structures with multiple seepage screens and different soil levels), 3D tools should
be regarded as standard.

124

97 頁

※（Rijkswaterstaat, Central government 2018）97 頁より作成。
Figure 25 A three-dimensional elaboration of a complex work of art in Google SketchUp forthe purpose of determining normative seepage roads for under- and back-running (source:Tauw). The figure shows a sluice at an angle from below seen with a seepage line withhorizontal (yellow dotted lines) and vertical (red line) components. It can be seen that the
seepage path continues under the most upstream screen (1), then continues horizontally tothe middle screen (2), this middle screen passes vertically (3) and again after a bit ofhorizontal seepage (4) just next to the downstream screen vertically in the lock chamber (5).
In inventorying potentially relevant seepage roads, both purely horizontal seepage
roads and seepage roads with a vertical component must be considered.
6.4.2

Soil composition under and next to the artwork
In a design verification, the soil structure underneath and next to the artwork isoften known to a large extent. For example, it is known from the design where andwith what material is or will be supplemented next to the artwork. The existing soil
structure can be derived from the available soil survey, supplemented if necessary
with information from the WBI-SOS [Ref. 6.12]. Any missing information canoften be obtained with limited effort.
If several scenarios concerning the soil structure around the work of art are125possible, then each scenario concerning the soil structure has its own chance ofoccurrence. Each scenario then has its own probability of piping. The probability ofa scenario must be estimated on the basis of the available information. The
uncertainty about which scenario is actually present can be covered by theapplication of a schematization factor if the Sellmeijer model is applied (see also
section 6.1.3.4). For the derivation of this schematization factor, reference is madeto Section 3.4 of [Ref. 6.8]. The schematization theory from the Technical Reporton Ground Mechanical Schematisation at Dikes [Ref. 6.8] can serve as an example
in the reasoning of the choice of schematics for an analysis with Bligh and Lanemodels. For a detailed example of its application, reference is made to Section
12.3.7 of Research Report Sand-Liferous Wellen [Ref. 6.5]. Of course, a design canalso be drawn up on the basis of an evidently safe choice for the subsurface. In thatcase no schematization factor needs to be applied.
98 頁
In view of the relatively limited costs of soil research when constructing structures,
further research is always recommended if there are scenarios where theprobability of piping (or another geotechnical failure mechanism) is substantiallygreater.
6.5

Measures to prevent piping
Piping is usually prevented by installing filter constructions or placing seepage
barriers. Both are briefly discussed below.

6.5.1

Installing filter constructions
The failure mechanism of piping can practically be ruled out by providing a filter atthe outlet side of the seepage stream in which outflow takes place. A properly
functioning filter ensures that the water exits in the filter, and that no sandparticles are entrained. To this end, possible exit points of seepage water must havebeen well visualized. The filter must be designed according to the 'filter rules'. For
an overview of these 'filter rules', reference is made to Section 5.4.3 and Section 8.6of the Research Report on Sand-raging Wells [Ref. 6.5].

6.5.2

Application of seepage barriers
The preferential solution of many flood defense managers to allow the probabilityof piping to meet the failure probability is the fitting of seepage barriers. The total126required seepage length can be calculated using the models from section 6.1.3. It isthen up to the designer to determine where the seepage barriers can best beplaced. The following aspects can be taken into account:

To prevent leaching of sand particles at the site of construction transitions
often (short) seepage screens are used. These can of course be included in thedetermination of the total length of the seepage required.



Seepage must be sufficiently high, at least up to the design water level.

For works of art on a pile foundation where piping is excluded because thework of art is enclosed by an impermeable soil package, short seepage screensmust be installed. With this a possible opening between artwork and surface issealed. It is recommended that a minimum size of 2 meters be maintained forthe vertical length of such seepage barriers.



The following applies to seepage barriers that are placed next to the work ofart to prevent backward running (see figure 26):
from the deepest point below the work of art the depth per 3 m fromthe construction can be reduced by 1 meterthe screen must be at least 1 meter get stuck in the sand※（Rijkswaterstaat, Central government 2018）98 頁より作成。
Figure 26 Front view of seepage screens under a work of art at clay dyke99 頁
In principle, backwater running does not play a role in artworks in sand dikes;
in this situation, a test for microstability of the adjacent soil body must be
done. At the same time, the rear running screens must have been kept at a
certain minimum size outside the artwork; as a practical measure, take thelength of the seepage screen below the structure (see figure 27).

127

※（Rijkswaterstaat, Central government 2018）99 頁より作成。
Figure 27 Front view of sawn-screens underneath a work of art at sand dike
Finally, in the simple test rules (section 2.5 of [Reference 5.1]), a pipe with a pipe
diameter smaller than 0.50 m does not need to be evaluated. In the design of such apipeline a provision against piping must be included if the models in section 6.1.3
show that this is necessary.
6.6

Tightening necessary provisions against piping
Tightening of the required dimensions of seepage screens as determined with themodels in this chapter may possibly take place on the basis of:

Perform numerical groundwater flow calculations, taking into account, among
other things, the time dependence of the load.



Probabilistic piping or heave analysis.



Analysis of monitoring well measurements.

'Proven strength' analysis.

Handholds for this can be found in paragraph 8.3 of the Test Track Report piping
for works of art [Ref. 6.1]. It should be noted that the last two aspects can only be
used in the improvement of an existing artwork.
6.7

Other draft recommendations
When designing a work of art, there are a number of choices that can be made tosignificantly reduce the chance of failure or with which piping can be practically
excluded. A number of choices are mentioned below.
First of all, it is good to realize that designing the necessary provisions against
piping often does not have to take place at the cutting edge. Applying some
additional seepage length costs comparatively not much extra. This must be128weighed against the possible costs of further research.
It also applies that in a design situation uncertainties can often be eliminated bychoosing a solution where piping can be excluded on phenomenological grounds,
such as by applying filters.
Furthermore, it is recommended that direct monitoring wells be installed whenconstructing works of art. In this way, the operation of the seepage barriers can bemonitored over the lifetime and used calculation models can be calibrated for the
specific situation. (100 頁)Moreover, gathering data about the response of thehydraulic head in the water-bearing sand layers around the artwork on the outside
water level can provide more insight into the phenomenon of piping and eventuallylead to better calculation models.
6.8

ExampleIn chapter 11 of this Work Guide an example is included in which the required
dimensions of the seepage screens to prevent piping are determined. Furthermore,
integral examples are included in paragraph 12.3 of the Research Report on SandMealing Wells [Ref. 6.5] and in section 7.3 of Technical Report Sand-bearing
Wells [Ref. 6.10]. Various examples related to the determination of specific input
parameters for the Bligh, Sellmeijer, Lane and heave models can be found inchapter 7 of the Schematisation guide piping artwork [Ref. 6.3].

6.9

References and background documents[Ref. 6.1] Bree, B. van, WTI 2017 Key rules for works of art - Test report Piping,
Deltares, 1220087-003-GEO-0004, Version D2, December 2015
[Ref. 6.2] Guide to Design with Flood Opportunities - Safety Factors and Loads
for new Flood Risk Standards, version OI2014v4, Rijkswaterstaat
WVL, February 2017
[Ref. 6.3] WBI2017 - Schematisation guide piping artwork, Rijkswaterstaat
WVL, version final 1.0, January 2, 2017
[Ref. 6.4] Guidelines for Art Works 2003, TAW, May 2003
[Ref. 6.5] Förster U., Van den Ham G., Calle E., Kruse G., Research Report
Sand-Luring Welsh, Deltares, feature 1202123-003-GEO-0002, 2012
[Ref. 6.6] Jongejan R.B., Van Balen W., Calibration of semi-probabilistic test
prescriptions for under- and lagging, Deltares, reference 12006006129

006-ZWS-0002, 2012
[Ref. 6.7] Förster, U. et al., WTI2017 Schematisation guide piping at dikes,
Deltares, feature 1220084-006-GEO-0001 version 03, March 2016
[Ref. 6.8] Technical Report Soil Mechanic Schematising at Dikes, Expertise
Network Flood Defense, 2011
[Ref. 6.9] Lambert, J. (2015). Comparison methods determination timedependency head, Deltares note 1220088-003-VEB 0007-m[Ref. 6.10] Technical report Sand-bearing wells, Technical Advisory Committee
on Flood Defense, March 1999
[Ref. 6.11] Technical Report Water tensions at Dikes, Technical Advisory
Committee on Flood Defense, 2004
101 頁
[Ref. 6.12]

Hijma, M.P. and Lam, K.S., Global stochastic subsurface
schematisation (WTI-SOS) for the primary flood defense systems,
Deltares report 1209432-003-GEO-006, 2015130

103 頁

7

Structural failure

7.1

Introduction
This chapter deals with verifications for the failure mechanism constructive failureof flood defense structures in the design phase. The chapter serves as a support for
constructors who take care of the actual dimensioning of the construction. In orderto fully understand the Work Guide with regard to this failure mechanism,
knowledge of structural design, the probability of flooding and the applicablebuilding regulations (Building Decree) with the safety philosophy used in it isrequired.
Given the scope of the present Work Guide, the emphasis in this chapter is on theverification of the design with regard to the high water load. The flood tax isrelevant both for the Water Act and the Buildings Decree, with the Eurocodes
called by the Decree (NEN-EN 1990 to 1999). Since the Eurocodes pay little
attention to hydraulic constructions, this manual also focuses briefly on taxes
related to the other functions of hydraulic engineering works.

7.2

Scope and reading guideThis chapter describes the way in which the design of the structure must be
verified in accordance with the requirements of the Water Act and the Building
Decree for loads that the manufacturer considers relevant.
The first part of the chapter (sections 7.3 to 7.8) deals with the backgrounds of thestructural failure. The second part of the chapter (sections 7.9 to 7.12) is apractical description of the design verification. In most cases, certainly for theworks of art for which this Work Guide is written, the verification will be semiprobabilistic. The question when only a Building Decree or both a Building Decree
and Water Act Verification must be made is answered in section 7.8.1. A step-bystep plan has been provided in section 7.9 for both verifications. In short, thiselaboration comes down to the way in which reliability requirements have to betranslated into calculation values. The calculation value of the tax effect service
must always be smaller than the calculation value of the strength.
The way in which tax effects and the strengths of construction components are131

calculated is beyond the scope of this Work Guide. For this, reference is made toliterature on construction mechanics.
7.3

Phenomenological description structural failure
Structural failure can be caused by the failure of water-retaining construction
components and by instability of the structure and the adjoining ground body. The
failure tree is shown in Figure 28 below. This failure tree differs from the tree in
the WBI, which also has a branch for failure due to collision. Collision is consideredin this Work Guide for the design verification as part of event 2 (failure of waterretaining construction elements), see also section 7.10.6.2.

132

104 頁

Structural failure hydraulicstructureOr
Failure due to collapsing

Failure due to instability

water-resistantconstruction and groundconstruction components

body 1 and 4

And
Failure of water-retaining

Occurrence of flood

construction components due

effects

to hydraulic load 1 and 2

Or
Failure due to erosion

Exceeding coming power

during transhipment

3band/or overflow 3aAnd

Falling soil protection

behind hydraulic structure

Collapse hydraulicstructure due to erosion
subsoil※（Rijkswaterstaat, Central government 2018）104 頁より作成。
Figure 28 Failure tree failure mechanism structural failure
7.3.1 Failure as a result of failure of water-retaining construction components
Failure occurs when:(1) presenting a high waterAND(2) As a result, such large loads occur that the strength of the133

water retaining components more adequate and these arecollapsing. A large volume of water now flows in.
AND(3a) The soil protection behind the artwork collapses, after
which excavation pits in the (not protected) subsoil are created.
The artwork loses its stability with the result of a (progressive)
breach in the flood defense and substantial damage and/or
casualties (flooding) .26

OR(3b) The artwork maintains its stability and remains standing,but the inflowing volume due to the construction as a result of
the failure of the water retaining components (2) cannot berecovered in the underlying (water) system without this leading
to substantial damage. and/or victims (flooding).

___________________________________
26

In some cases, after the emergence of pit pits and loss of standing certainty, it may happen

that no progressive breach occurs, because, for example, the artwork is completely
embedded in hard quay constructions. In that case the situation corresponds to 3b. From theprimary function of the work of art, however, such an approach will not be desirable in thedesign. In the case of an assessment / assessment based on water safety, it can be used todemonstrate that the requirements are met.
____________________________________
105 頁
In most cases it is plausible that event 3a occurs instead of 3b, because there isoften a large decline over the artwork at the moment that construction components
collapse. The flow velocities that then occur after collapse are so great that the soil
protection usually cannot cope with them.
7.3.2

Failure due to instability of construction and ground body
Failure occurs if:(1) Presenting a high waterAND(4) As a result, there are such loads on the artwork and the adjacent
ground body that instability occurs in the form of vertical or horizontal
movement or tilting. This loss of stability leads to the occurrence of a(progressive) breach in the flood defense and substantial damage and/or
casualties (flooding)134

The difference with the partial failure mechanism as a result of failure of waterretaining construction components lies in the fact that failure due to instability
automatically causes the loss of stability of the total structure. This does not
require a failure of the soil protection. Exceeding the casing capacity is notconsidered here because the inflow volume is very large after total stability loss.
7.4 Failure and failure
The Foundations for Flood Protection [Ref. 7.2] states:
The exceeding of an ultimate limit state is also referred to as failure. Failure and failure are
not the same. With collapse, loss of coherence or large geometry change is indicated. A flood
defense can fail without collapsing. For example, the water can flow over the flood defense
and cause a flood, without the barrier collapsing. Conversely, a flood defense can collapse
without failing. For example, a superficial shearing of the inner slope of a dike does not haveto lead directly to flooding. Of course in that case a repair is necessary, because the flood
defense function is affected for the future.
From the perspective of the Water Act, failure is therefore equivalent to the occurrence of aflood. This means that failure encompasses all successive events that ultimately lead to aflood. For the structural failure mechanism, therefore, the chance of the top event from
Figure 28, a combination of different events, should be formally verified. In practice,
however, with most of the flood defense structures after the occurrence of an initial collapse
mechanism, event 2 or 4 in Figure 28, there will also be an overshooting of the storage
capacity or the collapse of the artwork after the failure of the soil protection. For this reason,
design is pragmatically recommended for initially looking at the initiation of failure, or event
2 or 4, instead of the top event.
In the Eurocodes reliability requirements have been set for the failure of a construction. In
the case of flood defense structures, this concerns events 2 or 4. (106 頁)All events after the
structural failure that may possibly lead to a flood are not included in the verification. Of
course the Building Decree does look at the consequences of collapse, but these are
discounted in the reliability requirements imposed on structural failure. The greater theconsequences of collapse, the stricter the reliability requirement for collapse. Rijkswaterstaat(Directorate-General for Public Works and Water Management) and other managers
generally set the highest reliability requirement for flood defense structures, namely therequirement associated with Consequence 3 (CC3) 27. This is motivated by the idea that135

flood consequences also occur in most circumstances after structural failure. When the costs
are highly dependent on the chosen consequence class and after failure no flooding is
expected or the probability of flooding from the Water Act is relatively smooth (e.g. + 1/100
per year), a lower class could also be chosen.
7.5

Limit position function collapse constructively
As discussed in the previous section, the Buildings Decree focuses on constructive
failure and, from the Water Act, it is also wise to look at constructive failure only
when designing.
The occurrence of structural failure can be described by a limit state function. Thisfunction indicates for each possible combination of loads and strength properties
whether the barrier will fail or not. A limit state function is often called a Z
function. This function has a negative value if the load is greater than the strengthand the barrier fails. In a limit state function all dimensions, variables andparameters occur that describe the strength of a structure (component) and theload on a structure (component).
A construction can fail due to multiple failure mechanisms. Thus, a structuralcomponent can collapse due to a shortage of shear force, moment or normal force
capacity in a particular cut. But chicken or kink instability or fatigue can also be a
problem. All these failure mechanisms have their own border state function.
The ultimate limit state is exceeded if the available strength of the structure islower than the load effects. This is expressed in the following generic limit statefunction:

In accordance with NEN-EN 1990:

Σ means "combination of"_____________________________________
27

In Dutch design practice, the English expression Consequence Class 3 (CC3) is also often

used. The English term is also used in this Work Guide.
136

28

In the literature, this generic limit state function often uses S instead of E. However, S

stands for load and E stands for load effect. With structural failure the load effect is used in
the limit state function, in accordance with NEN-EN1990. NB: in NEN-EN1990, F is usedinstead of S.
_____________________________________
107 頁
Here is:R

Strength of construction (part)

Xi

Material strength iθiModel uncertainty iaiGeometric data of construction (component) i

E

Tax effect

Fj

Tax j

θj

Model uncertainty jaj

Geometric data of construction (component) j

The total tax effect (E) is the result of (a combination of) considered taxes (Fi) in
combination with geometrical data of the construction and model uncertainties.
For the high water tax, this concerns the decay tax, wave tax and to a lesser extent
the own weight.
The total strength R with respect to the strength magnitude in question isdetermined by the relevant structural components with their material strengths (xi)and the strength models used in the structural mechanics with their uncertainties.
The limit state is exceeded when:

Either:In the Eurocode NEN-EN 1990 Foundations of the structural design, a distinction
is made between serviceability limit states and ultimate limit states. Constructive
collapse29 is a ultimate limit state, in which NEN-EN 1990 distinguishes between
:

30



STR: Internal collapse or excessive deformation of the structure or structural137

elements, including foundations on steel, piles, basement walls, etc., where thestrength of construction materials of the construction is decisive;

GEO: Settling or excessive deformation of the ground where the strengths ofsoil are decisive for the resistance to be delivered;

FAT: failure of the construction or structural elements due to fatigue.

For the high water tax, only the STR and GEO limit states are relevant from thepoint of view of the Water Act, which corresponds to the following assessment
traces in the WBI2017: Strength Construction components (STCO) and Stability
construction and ground structure (STCG). Other taxes to be considered can, ofcourse, concern STR, GEO and FAT limit states. For example, for a steel turningmeans of a construction in a tidal area, the FAT limit state should also be
considered. If this does not happen, fatigue may cause the actual strength to besmaller than assumed when assessing the water retaining capacity.
_____________________________________
29

NB: In the Eurocode, the term failure is used here, because in the Eurocode, failure =collapse
30

In addition, NEN-EN 1990 has the extreme limit state EQU: Loss of static equilibrium of

the structure, or of any part thereof, considered as a rigid body. This limit state is not a formof structural failure in the case of a water-retaining work of art burdened by high water.
_____________________________________
108 頁
7.6

Reliability of a construction
As explained in the previous section, a construction collapses if the strength of thestructure is less than the load on the structure. In most cases the strength and theloads are spread and not exactly known. This way the load varies over time. It istherefore impossible to design a structure that can never fail. For that reason, thereliability of a construction is examined. The reliability of a construction isexpressed as the probability of failure Pf or a reliability index (β), for a chosenreference period (tref). The reference period is the period to which the numericalvalue of the reliability relates, see for further explanation [Ref. 7.2].
The reliability of the artwork is expressed in a failure probability, or the chance of
exceeding the limit state:138

For the relationship between a failure probability and a reliability index:

At which:pf

Failure probability structural failure for a reference period equal to tref [-]βReliability index for a reference period equal to tref [-]Φ(...) Standard normal distribution

Following on from chapter 2 Design verifications on the basis of flood probability
standards, the development of the structural reliability over time is discussed
below, through developments of the strength and the loads over time. The focus
here is on the probability of failure in a year, given no failure in the previous years.
In other words, a reference period (tref) of 1 year.
The chance of failure in time is influenced by two factors;


The correlation between the failure events in the various years, in particular
because the uncertain strength parameters are constant over time (relegation
aside).

The course of the strength or load over time. For example: due to aging thestrength can decrease and due to climate change the load can increase.

In broad outline, four situations can be distinguished, shown in Figure 29:Figure 29 - top left describes the situation without correlation between the
failure events in the different years and with constant strength and taxes. In
this situation, the probability of failure in year i, given no failure in previous
years, will remain constant over time.

Figure 29 - bottom left also describes a situation without correlation between
the failure events in the different years, but with increasing load and / ordecreasing strength. In this situation, the probability of failure in year i, given
no failure in the previous years, will increase.

Figure 29 - right above describes the situation with strong correlation between
the failure events in the different years and with constant strength and taxes.
In this situation, the probability of failure in year i, given no failure in previous
years, will decrease over time. (109 頁)This phenomenon is also called "provenstrength".

Figure 29 - bottom right describes the most realistic situation with correlation139

between the failure events in the different years and an increasing load and /or decreasing strength. Firstly, the failure probability decreases over time by"proven strength", but then increases over time due to a decrease in thestrength and / or the increase of the loads (climate developments) over time.
This curve is also called the bathtub curve. The initial decrease in structural
collapse will only be large with a large proportion of the own weight of the load
and / or a very uncertain strength.

※（Rijkswaterstaat, Central government 2018）109 頁より作成。
Figure 29 The influence of time dependency and increasing taxes and / or strength
degradation on the probability of failure per year (N = 1) given no failure in previous years(Source: [Ref 7.2] and [Ref 7.4])
High-water art works generally have the failure probability as shown in the bottom
right-hand figure in Figure 29, the 'bathtub curve'. In the case of the bathtub curve,
the maximum annual failure probability is in the first or the last year of the140construction. In case of strong climate change (increase of the load in time) or
aging (decrease of strength in time) this will usually be the last year of life, as
shown in Figure 29. In case of a dominant permanent load (such as own weight ora relative great minimal decay) this will usually be the first year of life. In mostsituations, the probability of failure for high-wattage structures (which havesurvived the construction phase) is at most in the last year of life. (110 頁) Only in
exceptional cases is the chance of failure maximal in the first year of life.
7.7

Reliability requirements for the construction
To achieve a minimum degree of structural safety, reliability requirements are
imposed on a work of art:Or:

At which:
P eis

Failure chance work of art structural failure for a reference period equal toluck [-]

βeis

Failure probability expressed in confidence index for a reference period
equal to tref[-]

Both the Water Act and the Building Decree impose reliability requirements on
flood defense structures. The requirements of the Building Decree and the Water
Act differ on a number of points. Table 8 provides an overview of the mostimportant differences between the reliability requirements from the Water Act andthe Building Decree. Two differences are highlighted below:


The Building Decree is a constructive failure option for a construction and for
its individual construction components. The Water Act provides a floodprobability standard for a whole process. A requirement for the risk ofstructural failure for construction components can be derived from thisstandard. This difference has already been discussed in section 7.4.

The standards in the Water Act relate to a reference period of 1 year, which
implies that the artwork must meet the standards 31 derived from the standard
in every consecutive period of 1 year. The requirements according to the
Buildings Decree in NEN-EN 1990 relate to a reference period of 50 years. In
141the case of hydraulic engineering objects, a reference period of 100 years is
generally applied without adjustment of the reliability indices from NEN-EN
1990.
Table 8 Overview table Water Act versus Building Decree.
AspectReliability requirements

Reliability requirements

Water Act

Building Decree

Reliability requirements

Only works of art in primary

All water-retaining

apply toflood defense systems andstructures and all loadthen only (high) water

situations/combinations

defenseReliability requirement

Complete process

relates toDifferentiation

Construction component
and total construction

Flood probability standards

Three consequence classes,(maximum allowabledepending on theprobability of flooding)consequences. Per class 1

from 1/100 to 1 / 1,000,000

reliability requirement

per year(different for new
construction, rejection andrenovation)

Reference period

1 year> 1 year, for design 50-100
years※（Rijkswaterstaat, Central government 2018）110 頁より作成。
_____________________________
31

For the failure mechanisms: Overflow / transshipment, Do not close, piping andStructural failure_____________________________
111 頁
7.7.1

Reliability requirement Water Act
There are no specific reliability requirements in the Water Act for the structuraldesign of hydraulic structures with regard to (high) water defense. However, it isindicated which requirement a standard route must at least meet. From this route
requirement a reliability requirement for structural failure can be derived with areference period of 1 year, for more background see chapter 2 Design verifications
based on flood probability standards.
142

In short, it means that all parts of the artwork must be designed in such a way thatthey meet this derived reliability requirement in every year:

In which:
Peis, KW, CON

Failure probability for structural failure and no failure due tooverflow/transshipment of an individual work of art derived
from route requirement from the Water Act for a reference
period equal to luck = 1 year [-]Pmax

Failure probability for the entire dike section (standard route)based on the maximum permissible probability of flooding fromthe water law for a reference period equal to the tref = 1 year [-]ωCON

Failure probability factor for structural failure [-]cCorrection factor for the correlation between structural failureand failure through overflow/ transhipment [-]Ndsn

Length-effect factor for structural failure [-]In the standard failure probability distribution for a standard path, a value of 0.02
is used for the failure probability factor ωCON. This can be deviated from if it is not
obvious for structural failure (see also chapter 2 Design verifications based on floodprobability standards).
Correlation between structural failure and failure due to overflow/overtopping
The failure mechanisms structural failure and failure due to overflow/overtopping
are strongly correlated, because in both cases the hydraulic load is dominant for the
failure probability above the uncertainty of the strength and because the failure
probability for overflow/transshipment much greater than that for structural
failure. It is therefore likely that a construction has already failed as a result of
overflow/transhipment before structural failure occurs. In order not to dimension
the artwork unnecessarily conservatively, or to work with water levels far above thecrown, the degree of correlation between the two mechanisms is taken into accountby the factor c. (112 頁) In view of the required reliability, the calculation value ofthe outside water level can still be higher than the crown height according to thisWork Guide. However, excessive water levels high above the crown height are143

prevented by the factor c.
Table 9 Correction factor c for the correlation between structural failure and failure by
overflow/transshipment [Ref. 7.4]
Pmax [-]

1/100

1/300

1/1.000

1/3.000

1/10.000

1/30.000

c [-]

7

5

4

3

3

3

※（Rijkswaterstaat, Central government 2018）112 頁より作成。
Length effect
The length-effect factor Ndsn is formally determined by the number of more or lessindependent structural components in a range with the same reliability and thenumber of more or less independent instability mechanisms32 (STCG). In reality
there is a large degree of correlation due to the common load, namely the outside
water level. In addition, the construction components rarely have equal reliability
within a range:

There can be a big difference in construction period between artworks in one
process, which can lead to large differences in reliability between
constructions.

Material quality was less good in the past, building techniques and building
codes change over time and degeneration has occurred.



Major differences in reliability will generally also exist between main
construction components, because for example the high water load isdominant for the high-water-tight closing means and the own weight for thefoundation.



The same applies to the instability mechanisms, in general one mechanism isdominant.
Within the WBI2017, a fixed value of 3 is used for the length-effect factor Ndsn.
This estimate of Ndsn = 3 seems appropriate for most situations, which also
followed from an analysis of many VNK2 results. For designs, therefore, Ndsn =3 can be used.

7.7.2

Reliability requirement Building Decree
For the reliability requirements for new buildings, the Building Decree refers to
Eurocode NEN-EN 1990. In this, follow-up classes with corresponding reliability
requirements are determined. A reliability requirement is stricter if the144consequences of failure are more serious. In NEN-EN 1990 three consequenceclasses have been defined. The reliability requirements for the ultimate limit state
are shown in Table 10 for a reference period equal to the life span of the 50-year
construction. A lifespan of 100 years is often used for hydraulic engineering
constructions. As already explained in the beginning of section 7.7, these reliability
requirements can also be used for 100 years.
The reliability requirement in the Eurocode is in principle set to each construction
element separately and for each failure mechanism separately. The safety of thetotal construction as a system can therefore deviate from this. Usually the safety
will be higher, because normally a redistribution of the internal forces is possible assoon as the strength is exceeded locally.
___________________________
32

Horizontal or vertical instability and tilt instability___________________________(113 頁)The extent to which this is possible depends on the static system and on
the toughness properties of the materials and connecting elements used. Usually
the entire system meets the reliability requirement if the components meet33.
Consequence classConsequences of failure
Risk of life danger

CC3

Very bigCC2

Significantly

CC1

Excluded / small

Risk of economic damage
Or
And

Reliability
requirement for
longevity βeis, BB

Very big

4,3

Significantly

3,8

Excluded / small

3,3※（Rijkswaterstaat, Central government 2018）113 頁より作成。
Table 10 Reliability requirements NEN-EN 1990 as prescribed in Building Decree (BB)The relation between confidence index (β) and failure probability (Pf) is given informula 7.3.
For the reliability requirements for existing buildings, the Building Decree refers to
NEN 8700. However, this Work Guide only looks at new construction.
7.8

Design verifications constructive failure
In a design verification the reliability (failure probability) is confronted with thereliability requirement (failure probability). The reliability requirement follows
145

from the Building Decree or is derived from the Water Act. Chapter 7.6 discusses
the reliability over time and chapter 7.7 discusses the reliability requirements.
7.8.1

When a Building Decree and Water Act Verification?
The (provisional) design of a water-retaining artwork must always be verified withregard to structural failure based on a reliability requirement from the Buildings
Decree (7.7.2). In addition, it may be that the (preliminary) design must also beverified on the basis of the reliability requirement for structural failure from theWater Act (7.7.1). The Water Act Verification is only required in the event of
failure of the construction or the structural component, as a result of theconsidered load situation, a flooding will occur. Below are some examples which
are not exhaustive. The manufacturer must determine for himself which
verifications are necessary for the combination of the construction (part) and theload situation.
For example 1:Construction component: lock gate in the outer head of a lock.



Load situation: the high water load situation.



Result in failure: flood.
Failure of the outer door leads to the loss of water retaining capacity as it isplausible that the strength of the inner door is less than or equal to the outer
door and will also collapse. Failure event 3a or 3b (section 7.3.1) then occurs.



Design verifications: Building Decree and Water Act

114 頁
For example 2:Construction component: lock door in the outside of a lock.



Load situation: hanging door after renovation work by means of a floating
buck.



Result in failure: only damage to the door. The probability of a flood is small
because it is not suspended in the high water season and only in calm
weather conditions. In addition, there is relatively much time for emergency
measures, should higher water levels be expected anyway. As a result, thewater retaining capacity is not jeopardized.

Design verifications: Building Decree

For example 3:146

Construction component: wing wall on the inland side of a lock.



Load situation: the high water load situation.



Result in failure: local damage artwork. The collapse will not lead to loss ofwater retaining capacity of the lock.



Design verifications: Building Decree.

For example 4:Construction component: foundation outer head of the lock.



Load situation: the high water load situation.



Result in failure: flood. Instability of the foundation will lead to the loss ofwater retaining power, after which a (progressive) breach will arise (failure
event 4 in section 7.3.2).



Design verifications: Building Decree and Water Act

Restrictions regarding the Water Act verification
Unfortunately, at this moment only the semi-probabilistic design verification withrespect to the reliability requirement from the Water Act for the flood water
situation is facilitated with calculation rules. The step-by-step plan for going
through this verification is included in section 7.9.
However, there are also other loads that cause a significant flood risk in the eventof structural component failure. For example, shipping taxes on reversing means
where, in case of failure, a large volume of water flows into daily situations. The
design must then also comply with the reliability requirement from the Water Act
in respect of these loads. However, semi-probabilistic calculation rules based on
the Water Act are currently lacking to do this. In line with current design practice,
it is sufficient to carry out a semi-probabilistic verification according to the
Buildings Decree with the highest reliability requirement (CC3) andcorresponding partial safety factors. When the design then meets, the Water Act
will practically certainly also be complied with. Explanation of the semi-biblicalverification follows in section 7.8.4.2.
Probabilistic verification is always possible, even though it is currently not
facilitated. Explanation of the probabilistic verification follows in section 7.8.4.1.
115 頁
7.8.2

Design verification according to the Building Decree147

The construction (component) must meet the reliability requirement or failure
probability in the Buildings Decree during the planned service life (see paragraph7.7.2). The failure probability of the construction (with a lifespan of 100 years) in acontinuous period of 100 years to meet the failure probability that has been set for
100 years, see Figure 30.
As discussed in paragraph 7.6, the failure probability of a work of art depends on
the tax considered, its development over time and the development of strength
over time. In the failure probability analysis of flood defense structures burdenedby high water, the probability of failure is generally the greatest in the last year of
life. This is the failure probability trend as outlined in Figure 30: the 'bathtub
curve'.

※（Rijkswaterstaat, Central government 2018）115 頁より作成。
Figure 30 Verification of failure probability from the Building Decree. The area under the
curve is equal to the failure probability. Note: failure probability is specifically associatedwith (high) water catchment
In accordance with current design practice, the design verification will often be
semiprobabilistic. This approach is explained in the following sections:

Section 7.8.4.2 discusses the nature of the semi-probabilistic verification
procedure.
148



Section 7.9.1 provides the step-by-step plan for completing the semiprobabilistic verification for the flood water situation.

Section 7.9.2 provides the step-by-step plan for completing the semiprobabilistic verification for other loads, such as wind load or tensile forces ect.

7.8.3

Design verification according to the Water Act
A construction (component) must comply with the failure probability derived fromthe maximum permissible probability of flooding from the Water Act in each yearof the planned lifespan (see section 7.7.1). Calculation rules for semiprobabilistic
verifications based on the Water Act are only available for the flood water situation.
For the other tax situations that collapse and cause a flood, no semi-probabilistic
calculation rules are available from the Water Act and reference is made to section
7.8.1.
As mentioned, the risk of failure is generally greatest in the last year of life forwater-retaining structures subject to flooding. In that case the design in the lastyear of life must be compared with the failure probability from the Water Act, see
Figure 31.（116 頁）※（Rijkswaterstaat, Central government 2018）116 頁より作成。
Figure 31 Probability failure check from the Water Act, where the realized probability of
failure in the last year of life is normative149

In rare cases, the probability of failure will be greatest in the first year of life. Thisis the case if the own weight load is dominant over the hydraulic load during a highwater situation. In that case, the probability of failure in the first year of life should
be compared with the failure probability for the Water Act, see Figure 32.

※（Rijkswaterstaat, Central government 2018）116 頁より作成。
Figure 32 Verification of failure probability from the Water Act, where the realized
probability of failure in the first year of life is normative
Again, in accordance with current design practice, the design verification willusually be semi-biblical, with section 7.9.1 providing the step-by-step plan forcompleting the semi-biblical verification for the high water load situation.
117 頁
7.8.4

Types of verification procedure
A probabilistic or semiprobabilistic design verification can be carried out on thebasis of the limit state function discussed in the previous paragraphs and thereliability requirements for a construction. This verifies whether the design meetsthe reliability requirements from sections 7.6 and 7.7.

7.8.4.1. Probabilistic verification
This verification method is interesting when very sharply designed, because of(very) high construction or renovation costs.
150

In a probabilistic verification, the (ultimate) limit state function is fed withprobability distributions of strength and loads. The probability distributions of thewater level and the significant wave height can be found for every location with
Hydra-NL. For the probability distributions of possible other loads, theconstruction properties and the model uncertainties, it is recommended to use theJCSS Probabilistic Model Code(http://www.jcss.byg.dtu.dk/Publications/Probabilistic_Model_Code); where
relevant, the distributions must be brought into line with the prevailingcharacteristic values according to the Eurocode.
In case of probabilistic verification, the reliability of the structure is expressed as a
failure probability Pf and the following condition is met:

In which:
Pf

Failure probability structural failure for a reference period equal to tref [-]Peis

Failure probability work of art structural failure for a reference period
equal to luck [-]In the case of the Water Act, this concerns an annual verification and, in the case of
a Eurocode requirement, a verification for a reference period equal to the life span.
7.8.4.2. Semi-probabilistic verification
In a semi-probabilistic verification, the limit state function is not fed withprobability distributions but with calculation values. A calculation value is usually a
combination of a representative value and a partial safety factor (see chapter 2
Design verifications on the basis of flood probability standards). A partial safety
factor is calibrated so probabilistic that, when used in the Netherlands, theapplicable reliability requirements for unity check (UC) are lower than 1, or UC <1(Building Decree and/or Water Act). The unity check is defined as follows:

At which:Ed

Calculation value tax effect
151

Rd

Calculation value strength construction(118 頁)A

construction meets the reliability requirement when:

Either:1) Calculation value strength
The calculation value for the strength Rd follows from formulas 6.6a to 6.6c in
NEN-EN 1990.
2) Calculation value tax effect
For FAT border states (fatigue) NEN-EN 1990 refers to NENEN 1992 and NENEN 1999.
For STR and GEO boundary states, a distinction is made in NEN EN 1990
between:- Permanent and temporary taxes: By far the most taxes or combinations of taxes
fall under this category, such as the flood tax. The calculation value for the tax
effect (Ed) follows from formula 6.10a (Ed, a) and formula 6.10b (Ed, b) in NENEN
1990, where:- Extraordinary taxes: The calculation value for the tax effect (Ed) follows fromformula 6.11a from NEN-EN 1990.
The flood tax falls under permanent or temporary taxes. Section 7.10.2 specificallyaddresses design verification in this respect. For the other taxes to be considered,the designer himself has to determine in which category they fall.
7.9

Step-by-step design verification
The step-by-step plan is included in the figure 33 below. The starting point of thestep-by-step plan is a preliminary design of the flood defense artwork. The spatialintegration and the design have already been determined, partly on the basis ofother functions. In addition, provisional dimensions and material types have been152

assigned to construction components on the basis of functional considerations orrules of thumb. The following step-by-step plan outlines how, step by step, it canbe verified semi-probabilistically whether the construction components are
sufficiently strong and stable to meet the reliability requirements from Water Act
and Building Decree. Another order can be followed as long as all steps are taken.
Of course, there can also be probabilistic verification, but only in limited cases willthat have added value. That is why the step-by-step plan for probabilistic
verification is included in Appendix E.
Below is a brief explanation of the steps indicated:
Step 1. In this step the construction component or the combination of
construction components is chosen which must be verified against thereliability requirements. (119 頁)All construction components must
eventually be verified.
Step 2. For the structural component selected in step 1 or the chosen
combination of components, it must be checked which loads areimportant. For example, a foundation pile will not be loaded by a screw
radius load and a wooden point door will not be subject to a road trafficload. See section 7.10 for all possible loads.

153

Step 1:
Choose a construction component in the (preliminary) design
which must be verified against the structural reliability
requirement (s)Step 2:
Determine all relevant loads that can or will load the structuralcomponent in the lifetime.

A. Design verification procedure for situationsof failure and flood consequences

Comply with Building Decree and Water
Requirements

A1. Design verification procedure for the

B. Design verification procedure for situationsof failure without flood consequences
Complying with Building DecreeA1. Design verification procedure for theother situations (not worked out)high water load situation※（Rijkswaterstaat, Central government 2018）119 頁より作成。
Figure 33 Roadmap for design failure mechanism structural failure
Continuation explanation on step-by-step plan:
A or BA distinction is made between the verification procedure for situations
where, in addition to collapse, there is also a flood (A) and for othersituations where only collapse occurs (B). In case of (A), the reliability
requirements from both the Water Act and the Building Decree must be
considered. In all other situations (B), only the reliability requirementsfrom the Buildings Decree need be considered.

A1 or A2 As indicated in section 7.8.1, only semi-probabilistic calculation rules areavailable for the high water load situation for the situations where failure
and a flood occur (A). The verification for this has been elaborated in
sub-step plan A1 (see Figure 34). For the other situations (A2) wherecollapse and flooding occur, semi-probabilistic calculation rules based on
the Water Act are currently lacking. In line with current design practice, it154

is recommended that semi-probabilistic verification according to the
Buildings Decree with the highest reliability requirement (CC3) andcorresponding partial safety factors should be carried out according toprocedure B. If the design then complies with the Water Act willpractically certainly also be complied with.
Verification procedures A1 and B are further elaborated in Figure 34 and Figure
35, respectively.

155

120 頁
A1. Design verification procedure for the high water load situation
Comply with Building Decree and Water Requirements
Step 3: Determine the reliability requirement from the Building
Decree: βeis, BB

Step 4: Determine reliability requirement from Water Act: Peis,KW,CON
Step 5: Collect the data of the construction component in the

Customize design slide lesson(preliminary) design, needed for the strength calculation.

Step 6: select the strength to be verified and determine thecorresponding limit state function / unity check.

Step 7: Calculate the representative strength of the structural component(Rrep) based on its (preliminary) design dimensions and material strength
according to the Building Decree (NEN-EN 1992-1999).

Step 8: Determine the calculation value of the strength (Rd) according to
NEN-EN 1992-1999.

Step 9: Generate the marginal water level, wave height and wave period statistics
with Hydra-NL. Determine the correlation between water level and waves.
Step 10: Determine the calculation value of the load effect (Ed, BB) on
reliability requirement from the Buildings Decree.

Does not suffice

Step 11: Verification Building Decree by means of Unity check:No

Yes
Step 12: Water law verification required only for: failure and flooding

consequences. Determine calculation value of the load effect (Ed, ww) on
reliability requirement from the Water Act.

Step 13: Verification Water Act through Unity check:

Yes

Satisfies※（Rijkswaterstaat, Central government 2018）120 頁より作成。
156

Figure 34 Step-by-step design verification A1 for high water load situation
121 頁
7.9.1

Design verification procedure for the flood water situation (A1)
Step 3. The reliability requirement from the Buildings Decree depends on therequired Consequence Class, see paragraph 7.7.2.
Step 4. The reliability requirement for structural failure from the Water Act isderived from the flood probability associated with the standard route inwhich the work of art is constructed, see paragraph 7.7.1.
Step 5. For information, see the (preliminary) design. The design verification of
the structural component, or combination of components, with regard to
the load situation (high) water defense involves checking whether thestrength is sufficient to withstand the load. To this end, strength
calculations need to be made, for which information about the dimensions
and type of material is required.
Step 6. See section 7.5. The structural component or the combination ofcomponents can collapse in many ways, for example due to a shortage ofmoment capacity or due to too little resistance to buckling. The limit statefunction can also be expressed as a unity check (UC). In some cases the
UC is already prescribed in the Eurocodes and the limit state function nolonger has to be determined (see paragraph 11.6 of Chapter 11 Case).
Strength: To be determined with the help of the rules of constructionmechanics or with a specialist FEM calculation. This falls outside thescope of the Work Guide.
Load: The load on the construction has a load effect on the structure.

In the case of (high) water defense, the load consists of decay, waves
and own weight load, see section 7.10.2 for the tax effect.
ExampleThe chosen structural component concerns a purlin in a door, which
can be schematized as a beam on two supports with a distributed load
q. It must be verified whether the chosen IPE profile is sufficient towithstand the current moment due to hydraulic load.
The hydraulic load results in a distributed line load q on the purlinThe maximum field moment

The strength of the purlin expressed in moment capacity157



Border status function:

Equivalent expression:Construction component satisfies as: Z≥ 0

Expressed in UC for semi-probabilistic verification: UC=

122 頁
Step 7. Using the mathematical relation for the strength from step 6, the type ofmaterial and the provisional dimensions of the construction part fromstep 5, the manufacturer determines the representative value by means of
NEN-EN 1992 to 1999 (choice depending on the type of material).
strength Rrep of the considered strength of strength, such as the moment
capacity or the shear capacity.
ExampleIn this case, Rrep is expressed in- σrep = representative bending strength (NEN-EN 1992 up to andincluding 1999)- W = resistance moment of the construction part
Step 8. With the help of NEN-EN 1992 to 1999 (choice depending on the type ofmaterial), the constructor determines the material factor Ym and thus thestrength Rd.
ExampleIn this case Rd is expressed in
It should be noted that the material factors and formulas with calculation
values for the strength (resistance) in NEN-EN 1992 up to and including
158

1999 are derived for CC2. The factors do not have to be adjusted, as in
the past, when performing a Water Act verification. In determining the
calculation value of the load (Ed) with the standard method (section
7.10.2) this has already been taken into account.
Step 9. The hydraulic load is location-specific. At this moment it is not yet
possible to determine the local statistics of the hydraulic load with load
models. For this reason, the manufacturer will have to determine thehydraulic load himself on the basis of the outside and inland water level,
the wave height and the wave period. The marginal statistics can be
determined with Hydra-NL, see also chapter 2 Hydraulic loads. In order
to combine these statistics with the statistics of the hydraulic load on the
structure, the mutual correlation must be known, see section 7.10.2.1 foran explanation.
Building decision verification:
Step 10. The tax effect Ed, BB is determined by means of formulas 6.10a and 6.10b
and the reliability requirement from the Buildings Decree, see paragraph7.10.2. Summary: with regard to the high water load situation, the effectof 6.10a is included in Appendix C and 6.10b in Section 7.10.2 (the'standard method').
ExampleIn this case Ed is expressed in
Step 11. The actual verification concerns the unity check: the construction
component or combination of components is sufficient when UC <1.0.


If UC <1.0: continue with step 12 and / or check whether the design
is fine.

123 頁
If UC> 1.0: continue with step 5, adjusting the dimensions andperhaps even the material type. The subsequent steps must then befollowed again. One can also choose to proceed first with step 12 andcomplete the Water Act Verification. It may be that according to theWater Act the component is even more disapproved.

159

ExampleIn this case:
Water law verification:
Step 12. The tax effect Ed, WW is determined by means of formulas 6.10a and 6.10b
and the reliability requirement from the Water Act, see paragraph 7.10.2.
Summary: with regard to the high water load situation, the effect of 6.10a
is included in Appendix C and of 6.10b in Figure 36 (the 'standard
method').
ExampleSame as Building Decree verification.
Step 13. The actual verification concerns the unity check:

If UC <1.0:

The construction component complies with the relevant strengthvariable. Continue with step 6 where all other relevant strengthvariables are verified. In addition to, for example, the moment
capacity of a beam, the shear force and possibly also the stabilityof the profile should also be verified.



If the structural component satisfies all relevant strengthvariables, a subsequent component can be selected and we startagain in step 1.



If UC> 1,0: continue with step 5, adjusting the dimensions andperhaps even the material type. Subsequently, the successive steps
must be followed again.

7.9.2

Design verification procedure for other load situations (B)The design verification procedure for 'other taxes' is without Water Act
verification. As discussed under option A or B, it is recommended to choose thereliability requirement for CC3 in the event that the relevant load still causes a
significant flood risk. The following description of procedure B is limited to thedifferences with the procedure for the high water load:
Step 4/12/13: N / A.
Step 9. No tax statistics need to be generated in procedure B. The representativevalue of the tax can be obtained directly from the Eurocodes NEN-EN
1992-1999 for general taxes and for typical loads on hydraulic structures160

from Table 11.
Step 10. The calculation value of loads can be determined with the baling factors
from NEN-EN1990 / 1991 and the representative values from step 9.
Where for loads typical of hydraulic constructions use can be made ofTable 11.

161

124 頁
B. Design verification procedure for situations of failure without
flooding consequences

Complying with Building Decree
Step 3: Determine the reliability requirement from the Building
Decree: βeis, BB

Step 4: Determine reliability requirement from Water Act: Peis,KW,CON
Step 5: Collect the data of the construction component in the(preliminary) design, needed for the strength calculation.

Step 6: select the strength to be verified and determine theCustomize design slide lesson

corresponding limit state function / unity check.

Step 7: Calculate the representative strength of the structural component(Rrep) based on its (preliminary) design dimensions and material strength
according to the Building Decree (NEN-EN 1992-1999).

Step 8: Determine the calculation value of the strength (Rd) according
to NEN-EN 1992-1999.

Step 9: (deviating from step 9 at high water situation)
Determine the represenative values of the occurring taxes (s rep) in accordance with the

Building Decree (NEN-EN 1990 and 1991) and in the case of typical hydraulic engineeringloads; Table 3.

Step 10:(deviating from step 10 at high water situation)
Determine the calculation value of the tax effect (Ed, BB) in accordance with
the Building Decree (NEN-EN1990) and Table 3.

Step 11: Verification Building Decree by means of Unity check:

Does not suffice

No

Yes

Step 12: Water law verification required only for: failure and flooding
consequences. Determine calculation value of the load effect (Ed, ww)
on reliability requirement from the Water Act.

Step 13: Verification Water Act through Unity check:

Satisfies※（Rijkswaterstaat, Central government 2018）124 頁より作成。
162

Figure 35: Step-by-step plan for design verification B. other taxes
125 頁
7.10

Taxes
When determining the load effect, all combinations of loads that may occur during
the construction phase, use and maintenance must be taken into consideration.
Where relevant, account should be taken of the dynamic nature of taxes and thetaxes associated with the situation of "not (timely) closing of weathering".
In accordance with the Eurocode NEN-EN 1990, a distinction can be madebetween permanent, variable and special taxes. The following paragraphs will
discuss the calculation of the calculation values of these loads in more detail. In
addition, we also consider (special) usage taxes.

7.10.1

Calculation values for the load
Calculation values of loads are given in NEN-EN 1991. However, hardly any
mention is made of hydraulic constructions, hence the calculation values of themost important loads on flood defense structures are included in Table 11. The
designer himself must comply with Step 2 of the step-by-step plan in Section 7.9.
determine the relevant combinations of taxes,
using Table 11 below and the loads described in NENEN 1991. Some taxes exclude
each other, so that they do not have to be considered in combination with eachother.

Table 11: Calculation values of loads typical for flood defense structures
Tax

Calculation value as

Calculation value as adominant load (belonging to

combination tax

CC2 from NEN-EN1990)
PERMANENT:
Own weight(1.35 or 1.0 or 0.9) Frep andIn accordance with NEN-

paragraph 7.10.2

EN1990 / NB

Ground pressure

1.0 Frep

Groundwater pressure

See section 7.10.4.3

Setting(1,2 or 1,0 or 0,9) urep

VARIABLE:
Pressure differences (high)163

water retaining.
- water levels

See section 7.10.2

See section 7.10.2- wind waves

See section 7.10.2

See section 7.10.2- water levels

See section 7.10.3

See section 7.10.3- wind waves

See section 7.10.3

See section 7.10.3

Flow

1,3 F50

1,3 F1

Ship waves

1,3 Frep

1,3 Frep

Ship flow

1,3 Frep

1.3 Frep

TrootsSee section 7.10.5.4

See section 7.10.5.4

Wind load

1,5 Frep

1.5 Ψ Frep (Ψ = 0.2)

Temperature

1,5 Frep

1.5 Fmomentaan

Traffic tax

1,35 Frep

1.35 Frep

Collision

Fd (see section 7.10.6.2)

0Earthquake

Customization: see last

Customization: see last state

position of knowledgeof knowledge

Explosion

Fnominaal0

Ice

FCUR166

0Flow (do not close)

Fd (see section 7.10.6.1)

0

Vandalism / sabotage--

Pressure differences otherwater retaining
situations related to:

SPECIAL:

Frep = Representative value of the load according to the building regulations
Fn = Representative value of the tax for variable loads with a repetition time of one year
Fnominaal = Nominal value of the special tax
Adjust calculation value for CC1 and CC3:
The above factors for permanent and variable loads apply to CC2. For CC1 and CC3, thepermanent and variable load factors are multiplied by 0.9 and 1.1 respectively. This does
not apply to loads of water levels and wind waves; for these taxes reference is also made toparagraph 7.10.2 for the differentiation.
※（Rijkswaterstaat, Central government 2018）125 頁より作成。
126 頁
In addition to the aforementioned 'external' taxes, in the case of flood defense
structures, 'internal' taxes associated with the use of the artwork must be taken into
164

account. Consideration can be given to the forces on reversing means from theguide through the deformation of bearings, the forces from the movement work on
the reversing means if the movement is blocked at the bottom by an obstacle, orthe holding force from the movement work. This guide does not provide any
further information about this, but it must of course be taken into account.
Damage by internal forces can ultimately also have consequences for theavailability of the artwork and thus for safety.
7.10.2High water load situation
This section considers the high water load situation, which is a combination of thehydraulic load at high water and the own weight load. The hydraulic load consistsof the decay load and the wave load [Ref. 7.3]. Other taxes will generally not be
relevant for this tax situation. Also the wind load is not, because in the high waterload situation in particular construction components are loaded that turn water.
The water in that case is so high that the extra load by wind does not matter or isnil. Other hydraulic load situations, such as in the case of a negative return of wateror the drying situation, are discussed in section 7.10.3.
Due to the lack of suitable load models for the time being, the decay and wave
loads in the calibration of the semi-probabilistic method are combined in thehydraulic load term (S), where for S a Gum distribution is assumed [Ref. 7.3]. In
reality, S is a function of the decay (V) and the wave load (H):127 頁
As stated in section 7.8.4.2, the calculation value of the tax effect Ed is determinedby the maximum of Ed, a and Ed, b (formulas 6.10a and 6.10b from the NEN-EN
1990). When formulas 6.10a and 6.10b are completed for the high water load
situation, only the hydraulic and self weight load is therefore relevant and follows:
Own weight dominant:Hydraulic load dominant:
At which:Ed, aCalculation of the tax effect when the own weight is dominantEd, bCalculation value of the load effect when the hydraulic load is dominant

Gk

Characteristic value own weight tax
165

KFI

Factor that in the case of the assessment in accordance with the Building
Decree depends on the chosen consequence class CC1, CC2 or CC3 andin case of verification in accordance with the Water Act is set equal to 1.0

YG

Partial factor for permanent loads

ξ

Reduction factor for unfavorable own weight tax

Sd

Calculation value of the hydraulic load at high waterΨ0

Tax combination factor

In the vast majority of cases 6.10b will be decisive for the high water load situation.
Only in case the own weight covers 80% or more of the total load, can 6.10a givethe normative tax effect.
For the own weight load, a load factor (YG) must be combined with thecharacteristic value of the own weight (Gk). For the hydraulic load, expressed aswater pressure on the structure, it was decided not to apply a partial factor, but toprescribe the exceedance probability of the calculation value of the load P (S> Sd).
With this exceedance probability and the tax statistic, the calculation value of Sd
can then be determined directly. The prescribed exceedance probability P (S> Sd)
is derived from the constructive reliability requirements from the Water Act(section 7.10.2.5) and the Building Decree (section 7.10.2.4) [Ref. 7.3]. The
advantage of this method over the old method with a load factor is that the pressure
figure with which it is calculated remains physically correct. The exceedances forthe hydraulic load and the load factor for the own weight load have been calibrated
with regard to model uncertainties.
In order to be able to determine the calculation value of the hydraulic load, thestatistics of the hydraulic load S are required. This is determined by the difference
between the load from the outside water (outside water level and waves) and theload from the inland waterway. In the following, the inner water level is assumed tobe constant for the sake of convenience. In section 7.10.2.3, the calculation value ofthe inland water level is discussed in more detail.
Ideally, the available instruments are suitable for determining the calculation valueof the load from the outside water, which is a function of the combined statistics ofoutside and inland water level, wave height and wave period. (128 頁)At thismoment the instruments (such as Hydra-NL) are not yet suitable for this. With
166

these instruments, only the marginal statistics of the outside water level, thesignificant wave height and wave period can be determined (in the form of
exceedance frequency lines) 34. In addition, local waterways are selected for inland
waterways, how to deal with them is described in section 7.10.2.3.
In order to be able to determine the calculation value of the hydraulic load Sd, usemust be made of calculation values of decay V and wave load H. The calculation
values of these variables are defined on the basis of their exceedance probabilities P(V> Vd) and P (H> Hd) .
When determining the calculation values Vd and Hd, a number of matters areimportant:1.

Own weight load dominant: If the constructor estimates that the own weight is
80% or more of the total load, then the design must be verified with Ed
according to 6.10a and 6.10b. Since the hydraulic load is not always thedominant load, Sd has a relatively high exceedance probability (low returntime). This also applies to Vd and / or Hd. Because these are exceptionalsituations for high-flood works, this verification is not explained in the main
text but in Appendix C.

2.

Hydraulic load dominant: For high-water works, 6.10b will almost always givethe normative load effect, see also [Ref. 7.4]. Then one can suffice with just averification according to 6.10b. If the hydraulic load is dominant, Sd has arelatively small exceedance probability (large return time). This also applies to
Vd and / or Hd. This results in the 'standard method' shown schematically in
Figure 36.

3.

Fault or wave load dominant within the hydraulic load: In both 6.10a and6.10b the decay or wave load (Vd or Hd) within the hydraulic load Sd can be
dominant. In advance it is not always possible to determine which is dominant,both tax combinations should be considered.

4.

Correlation between outside water level and significant wave height:
If the outside water level and the significant wave height are perfectly
positively correlated, then P (S> Sd) = P (V> Vd) = P (H> Hd). In all othercases, it is conservative to determine both Vd and Hd with an exceedance167

probability equal to P (S> Sd). In order to prevent excessive conservatism,combination values can then be used. There are two possibilities: Vd isdominant or Hd is dominant. The dominant tax variable always has thesmallest exceedance probability. See also section 7.10.2.1.
________________________________
34

NB1: with Hydra-NL the joint statistics of outside water level and waves are used todetermine the HBN (required crown height). See chapter 3 Hydraulic preconditions. NB2:
At the time of writing (July 2018), the WBI is exploring the options for directly determining
the calculated value of the hydraulic load Sd associated with a prescribed chance of
exceedance with Riskeer for the sight years up to and including ca. This application will not
be available until mid-2019 at the earliest.
_______________________________
129 頁
V and H are strongly correlated:
P(V>Vd) = P(S>Sd)=Pdb
P(H>Hd)=P(S>Sd)=Pdb

Vd dominant

V and H are weakly correlated:
P(V>Vd) = P(S>Sd)=Pdb
P(H>Hd)=Φ(Φ-1(Pdb)・0,4)=Pndb

Hydraulic load dominant: 6.10b
Ed,b=KFI・YG・ξ・GK＋Sd

V and H are strongly correlated:See e.

Hd dominant
V and H are weakly correlated:
P(V>Vd) = Φ(Φ-1(Pdb)・0,4)=Pndb
P(H>Hd)=P(S>Sd)=Pdb※（Rijkswaterstaat, Central government 2018）129 頁より作成。
Figure 36: 'Standard method' determine exceedance probabilities calculation values fordecay and wave load according to 6.10b.


Pdb = exceedance probability in case of dominant load

Pndb = exceedance probability in case of non-dominant loadQuantification Pdb and Pndb according to Building Decree and Water Act: seesections 7.10.2.4 and 7.10.2.5.
168

As stated in section 1.3 in general for the Work Guide, the method discussed here
for determining the calculation values of the hydraulic and self-weight load is notreadily suitable for longitudinal structures.
7.10.2.1. Correlation between decay and wave tax
In the diagram in Figure 36 an estimate must be made of the correlation between
the decay load and the wave load. In the case of a strong positive correlation
between outside water level and waves, there is a high probability that a large wave
height and period will occur when a high water level occurs. Depending on theorientation of the artwork, this may be the case along the coast where both thewater level and the waves of wind are dominated. When the orientation
approximately corresponds to the dominant wind direction, decay and wave loads
will be strongly correlated. If the orientation of the artwork deviates a great deal
from the dominant wind direction, which determines the water level along thecoast, then the decay and wave loads on the artwork are not or hardly correlated.
In the case of a weak correlation between water level and waves, the occurrence ofa certain water level says little about the wave height and period. This is the case,for example, in the upper river area where the water level is heavily discharged
while the waves are determined by local wind. In this situation, the orientation of
the artwork no longer matters for the correlation between the decay and wave load.
Of course, the correlation between water level and waves can also be between
strong and weak. At this moment it is not possible to make a statement about thecorrelation with Hydra-NL. Hence, it is recommended to assume full correlation,
except for the above-mentioned exception of the upper river area.
When wave heights are small compared to the outside water level, the degree ofconservatism is small in this assumption. But when it is expected that this is
unnecessarily conservative in this way, advice can be requested through theHelpdesk Water.
130 頁
7.10.2.2. Calculation value of wave tax
Wave loading is caused by wind. The wave load varies over the height of theartwork. The wave load can be calculated with several models and depends, among169

other things, on the wave height, wave period and angle of incidence. In WBI2017
the wave load model of Goda is implemented, the most used model at the moment
to determine wave loads on a vertical wall. The model, to be used for the semiprobabilistic application, is included in Appendix D.
To determine the calculation value of the wave load Hd, use must be made of a load
model (for example, model of Goda), the exceedance probability of the calculation
value P (H> Hd) (see Figure 36 and paragraphs 7.10.2.4 and 7.10.2.5) and the
combined statistic of water levels and wave characteristics.
The probability distribution of the wave load on a work of art on the location of abank location cannot currently be determined with the current instruments. As
already indicated in section 7.10.2, the marginal statistics on the water level andthe wave characteristics (Hydra-NL) are forced to work. The marginal statistics forthe significant wave height (Hs) and wave period (Tm-1.0) are omni-directional.
This means that no account has been taken of a specific direction of wave
incidence.
There is a dependency between the wave height and the wave period. It is
recommended to assume full correlation between the wave height and the wave
period. This means that the calculation values of these variables must be
determined with the same exceedance probability. A precondition here is that thiscorrelation does not lead to unrealistic wave losses. Thereby it can be assumed(conservatively) that the resulting wave load is associated with waves that areperpendicular to the structure.
The method for determining the calculation value of the wave load Hd falls apart in
the following steps:
1. Determine the calculation value of Hs by means of its marginal statistics and, see Figure 36 and Table 12 and Table 13:
2. Determine the calculation value of Tm-1.0, by means of its marginal statistics and3. Assume a frontal wave attack
4. Calculate the calculation value of the wave load Hd using a wave load model, forexample the model of Goda (Appendix D). This load is expressed in terms of a170

pressure gradient across the height of the structure.
With this method the upper limit of the calculation value of the wave load isdetermined. A calculation with a probabilistic wave load model always yields alower calculation value.
An important fact is that in many cases the wave load is relatively small comparedto the expiry tax. In the river area the waves are usually small because the length of
the wire is often short and where large waves are to be expected, often breakwaters
are used. When it is therefore expected that the above method is unnecessarily
conservative, the advice of the Helpdesk Water can be requested. (131 頁)Finally, it
should be noted that no reduced reliability index applies to wind waves, such as
wind pressures in the Dutch National Annex to EN-EN 1990.
7.10.2.3. Arithmetic value inside water level
In some situations, the inland water level is also uncertain with a certain degree ofdispersion, depending on the water management conducted just before and during
a flood and the orientation of the inland waterway. In many situations the inland
water level is limited, such as with an underlying regulated channel. The
calculation value of the inland water level hbi, d can be determined as follows.
If the inland water level during high water is not known, or not checked, theaverage water level during the winter season can be taken as the starting point
because the water level of the water system during a high water due to seepage andpossible decrease of discharge capacity will almost always be higher. If there is alimited summer and winter level can be assumed the winter level. However, it must
be verified whether the water level at the work of art cannot be reduced as a resultof fanning and grinding. Coordination with the manager regarding the experienceswith recent flood periods is desirable in determining the calculation value of theinland water level.
If the inland water level is uncertain and one has statistics during high water, it isalso possible to work with an exceedance probability of hbi, d, whereby the inland
water level is considered as the non-dominant water level within the decay load:

171

Here is:Lowest inland water level compared to NAP in a period of one

hbi

year [m]hbi, dCalculated value of the inland water level in relation to NAP [m]Φ (...)

Standard normal distribution

Φ-1 (...)

Inverse of the standard normal distribution

P (V> Vd)

Exceeding probability of the calculation value of the expiry tax ina period of one year [-]This approach assumes that the load effect of the outside water level is dominant,which is almost always the case.
7.10.2.4. Recommended calculation values for verifications based on the Building Decree
The 'standard method' (Figure 36) and the table below can be used for the
purposes of the verification in accordance with the Building Decree with 6.10bfrom the NEN-EN 1990. Here, the exceedance probabilities of the calculation
values of the decay and wave load must be determined with the 1-annual tax
statistics for the last (mostly 100e) year of life, depending on the reliability
requirement βeis, BB (see paragraph 7.7.2). This is also the case with a dominant
own weight tax.
132 頁
Table 12 Prescribed exceedance probabilities and parameter values according to 6.10b forverification Building Decree
βeis, BB for

P(S>Sd) = Pdb [-]Pndb [-]

reference

Involve on 1-year

Involvement in 1-year

period equal

statistics in the last

statistics in the last year

to lifetime

year of lifeof lifeCC1

3,35,0∙10-4

CC2

3,8

CC3

4,3

Follow-class

KFI*

ξ*

YG*

9,4∙10-2

0,9

0,89

1,35 of 0,9**

9,0∙10-5

6,7∙10-2

1,0

0,89

1,35 of 0,9**1,0∙10-5

4,4∙10-2

1,1

0,89

1,35 of 0,9**※（Rijkswaterstaat, Central government 2018）132 頁より作成。
* value in accordance with NEN-EN 1990 / NB** 1.35 in case of unfavorable working and 0.9 in case of a favorable working weight
The exceedance probabilities in the table have been calibrated taking into account model
uncertainties
172

In case of a verification in accordance with 6.10b, the application of CC3 fromthe Buildings Decree and the use of the fixed failure probability budget (Table
1) and the default N value (= 3); a verification based on the Water Act is nolonger necessary. In that case, the Building Decree is always decisive for the tax
effect Ed, b.
As mentioned earlier, for a verification in accordance with 6.10a, reference is madeto Appendix C. The Casus in chapter 11 contains a practical elaboration of therecommended calculation values based on the Building Decree, see section
11.6.10.
7.10.2.5. Recommended calculation values for verifications based on the Water Act Tax
Statistics in which year of the construction? During the verification on the basis of
the Water Act, when determining the tax statistic, a distinction must be madebetween the situation that the own weight load is dominant (6.10a) and thesituation where the hydraulic load is dominant (6.10b):When checking with a dominant self-weight tax (6.10a) must are based on the
tax statistics in the 1st year of life of the construction. This is different fromverifications based on it Building Decree.

At a verification with a dominant hydraulic load must be based on the tax
statistics for the last (usually 100 th) year of life of the structure. Here thesubtle difference between failure and failure must be be observed, see section
7.4.

Hydraulic load dominantIf the hydraulic load is dominant, the load effect only needs to be determined according to
6.10b. The exceedance probabilities from the 'standard method' (Figure 36) Pdb and Pndb
and the parameter values for the self-weight tax are quantified in Table 13. Pdb and Pndb
must therefore be included in the 1-year tax statistics in the last (mostly 100th) year of life.
133 頁
The values of Pdb and Pndb to be maintained and the partial factor for the own
weight load are given in Figure 37 and Figure 38 respectively as a function of the
failure probability βeis, KW, CON:173

Here is:βeis, KW, CON Failure Chance expresses in a reliability index for structural failureand no failure by overflow/transshipment for a reference period
equal to tref = 1 year [-]. See section 7.7.1.
Φ-1(...)

Inverse of the standard normal distribution

Table 13 Recommended exceedance probabilities and parameter values according to 6.10bwhen verifying Water Act
Parameters

Recommended values

KFI

1,0

ξ

0,89

Ψ0

0,6

YG

See Figure 38

Pdb and Pndb [-]See Figure 37

Involve on 1-year statistics in the last yearof life※（Rijkswaterstaat, Central government 2018）133 頁より作成。
NB1: The exceedance probabilities and the tax factor for the own weight load are calibrated
taking into account model uncertainties.
NB2: The correction of the material factors is incorporated in the Pdb and Pndb. The material
factors in NEN-EN 1992-1999 are based on CC2.

174

※（Rijkswaterstaat, Central government 2018）133 頁より作成。
Figure 37 Recommended exceedance probabilities for decay and wave load Pdb and Pndb
according to 6.10b for inspections based on the Water Act

175

134 頁※（Rijkswaterstaat, Central government 2018）134 頁より作成。
Figure 38 Recommended partial factor for self-weight tax during inspections based on the
Water Act in case of a dominant hydraulic load.
In case of a verification in accordance with 6.10b, the application of CC3 from the
Buildings Decree and the use of the fixed failure probability budget (Table 1) andthe default N value (= 3); a verification based on the Water Act is no longer
necessary. In that case, the Building Decree is always decisive for the tax effect Ed,.

b

Own weight tax dominant
When the constructor estimates that the own weight is 80% or more of the totalload, the verification must also be carried out in the first year of life, whereby thetax effect is determined by 6.10a. Because these are exception situations, thisverification is not explained in the main text but in Appendix C.
In the case study in chapter 11 a practical elaboration of the recommended
calculation values based on the Water Act is included, see section 11.6.12.
7.10.3

Other hydraulic loads
In this section, other hydraulic loads are treated, namely the loads associated with176

turning water in daily situations, when there is a negative gradient and whenturning water in incidental situations. The method for deriving calculation values
for these hydraulic loads has been elaborated on the basis of a fictitious example ofa lock. In the elaboration, use has been made of [Ref. 7.6].
7.10.3.1. Example of lock lock
The lock to be designed in this example is part of a standard route which, according
to the Water Act, has a lower limit value of 1 / 10,000 per year. In the question
specification, CC2 is required with a design life of 50 years.(135 頁)The floor
height of the lock should be at NAP + 3.50 meters. The artwork will connect achannel (inside) with the outside water (outside). The fencing process is stopped
at water levels higher than NAP + 5.00 meters and lower than NAP + 3.00 meters.
The probability of not closing per closing question (Pns) of the outside head isequal to 10-3 per question.
Table 14: lock levels in the example lock locks
Parameters

ValuesLock level minimum

NAP+3,00 m

Lock level minimum

NAP+5,00 m※（Rijkswaterstaat, Central government 2018）135 頁より作成。

※（Rijkswaterstaat, Central government 2018）135 頁より作成。
Figure 39 Schematic representation of water levels example of the lock. The probability
distributions shown are the probability distributions of the annual minima and the annual177maxima of the external water level.
Channel levels
The channel concerns a controlled water system with maintained levels according to Table
15. It is assumed that there is little to no uncertainty regarding these maximum andminimum channel levels, or the calculation value of the water level load by channel water
can be derived directly from these channel levels.
Table 15 Channel levels in the example lock locks
Parameters

ValuesChannel level minimum

NAP+3,70 m

Channel level minimum

NAP+4,30 m※（Rijkswaterstaat, Central government 2018）135 頁より作成。
The outside water
The outside water is a fictional river with an uncertain water level. The lock is in a shelteredlocation so that the wave load is zero. In this example, the annual maxima and annual
minimums of the outside water level are described by Gumbel distributions. Due to climate
developments, the outdoor water distribution in the last year of life will be the worst, hence
the Gumbel distributions for the 50th year of life are shown in Figure 40.
In a design assignment in practice, the water level statistics can also have a different
distribution, or as in most cases a data series from, for example, Hydra-NL. The way inwhich the water level is determined has no consequence for the present method.

178

136 頁Water level statistics for annual maximum, for example, lock
Parameters

Values *Outside water annual maximum

μh,max = NAP+5,00 m Bmax = 0,50 m* Associated with years of metric from the 50th year of life
The annual maximum is described using a Gumbel distribution for maxima (chance of fall):

At which:With:hOutside water level

umax

Location parameter of outside water level annual maximum

Bmax

Decimation height annual maximumγ

Constant van Euler (= 0.577)

μh, max

Average value of the annual maximum※（Rijkswaterstaat, Central government 2018）136 頁より作成。
179

Figure 40 Annual maximum water level statistics in the 50th year of life
137 頁
Water level statistics for annual minimum, for example, lock
Parameters

Values *Outdoor water annual minimum

μh,min = NAP-0,30 m Bmin = 0,20 m* pertaining to annual statistics in the 50th year of life
The annual minimum is described with the help of a Gumbel distribution for minima(probability of failure):

At which:With:umin Location parameter of outside water level annual minimum
Bmin Decimation height annual minimum
μh, min Average value of the annual minimum
μh, min Average value of the annual minimum

180

※（Rijkswaterstaat, Central government 2018）137 頁より作成。
Figure 41: Annual minimum water level statistics in the 50th year of life
7.10.3.2. Calculation values hydraulic load for daily situations
In water situations in daily situations here are frequently occurring load situations
caused by water level differences and waves, where the outside water level is higher
than the inland water level, for example during the protection process.
For flood defense works in primary flood defenses, the outside water level (and thewave conditions) are uncertain with a large spread, as in the example. In daily load
situations, such as during the locking, the outside water level and the wave
conditions are limited, however, with a maximum and minimum safety level in thecase of locks. (138 頁)Since the introduction of the Eurocode in 2012,
Rijkswaterstaat (Directorate-General for Public Works and Water Management)
has signaled that these daily loads (which are limited by the maximum andminimum levels of the ship's level and channel level) are interpreted as variable
taxes, to which the tax factors in the Eurocode are applied (for CC1: 1.35, for CC2:
1.5 and for CC3: 1.65). Such verification is unnecessary and incorrect. The dailywater levels and wave conditions are part of the collection of all possible waterlevels and wave conditions that can occur in a year. The calculation value of the
expiry tax that can occur in a year is already given in section 7.10.2. Anothercalculation value of the outside water level does not have to be considered.
7.10.3.3. Calculation value positive decay on inner head
The decay load on the inner head is caused by the difference between the gully andthe channel level. For the calculation value of the vortex level, the probability of not
closing per closing request (Pns) of the outer head must be taken into account. At
positive times, the calculation value of the channel level can be selected as NAP +3.70 m.
Because the hydraulic load is dominant in relation to the own weight load, a design
verification in accordance with 6.10b is sufficient (see section 7.10.2). As in section
7.10.3.2, therefore, use is made of the 'standard method' for determining the
calculation value of the decay load from Figure 36. Because the probability of
failure of the outer head has an influence on the calculation value of the hydraulicload on the inner head. , this situation will be discussed in detail.
181

Since the wave load is negligible in the example, the calculation value of the decayload is equal to the calculation value of the hydraulic load: P (V> Vd) = P (S> Sd) =Pdb.
In addition, the channel level is regulated so that the uncertainty of the decay load
is fully determined by the outside water level. This leads to: P (h> hd) = P (V> Vd)= P (S> Sd) = Pdb.
The reliability requirement associated with CC2 is a reliability index βeis, = 3.8(over the lifetime), see section 7.10.3.1. In accordance with the 'standard method'and its elaboration for the Building Decree in section 7.10.2.4, the following
calculation values are recommended:
Pdb =P (h> hd)

9,0・10-5

per yearYG

1,0 x 1,35 = 1,35-※（Rijkswaterstaat, Central government 2018）138 頁より作成。
The reliability requirement from the Water Act follows from paragraph 7.7.1:

139 頁
In accordance with the 'standard method' and its elaboration for the Water Act insection 7.10.2.5 (Table 13), the following calculation values are recommended,
given the above requirement:P(h>hd)7,0∙10-5

per year

YG

1,25

-

※（Rijkswaterstaat, Central government 2018）139 頁より作成。
The calculation values resulting from both reliability requirements are close to eachother. In this example only those from the Water Act will be further elaborated.
For the calculation value of the vortex level, the probability of not closing per182

closing request (Pns) of the outer head is taken into account, as follows:

Where ℎd,kolk is the calculation value of the vortex level. In the example, theexceedance probability of the calculation value of the vortex level is equal to:

In the example, the water level statistics are described by the Gumbel distribution
in Figure 40. The calculation value of the outside water level thus follows:

The calculation value of the decay over the inner head is therefore equal to:

The model uncertainty has already been discounted in the 'standard method' insection 7.10.2, so that the load effect Ed as a result of the hydraulic load equals thecalculation value of the calculated decay load.

It is wise to consider the situation in which the outer door has been closed
successfully for the structural design of the inner door. In this case, it makes sense
to make the inner door the decay, whereby the vortex level can rotate
constructively at the same height as the crown height of the inner door. There is agood chance that in case of extreme conditions and a successfully closed exterior
door the water level rises due to wave overtopping over the outer door. The vortex
level can rise up to the crest height of the inner door, after which overflow occurs.
The water level equal to the crown height can be used as a calculation value
without extra safety, since the water level cannot rise.
7.10.3.4. Calculation value negative decay on the outside of the headIn the case of a negative decline, the water pressure on the outer water side issmaller than on the inland water side. In many cases, other turning means will be
used to turn a large negative gradient than for a positive fall. (140 頁)The
183

calculation value of the decay load is the result of a low outside water level in
combination with a high vortex, with the vortex being maximized at NAP + 4.30
meters. This situation does not have to be considered from the Water Act, because
the chance of the combination of the occurrence of a high water within therecovery time (or time for measures) after an extremely low water is considerednegligible. There is a big difference between the risk of failure and the chance of aflood. We therefore only look at the Building Decree below. Since waves do notplay a role in the example, again the calculation value of the decay load isdetermined at an exceedance frequency P (V> Vd) = P (S> Sd) = Pdb. Here again,
the uncertainty of the decay load is fully determined by the outside water level.
Given the above, the calculation value of the decay Vd occurs at the calculation
value of the outside water level hd with an undercutting probability P (h <hd) = P(V> Vd) = P (S> Sd) = Pdb.
In the example it is assumed that the hydraulic load is very dominant over the own
weight load, so that only the load effect according to 6.10b needs to be considered.
As already elaborated in section 7.10.3.3, for the reliability requirement associatedwith CC2, the reliability index βeis, BB = 3.8 (over the lifetime) and the following
calculation values:
Pdb = P(h<hd)

9,0∙10-5

per yearYG

1,0 x 1,35 = 1,35-※（Rijkswaterstaat, Central government 2018）140 頁より作成。
Based on the Gumbel distribution in Figure 41, the calculation value of theexternal water level is as follows:

Of course, this calculation value can also simply be read in the exceedance
frequency line of the outside water level. The calculation value of the decay load,
expressed in meters water column, in case of negative times is equal to:

In view of the application of the 'standard method' for determining calculation
values from section 7.10.2, the calculation value of the tax effect applies again:184

7.10.3.5. Calculation value negative decay on inner head
Negative times are based on the maximized channel level of NAP + 4.30m and a
low vortex level. There will be artillery to NAP + 3.00m. As a matter ofconvenience it is assumed that it is certain that the outer head is closed at outside
water levels below NAP + 3.00 meters (Pns = 0 per question), then the calculation
value of the decay load is:

141 頁
Because we assume a guaranteed closure of the outer head, the uncertainty withregard to the model uncertainty is relatively large in this case and that with regard
to the water level is small. The 'standard method' from paragraph 7.10.2 istherefore not suitable for this tax situation. For this reason, use is made of themethod in Annex C of NEN-EN 1990 which works with the ISO-standardized
influence coefficient for the load αE = -0.7. Conservatively it is assumed that themodel uncertainty is the only uncertain tax quantity, so that the full influence
coefficient of the load αE = -0.7 is applied for the model factor35:

The total calculation value for the expiry tax follows from:

7.10.3.6. Calculation value hydraulic load in incidental situations
Incidental situations are, for example, maintenance work and inspections, wherefor example a lock chamber is drained.
Major maintenance work sometimes requires the drying of the lock chamber. In thedesign phase of the artwork, careful thought should be given to how this should be
done. It is possible to opt for special retarding agents that have been specificallydesigned for drying, such as bulkheads, to ensure that the sluice gates do not need
to be 'unnecessarily' heavily dimensioned. It can also be decided to flood the gully(or construction pit) under extreme conditions in order to relieve the construction
during an approaching high water during the maintenance work or a threatening185

calamity. One has to be sure that the deployment of this emergency measure will
succeed. A risk analysis is also required for this. For example, by using a lower
screed barrier, the chance of success of the emergency measure can be increased.
In addition, restrictions on the maintenance period can also be included in theoperating manual of the object, for example that the lock may only be drained
outside the storm season. Extreme water levels occur less frequently outside thestorm season. The statistics of the extreme outside water levels outside the storm
season do not follow from Hydra-NL or other instruments, an initial estimate canbe obtained by increasing the exceedance probabilities in winter statistics by anorder factor (factor 10). Ideally, however, use is made of local water level data.
In the present example, it was decided to dry the lock with the normal lock gates,
without restrictions at the time of maintenance. In the example it is assumed thatthe hydraulic load is very dominant over the own weight load so that only the load
effect according to 6.10b needs to be considered (see section 7.10.2). The analysis
focuses on the outside of the head and as far as possible aligns with the 'standard
method' for determining the calculation values of the hydraulic loads in section
7.10.2. The method for the inner head is approximately the same as in section
7.10.3.4. In this example, it is assumed at the design stage that the lock should bedrained for 1 month on average every 5 years.
_________________________________
35

In the case of CC3, γsd should be multiplied by KFI = 1.1 and in the case of CC1 divided

by KFI = 1.1.
__________________________________(142 頁)The probability of failure given drying requires a calculation with theprobability distribution of the extreme water level in a random span of 1 month.
Based on independence between months, the probability distribution for a year canbe related to that of the monthly extremes as follows:

For small opportunities, the following applies:

And vice versa therefore applies to the probability distribution of the monthly
extremes:

186

Applied to the example with a Gumbel distribution in Figure 40:

When the external water statistics are described by a data set from, for example,
Hydra-NL, the same procedure as in formula 4.12 can of course be used to obtainthe monthly statistics. Bmax is the same for the statistics of the month and year
extremes (the exceedance probabilities run parallel to small exceedance
probabilities).

Verification according to the Water Act
The Water Act Verification is based on a failure probability for a reference periodof 1 year (Peis, KW, CON), or in each year the failure probability for the drying
situation must be smaller than the failure probability. For the Water Act
verification, it does not matter whether the lock is being drained once every 5
years, 10 years, 20 years, etc. The failure probability for structural failure of thelock in the example concerns:

Translated into a reliability index:

To determine the calculation value of the decay, use can now be made of the'standard method' in Figure 36 and its quantitative elaboration in Section 7.10.2.5(Table 13). From Figure 36 follows P (V> Vd) = Pdb. In the example, the waves
have been neglected.
143 頁
From Table 13 follows:

P (V> Vd,droogzet) = Pdb = 7.0 • 10-5 per year; this is the exceedance probability187

of the decay load when the lock is set dry in a consecutive period of 1 year.
Because the lock is dried for a maximum of one month in a year, the overflow
load on drying with this exceedance is found at a water level with a probabilityof 7.0 ∙ 10-5 in a span of 1 month.
γG = 1,25.

The decay load consists of the water level differential pressure as a result of theoutside water level and the empty lock chamber. The bottom of the lock chamber ismeasured and is at NAP-3.50 meters. The uncertainty of the decay tax is therefore
fully determined by the outside water level. Using the probability distribution forthe monthly extremes follows at P (V> Vd) = Pdb = 7.0 ∙ 10-5 and the calculation
value of the outside water level is:

What results in:Since the model uncertainty has already been incorporated in the 'standard
method':Verification according to the Building Decree
The reliability requirement in this example is CC2, which corresponds to areliability index βeis, BB = 3.8 over the life of 50 years, see section 7.10.3.1. Thisrequirement can be translated into a failure probability in the following way:
On average, the probability of failure per year must therefore be less than:On average, the construction must comply with this requirement every year withregard to the drying situation. This means that in a random year the probability of
failure per year may be somewhat greater, as long as the failure probability isundershot in other years. For water-retaining constructions this is a pleasantmethod of verification, because the probability of failure varies considerably over
the years, see the bathtub curve in Figure 31. Due to climate development, the188hydraulic load and thus the probability of failure in the last years of life is greaterthan in the first part of the life span. An averaging of failure probabilities over theyears makes the verification less stringent.
If this permissible averaging is ignored and the construction must comply with theannual probability every year, the verification is stricter, but the 'standard method'
can be used in 7.10.2 (Figure 36). Because the failure probability for the lifespanfrom the Buildings Decree has been converted to an equivalent annual probability,
use can be made of Table 13 (with Figure 37 and Figure 38) from Section 7.10.2.5.
(144 頁)This shows the relationship between the calculation value of the decay andthe failure probability per year. This relationship has been developed forverifications based on the Water Act, but in this case also for a verification basedon the Building Decree.
To this end, the failure probability must be translated per year into a reliability
index for a year:

From Table 13 follows:
Pdb = P(V>Vd)

5,0∙10-5

per year

YG

1,28

-

※（Rijkswaterstaat, Central government 2018）144 頁より作成。
For the calculation value of the decay tax follows:

What results in:Since the model uncertainty has already been incorporated in the 'standard
method':7.10.4 Permanent taxes
189

Permanent taxes are taxes that do not vary or only vary in size during the reference
period.
7.10.4.1. Own weight construction (parts)
The method described with regard to the permanent load by own weight in
combination with a high or not dominant high water load is described in section
7.10.2.
A permanent load as a result of the own weight is taken into account with a loadfactor Y = 1.35 (CC2, burdensome) if the own weight is the only load source, andthere is no question of a geotechnical construction or the own weight of a liquid. A
factor Y = 1.2 (CC2, burdensome) may be used for the permanent load due to(permanent) liquid pressure. If the permanent load is considered in combination
with other loads (other than high water, see section 7.10.2), a factor Y = 1.2 (CC2,burdensome) must be taken into account. If the load works favorably (relieved), a
factor Y = 0.9 must be used in all the cases mentioned.
7.10.4.2. Ground pressure
For the permanent load due to earth pressure on geotechnical constructions suchas dikes, embankments and sheet piles, where the weight of the ground occurs as aload, but also plays a role in the soil mechanical strength calculations, the loadfactor must be Y = 1.0 (stressful and relieving) be asked. (145 頁) It is importantthat both the final situation and the construction phases are considered.
7.10.4.3. Groundwater pressure (also increasing force)
The groundwater level near flood defense structures will generally varyconsiderably with the outside water level. In that case the calculation value of thegroundwater pressure is derived from the calculation value of the occurring decay
in accordance with paragraph 7.10.2.
7.10.4.4. Deformations of subsurface/settlement
The characteristic settlement is calculated by assuming the characteristic values forthe loads and the soil properties. Locally, at least the difference in settlement must
be taken into account in the order of 50% of the maximum settlement.
7.10.5

Variable loads
190

Variable taxes are taxes that vary substantially over time. For loads due to internaland external water levels and wind waves see 7.10.2.
7.10.5.1. Flow (including any vibrations caused thereby)
In this section the currents are treated over the artwork as a result of a decline.
Flow caused by ships is dealt with in section 7.10.5.3. Flow due to a decay on theflood defense in the situation that it should have been closed (after failing closure)is regarded as a special tax. This flow load is dealt with separately in section
7.10.6.1.
The load by flow is linked to the flow rate. Flow loads can occur during the openingof the barrier, the closing of the barrier, and during high water during leakage gaps
and during transfer and overflow. This concerns the load on the work of art, on soil
protection as well as on gates and doors. Vibrations due to flow must be avoided asmuch as possible. In particular feedback vibrations (liquid - construction
interaction) can lead to very rapidly increasing loads on gates and doors and on
moving works. The prevention of vibrations as a result of too large an overflow rateis discussed in section 5.3.4.
The calculation value of the flow load at high water must be determined on thebasis of the calculation value of the decay in accordance with paragraph 7.10.2. The
calculation value of the flow load as the dominant load in the other situations isdetermined by combining the representative value, the flow rate that is exceededon average once every 50 years, with a load factor of 1.3. The representative valueof the combination value of the flow load is determined at the flow rate that isexceeded on average once a year.
7.10.5.2. Ship waves
Ship waves are relatively short-lived and are not expected to generate dominantloads during high water. Under standard conditions no or only very limited
shipping takes place. (146 頁)After the characteristics of the waves caused bypassing ships can be caused in the same way as for wind waves representative loadon the structure. For the calculation of the wave load is referred to Annex D. The
calculation value of the ship wave load is calculated after multiplication by the tax
factor. In Table 11 a value of 1.3 is given for both the dominant tax as the
combination tax.
191

7.10.5.3. Shipping current
Currents caused by ships are included in the assessment of the water retention
capacity not considered because it is under normative shipping is barely involved.
For normal However, in business situations, these taxes can play a major role.
Regarding currents caused by ships, there are two types distinguished, namely the
return flow and the screw-jet flow. Both become expressed in terms of flow rates.
For the calculation of this movements is referred to the Construction service
publications Design of locks [Ref. 7.20] and the Granular Design Manual Soil
defenses [Ref. 7.19]. The flow rates thus calculated can be considered as
calculation values for both the dominant and the combination load.
7.10.5.4. Tensile forces.
The truss forces of ships may, via bollards, provide a tax on the water-retaining
parts of works of art. If the (local) collapse of a structural component due to bollard
forces the water retaining function of the can jeopardize the artwork, also serveswith design inspections of bollards water safety.
The truss forces are mainly determined by the size of the ship, the water flow andwind load. CUR report 166 Sheet pile structures are for both seagoing vessels andinland navigation vessels, calculation values for bollard forces given as a function ofa measure of ship size (for seagoing vessels the water displacement and for inland
vessels the class of ships). Account must also be taken of the design ofRijkswaterstaat (Directorate-General for Public Works and Water Management)
objects taken into account the Guidelines for Designing Artworks [Ref. 7.11].
7.10.5.5. Traffic taxes
Traffic taxes are viewed from the point of view of water safety alone relevant
insofar as they can be present under high water conditions, then can lead todamage to water defenses that cannot be repaired quickly structural components ormovement works. The starting point is that all occurring traffic taxes are covered in
the design and under normal circumstances they therefore do not need to beverified. Supplementary must go to maintenance situations. For example, thetraffic load of a crane in case of a door change of a lock.

192

7.10.5.6. Temperature
Temperature loads do not have to be considered when assessing the flood defense
capacity, because under normative circumstances none extreme temperatures(both high and low) are to be expected.
147 頁
7.10.5.7. Wind pressures
The calculation of the representative value of wind load by wind pressure, windsuction and over- and under pressure takes place according to NEN-EN 1991-1-4.
7.10.5.8. Taxes from the movement work
Taxes with standard opening/closing movements will be surrounded with little
uncertainty. Restoration measures from chapter 4 Not closing can result in certain
loads under (near) high water conditions. These are highly situation-dependentand must be specified by the designer.
7.10.6

Special taxes
Disasters are events that can occur with a relatively small chance and that candirectly or indirectly lead to the occurrence of special taxes. If the chance of acalamity is sufficiently small (smaller than the failure probability for structural
failure of the artwork), these special taxes do not have to be explicitly taken into
account. When rare taxes can be covered without or at a small additional cost, thenthat is obviously to be considered.

7.10.6.1. Flow in case of non-closing
In the event of failure of a high water seal, high flow rates through the artwork canlead to damage to the soil protection and thus ultimately to undermining and thestructural failure of the artwork. If the design has been verified against the failure
probability for not closing in accordance with Chapter 4, this load situation iscorrectly given in the correct manner.
7.10.6.2. Accept
Hydraulic constructions can be hit by ships where parts of the structure collapse.
For the flood risk, specifically the acceptance situation on water-retaining
construction components is of importance, as a result of the collision a flooding canoccur. A flood can occur if a high water occurs within the recovery time of damage,but also when no high water is present and the hinterland is a deep polder.
193

The chance of accepting water retaining structures during or just before a highwater level is very small because waterways are usually blocked in time. In somecases, however, lock locks at higher water may still be in operation. When thesecond turning means is hit during high water, a flood can occur.
During the verification, the chance of attacking P (accepting) is combined with thechance of constructive failure given an acceptance tax P (Settling | Accepting). In
the case of a verification based on the Water Act, the likelihood of exceeding the
maximum permissible inflowing volume of water, either from the compilation
criterion or from the soil protection criterion, after the collapse of water-retaining
components P (Vin> Vmax | Succession) be taken away. So there must be:

148 頁
If the chance of a collision is already smaller than the constructive reliability
requirement, the construction meets the requirement immediately.
The parameters in the above formula are a function of many stochastic variables,such as the sailing speed, angle of attack, mass and dimensions of the ship, etc. The
arrangement of the outer port and lock chamber is an important precondition forthe chance of acceptance. The acceptance tax is therefore unique for every
situation. This should therefore be considered tailor-made, with location-specificdata. A generic method for determining the calculation value of the acceptance tax
is not available.
Where a real acceptance risk is expected, the solution can also be sought inmeasures to reduce the chance of (serious) collision damage. One can think ofanother establishment of the outer harbor so that ships are forced to lower sailing
speeds or to create an acceptance protection.
For additional information, please refer to NEN-EN 1991-7 with national
appendix, Guidelines for Design Artworks (ROK) [Ref. 7.11], Recommendationsof the Committee for Waterfront Structures Harbors and Waterways - EAU 2012
[Ref. 7.13], Manual for the quantitative determination of the acceptance risk of194

movable objects in the waterway (part of the PRA, RWS) [Ref. 7.14] andHandbook Design of locks [Ref. 7.20].
7.10.6.3. Earthquake
For guidelines for the determination of earthquake loads, use must be made of thelatest state of knowledge in this area.
7.10.6.4. Explosion
Explosion safety of operating rooms and the like can be verified according toEurocode EN 1991-1-7. The load caused by explosions of ships with hazardous
substances is normally neglected.
7.10.6.5. Ice
In every design situation an estimate of the possibility of an ice load has to be
made. Ice-load is not explicitly mentioned in the Buildings Decree, but here, thedesign of locks and similar constructions must be taken into account. Indicative
calculation values can be found in CUR Report 166 Sheet pile constructions [Ref.
7.10]. In the Guidelines for the Design of Artworks (ROK) [Ref. 7.11], further
draft recommendations for works of art by Rijkswaterstaat (Directorate-Generalfor Public Works and Water Management) are given.
7.10.6.6. Obstacles during closing
If an obstacle prevents the movement of the door, this can give rise to tensions in
the construction that deviate strongly from the normal (extreme) loads. This tax
should be considered in relation to the movement work. From the point of view of
the Water Act, it must be assessed whether this does not give rise to long-term
damage, non-availability and possibly a flooding.
7.10.6.7. Vandalism and sabotage
Attention should be paid to measures against vandalism and sabotage.
149 頁
7.11

Strength

7.11.1

Calculation value strength construction
As indicated in section 7.8.4.2, the calculation value of the strength Rd fromformulas 6.6a to 6.6c in NEN-EN 1990 follows. The partial material factors (YR)195

that are used in this process follow from the material-bound Eurocodes (NEN-EN
1990 t / m 1997) and in some cases from other directives. An overview is given
below.
Table 16 Overview of the most important construction elements and mechanisms(excluding movement works)
Part of hydraulic structure

Mechanism of limit state

Prescription/guideline-concretestrength/stability

NEN-EN 1990-1991-1992-steelstrength/stability

NEN-EN 1990-1991-1993-wood

strength/stability

NEN-EN 1990-1991-1995-brickwork

strength/stability

NEN-EN 1990-1991-1996-construction

strength/stability

NEN-EN 1990-1997-steel foundation

strength/deformation

NEN-EN 1990-1997-pile foundation

strength/deformation

NEN-EN 1990-1997-ground bodystability/deformation

NEN-EN 1990-

Turning means, moving
works and superstructure

Foundation and subsurface

1997/Guideline River dikes-dam wallstrength/stability

NEN-EN 1990-1991- CUR
report 166 [Ref.
7.10]- retaining wallstrength/stability

NEN-EN 1990-1991- CUR
report 166 [Ref.7.10]

Edge constructions-well screens

strength

CUR report 166 [Ref. 7.10]-soil protectionwash away

Rock manual, Scour manual-filters/membranes

Internal RWS documents※（Rijkswaterstaat, Central government 2018）149 頁より作成。
7.11.2

Background of the partial material factor
The partial material factors are partly based on probabilistic considerations andpartly on historical or empirical. For materials such as steel and steel concrete,
196extensive background documents exist at European level with a description of test
results and a related statistical elaboration. For other materials, including soil, thelink between the intended and proven safety is often less strong. For each material
and each load (combination) there is the possibility to calibrate the specific partial
factors or coefficients, in order to achieve the required level of reliability. However,this requires specific expertise in this area.
7.11.3

Degeneration
When designing, one should take into account aging and damage, such as:Steel: fatigue and corrosionConcrete: damage, carbonation, chloride penetration, alkali-silica reaction,
freezing/thawing, et cetera

Wood: fatigue, creep, deterioration

150 頁
Under aging means mechanisms that slowly reduce the strength. On balance, thereliability also decreases. Because the artwork must still meet the reliability
requirements at the end of its design life span, the design must be taken into
account especially in the case of hard-to-replace steel parts.
Common methods to prevent, inhibit or obviate aging include preservation (anticorrosive coating), cathodic protection (steel) and dimensioning with a certain
over-thickness. In the case of steel, the corrosion rate can vary greatly dependingon the environment and steel quality. A first indication can be derived from CUR
report 166 sheet pile constructions [Ref. 7.10]. For Rijkswaterstaat (DirectorateGeneral for Public Works and Water Management) objects are in the Guidelines
for Designing Artworks (ROK) [Ref. 7.11] included even greater corrosion
surcharges.
The decrease in reliability due to the aging mechanisms can be reduced byinspection and maintenance. If this pays off, maintenance can also be organized ona probabilistic basis. One must then search for state parameters (or guideparameters). These are measurable construction parameters that describe thecondition of a flood defense. During the lifespan of the construction, further
information can be obtained about these variables by inspection. The reliability
index can then be adjusted via Bayesian processing of this data in a reliability
197analysis. Based on this, it is then possible to decide on maintenance measures.
7.11.4

Fatigue
Fatigue can occur if a load, such as pressure, tension, bending, twisting or
combinations thereof, occurs repeatedly. In general, a number of tax changes thatare roughly between a thousand and a few millions in life expectancy should beconsidered. In hydraulic structures, fatigue damage can occur, especially in doors
and gates, and in connection with the movement works thereof. This is due toloads caused by wind waves or vibrations through the flowing water. Loads by wind
waves can be limited by, for example, the screening of an outer harbor. Loads
caused by wave impacts can be prevented by the design of the structure, forexample by avoiding angles enclosed with a sliding construction. Vibration by flow
can be prevented as much as possible by, for example, choosing the geometry of
the sliding edges correctly. Further information can be found in, for example,
Dynamic behavior of hydraulic constructions [Ref. 7.9].
In order to assess whether or not a construction will collapse under a variable load,
the following aspects are important:The nature of tax changes. For example, a construction generally better
withstands a variable load if the load direction does not change sign (a socalled jump load) than if it does (a varying load). Incidentally, this does not
apply to steel constructions;

The number of tax changes. Fatigue damage can occur in small numbers ofchanges (≥ 1000), but this usually does not immediately lead to failure.
Furthermore, it appears that if a construction can withstand several million
load changes, there is no risk that the construction will collapse purely due tofatigue if the conditions remain the same;The amplitude of the load changes: the smaller the amplitude, the smaller therisk of fatigue;

151 頁


The material and the design of the structure. The design and the surface
condition can give rise to stress concentrations. Sharp cross-section transitions
in constructions, certain types of welds etc. are places where the construction
will collapse as a result of fatigue.

In 2017 the version of NEN 6786 part 1 was released which gives the requirements
198

and preconditions with regard to fatigue for movable bridges. This standard canalso be used for the design of hydraulic constructions, together with NEN-EN1993
parts 1-9 and the additional ROK provisions [Ref. 7.11].
In addition, the design must also be verified in accordance with the Water Act,
whereby the reliability verification must take place in the last year of life. NEN
6786 Part 2 will be released in the near future and will be written specifically forhydraulic constructions.
7.12

Concrete design recommendations
The foundations and concrete structures of hydraulic constructions are generally
designed for a planned lifetime of 100 years. Because in the past robust design has
been developed, many constructions that are already much older function
constructively just fine. In general, the costs of more robust dimensioning are thenstrictly required for small and medium-sized structures, for which this manual iswritten, limited compared to the earlier replacement. For structural components
such as steel doors or movement works, however, a design life that is considerably
shorter than 100 years can be optimal.
At the moment there is a lot of uncertainty about the way in which the climate willdevelop and with which seawater rise and extreme discharges we have to take into
account in the future. In addition, safety standards are updated periodically, suchas recently with the introduction of the new Water Act (2017) and the new
Building Decree (2012), which in most cases led to more stringent constructive
requirements. The use of objects can also change. In this way ships are becoming
larger and the sailing intensity of waterways changes over time, so larger
dimensions or more efficient systems may be needed.
It is recommended to design on the basis of a life-cycle approach, taking into
account as much as possible these future developments. Because there is a longtime horizon, the changes in load, strength and use are often difficult to estimate.
It therefore seems sensible to replace or strengthen components that are not easy
to use, such as foundation, sluice floor and some superstructure components, tomake robust choices and to make construction components larger and stronger
than at present, with current knowledge is considered strictly necessary as long as
it does not require disproportionate investments.
199

7.13

References[Ref. 7.1]

WTI 2017 Key rules for works of art - Test track report Strength andstability of point constructions, 1220087-004-GEO-0007, Bree, B.
van, Delhez, R., Version D1, December 2015

[Ref. 7.2]

Foundations for flood protection, Expertise Network Flood risk
management (ENW), 2016

152 頁
[Ref. 7.3]

Calibration test requirement structural failure under high water loadfor RBK-NAT, TNO 2017 R10778, June 2017, Nadieh Meinen,
Raphael Steenbergen, Ruben Jongejan and Arnaud Casteleijn[Ref. 7.4]

Results calibration partial factor for self-weight load for RBK-NAT,
TNO 2018 R10541, May 2018, L.C. la Gasse, N. Meinen, R.D.J.M.
Steenbergen[Ref. 7.5]

Assessment of the structural safety of hydraulic structures according
to the Building Decree and the Water Act, TNO 2014 R11674, May
2015, Ruben Jongejan and Raphaël Steenbergen[Ref. 7.6]

Reconciliation Guideline Works of Art and Eurocode; activity 2: loadfactor daily conditions, Deltares report 1204875-002-GEO-0011,
March 2, 2012, concept, E. Calle and A.C.W.M. Women's field[Ref. 7.7]

CUR 190, Opportunities in civil engineering, part 1: probabilistic
design in theory, July 2002

[Ref. 7.8]

Dictation Probabilistic design, TU Delft 1987, A.C.W.M. Female
fielder and J.K. Vrijling[Ref. 7.9]

Dynamic behavior of hydraulic structures, P.A. Kolkman and T.H.G.
Jongeling, Ministry of Transport, Public Works and Water
Management, Public Works and Water Management, Road andHydraulic Engineering, 1996

[Ref. 7.10]

CUR report 166 Sheet piles (part 1 and 2) 6th edition, 1 October
2008[Ref. 7.11] Guidelines for Art Works (ROK 1.4), Rijkswaterstaat (DirectorateGeneral for Public Works and Water Management), April 2017
[Ref. 7.12]

Recommendations of the Committee for Waterfront Structures
Harbors and Waterways, EAU 2012

[Ref. 7.13]

Acceptance risks for lock gates, Report Q1399, Delft Hydraulics
Research Laboratory, A. Free castle, 1992
200

[Ref. 7.14] Guide to performance-based risk analyzes (PRA), Guide to thequantitative determination of the acceptance risk of movable objects
in the fairway, Rijkswaterstaat (Directorate-General for Public Works
and Water Management), 5 April 2017
[Ref. 7.15]

Random seas and design of maritime structures, 3rd edition,
Yokahama National University, Yoshimi Goda, 2010

[Ref. 7.16]

Collegehandleiding Windgolven, TU Delft, J.A. Bats

[Ref. 7.17]

Collegehandleiding Korte waves, TU Delft, J.A. Bats

[Ref. 7.18]

Handbook of Port and Harbor Engineering, T.P. Tsinker, Chapman& Hall, 1997

153 頁
[Ref. 7.19]

Rijkswaterstaat (Directorate-General for Public Works and Water
Management) Construction service, 1995. Guide to Designing
Granular Soil Defenses behind Two-Dimensional Outlet
Constructions[Ref. 7.20]

Rijkswaterstaat (Directorate-General for Public Works and Water
Management) Building Service, 2000. Design of locks. Ministry ofTransport, Public Works and Water Management, Directorate
General Rijkswaterstaat (Directorate-General for Public Works andWater Management).

[Ref. 7.21] Wave loads in ports and protected areas, National Institute for Coastand Sea / RIKZ, 2004
[Ref. 7.22]

J.W. Van der Meer, K. d 'Angremond & J. Juhl (1994) Probabilistic
calculations of wave forces on vertical structures. Proc. 24th ICCE,
Kobe, Japan.

201

155 頁

8

Connection constructions

8.1

Introduction

8.1.1

Purpose and definitions
The purpose of a connection construction is to prevent external erosion at theinterface of artwork and subsequent ground body as a result of wave and flow loads.
This will prevent the stability of the flood defense at the location of the connection
between the artwork and the ground body will be reduced, possibly resulting in a
progressive breach and flood consequences.
External erosion at the location of the connection of the artwork and the adjacent
ground body can occur on the outer slope, the crown and the inner slope. In
principle, the possible failure mechanisms are equal to the dike failure mechanisms,
grass erosion crown and inner slope and all dike failure mechanisms with respect to(outer slope) coatings.
The connection construction is understood to mean the entire transverse andlongitudinal profile of a ground construction in its deviating shape, at the transition
from the work of art to the undisturbed dike. Figure 42 shows the most importantcomponents.

※（Rijkswaterstaat, Central government 2018）155 頁より作成。
Figure 42 Principle diagram of connection construction

202

The connection construction is a physical constructive measure. It can containvisible parts and invisible parts, for example a cover and a screen. The impact zone
to the adjoining dike cladding (for example a grass cladding), where the effects ofthe physical measure on the subsequent cladding are still significant, also belongs
to the connection construction.
8.1.2

Delimitation
For the safety verification the higher connection constructions are important,which are necessary for the proper functioning as high water barriers at highoutside water levels over the flood defense and / or high waves. These are usually
above water in normal conditions, in the wave run-up zone and in the wave
transfer zone. Figure 43 gives some examples.

156 頁
Lower connection constructions (often under water or in the wave impact zone
with more or less daily loads) usually do not have a high-water function and / orare not subject to significant stress during high water. However, care must be taken
to ensure that damage that has occurred during high water cannot be aggravatedand lead to flooding.
In addition to connecting structures between the dike and the artwork, thetransitional constructions between the artwork and the front or bottom of the soil
are also important. This concerns, for example, the transition construction from alock floor to the soil protection structure, or from the soil protection structure to
the unprotected soil. Such transitional constructions (soil protection constructions)are discussed in chapter 9 Soil protection.

203

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）156 頁より作成。
Figure 43 Examples of high-lying connection structures to the adjacent dike cladding(source: Guide to connection constructions ([Ref 8.1])):
a - Connection wall construction and stone covering bellows Ramspol.
b - Connection to the top wall protruding wall construction, sluice at Bath.
c - Connection of wing wall to slope covering, sluice at Bath.
d - Connection with height difference around artwork, Lorentz locks.
The connection of the dike body to non-water retaining objects, such as stairs, is
not treated in this manual.
8.2

Requirements
A connection construction is part of the dyke project and therefore has a floodprobability contribution. If use is made of the fixed failure probability budget(Table 1) for assigning failure probability to failure mechanism, however, no
failure probability space for connection constructions appears to be defined. As
204explained in section 8.1.1, connection constructions fail according to the same
failure mechanisms with regard to external erosion as normal ground dikes, only inmany cases the geometry is different from ground dikes. (157 頁) As a result, thefailure mechanisms of connection constructions can be accommodated in themechanisms - grass, erosion, crown and inner slope and all dike failure mechanics
with respect to (outer slope) coatings - and the corresponding failure probability.
The reliability requirement from the Buildings Decree can also be relevant forconnection constructions when it concerns construction components or a retaining
structure.
For the design verification of a connection construction to an imposed failure
probability, the schematization of the limit state function (test or design rules)
must also be known, or the relation between the strength (R) of the connection
construction and the occurring hydraulic load36 (S). Because of the many possible
types of connection constructions and lack of knowledge and research with regard
to these constructions, no default limit state functions are available, as is the case instructural mechanics.
In practice, a connection construction is not subject to a failure probability fromthe Water Act but a relative requirement is used:
A connecting structure must be designed, dimensioned, executed andmaintained in such a way that it is not attenuated during the intended
planning period with respect to the adjacent dike body, assuming that thisadjacent dike body at least meets the applicable requirements during theplanning period.
The failure definition is as follows:
The initiation of the collapse process by local external erosion of the outer
contour of the dyke body, as a result of which (progressive) breachformation occurs leading to substantial damage and / or casualties(flooding). This breach can consist of the instability of the artwork, thewashing away of dyke material or a combination of these two.

205

The above definition means that there must be such an erosion of the outer
contour that this may lead to flooding consequences. The beginning of failure canbe seen as the first erosion of the connection (for example eroding lining at thelocation of the connection), after which actual failure occurs if this leads to further
erosion of the dike or the instability of the work of art. This means that the positive
contribution to the strength of a (back-walk) screen can be included in theconsiderations.
Incidentally, it should be noted that erosion of the connection construction issomething other than erosion as a result of backwardness (internal erosion), in
which erosion is initiated in the dike body.
8.3

Schematisation________________________
36

Indicated as F in NEN-EN1990.

________________________
158 頁
8.3.1

Conflict processes
Connections between ground dikes and rigid structures such as structures arevulnerable to external erosion processes, caused by locally increased transhipment
rates, irregular geometries and the local effects of very turbulent flow. With
connection constructions, there is often a question of:

Surface erosion and gully formation as a result of run-off surface water thatconcentrates on the interface between the structure and the dike.

Surface erosion at the connection due to local turbulent flow caused by thegeometry of the structure or by roughness differences.

Initial damage to connection structures can lead to higher loads and thereby
initiate a self-accelerating damage process, as a result of which connection
structures are maintenance and failure-sensitive. For example, due to insufficientcompaction during execution or by entry by sheep, height differences between
artwork and adjacent soil body can occur, as a result of which wave run-up andovertopping will concentrate, causing stronger erosion. The erosion holes cause
more turbulence to occur, as a result of which the erosion increases further, etcetera.
206

8.3.2

Design verification
The robustness of the design of a connecting structure can be determined by arelative comparison of load (S) and strength (R) with respect to local external
erosion of the outer contour with the load and strength of a reference cross-sectionof the dike body, provided that this reference cross-section at least meets thedesign requirements. In this context reference is made to the cross section of thebasic body outside the area of influence of the artwork (see Figure 42). As long as
the relative increase in load at the location of the connection construction (DS) is
less than or equal to the relative strength increase of the connection construction(DR), the connection construction is sufficient.
The approach for the robustness determination of a connection construction
contains the following two components:
A. Effects that are the direct result of the design, being the design anddimensioning of the connection construction (also called primary effects).
B. Effects entailing the indirect consequences of execution, management andmaintenance as a result of the detailing (also referred to as secondary or longterm effects).
Both effects affect both strength and taxes. The theoretical approach for design
verification is shown in the diagram in Figure 44.
It should be noted that the theoretical verification models are missing for
substantiation of design choices. From that point of view, expert judgment mustthen be used. Use can be made here of experiences with existing connection
constructions.

207

159 頁※（Rijkswaterstaat, Central government 2018）159 頁より作成。
Figure 44 Conceptual approach of robustness determination of connection construction.
Based on [Ref. 8.1]
Explanation:DesignFor the verification of the connection construction, both the transverse profileand the longitudinal profile are important, including the impact zone to theadjacent cross-sections of the dike covering. Points of attention:− Provide sufficiently detailed detailing of the connection construction,
including the transition to the work of art and to the adjacent dikecovering.
− Provide clear basic principles and requirements for implementation,
management and maintenance.

Finding definition
The initiation of the collapse process by local external erosion of the outer
contour, as a result of which further breaching will occur. This breach can
208consist of the instability of the artwork, the washing away of dyke material or a
combination of these two. Points of attention:− Check whether this approach can be applied here. Be alert to other or
additional failure mechanisms that can occur at transitions caused bywater-related loads or secondary loads.
− Consider possible additional effects due to concentrated groundwater flow
and / or internal erosion.


Reference
The reference is the adjacent dike construction (including coating), locatedoutside the impact zone of the connecting structure. Points of attention:(160 頁)− Provide a clear, well-founded choice for the reference profile and thereference situation.
− Find out what the dominant design load is at the location of the reference
profile.
− Determine in advance what is taken as reference strength: the theoreticaldesign strength or, in case of excess strength, the actual strength.
Adjustment of taxes by primary effects (ΔSprimary)
The overall design of the artwork is often of great influence on the loads onconnection constructions. Due to an unfavorable design of the discontinuity,
considerable load-increasing effects can occur. Conversely, due to a favorable
design, the load on the connecting structure can also be considerably reduced.
Points of attention:− Check how the load is reduced or with which tax increase must be taken
into account in relation to the reference.
− Take care when kinking in the slope (for example, the connection to avertical wall). The load here is both high due to wave run-up and theconcentration of the power attack at the interface (jet erosion).
− Simple analytical methods to determine the increase in flow rates atconnections are missing and the current design guidelines are mainly
based on practical experience and field observations. Simple approaches
without waves already show that the flow rates in the zone next to avertical wall can almost be doubled ([Ref 8.4]). The waves also make the209flow pattern even more complex. Due to this complexity theoretically inmany cases advanced modeling is necessary to determine the occurring
flow velocities and the stability of the connection construction. In
practical terms, it means that the strength of the protective structures inthe zone next to the structure must often be considerably greater than thereference strength of the lining on the adjacent dike.
Adjustment of strength due to primary effects (ΔRprimary)
The primary effect of the connection construction on the strength of the outer
contour is caused by the interruption of the coating next to the structure. In
terms of strength, the starting point in the design practice is that the strengthof the solution must be greater than the strength of the outer contour that isinterrupted. Points of attention:− Avoid geometrical discontinuities, such as sudden height changes.
− Avoid discontinuities in properties, such as sudden roughness / orpermeability transitions.



Adaptation of loads by secondary effects (ΔSsecundair)
A faulty execution or poor maintenance can lead to secondary effects on theload on site of a discontinuity. Points of attention:− Ensure that turbulence is prevented by settling differences in linings, bymaking the heights close to each other and sufficiently compacting thesubstrate.
− Provide a durable sand-tight connection. Lack of or premature failure can,for example, cause extra, increased pressure of exiting groundwater over
time.

161 頁


Adjustment of strength due to secondary effects (ΔRsecundair)Interrupting the outer contour with a connecting construction can indirectly
have additional negative effects on the strength of the outer contour, forexample through long-term effects such as settlement. This is largely
determined by the detailing. Points of attention:− Take into account long-term effects, such as settlement. Ensure that theconnection construction can follow the resulting difference, without lossof connection.
210

− Pay sufficient attention to the implementation. Prevent poorly compacted
clay, insufficient clamping or other imperfections during construction, by
proper execution instructions and inspection.
− Consider possible complications for management and maintenance. For
example, the grass mat next to the connecting structure is more difficult
to reach for mechanical mowers, so that the compaction of the top layer
will remain less good in the long term.
− Zones in the shelter of objects are often attractive to animals, so thatweakening can occur through grasslands (mice, moles) or through more
intensive access (sheep).
− View the possibilities to respond to any adverse effects of the design inthe design. For this it is necessary to know the way of implementation.
Termination or influence zone
The termination is formed by the influence zone. The location and design
requires separate attention. Points of attention:− Ensure that the transition between connecting structure and undisturbed
dike body is carried out carefully, so that this cannot lead to a weak spot at
the location of this transition.
− Carefully consider how this can become a weak spot when designing thistransition.

8.4

Principle solutions
Figure 45 gives an overview of some available principle solutions. See below [Ref.
8.1]. There are no examples available where the robustness has been determined ina concrete application.

※（Rijkswaterstaat, Central government 2018）161 頁より作成。
211162 頁

construction※（Rijkswaterstaat, Central government 2018）162 頁より作成。
Figure 45 Examples available principle solutions for connection constructions (source: [Ref8.1]):
a - on brick set, penetrated tapered blocks on geotextile and gravel suitcaseb - on asphalt cladding, membrane loop filled with mastic or bitumenc - on upholstery, with bitumen-filled membrane foldd - on open stone asphalt cladding, geotextile on sand asphalte - from concrete wall or steel sheet pile on asphalt cladding, mastic paddingf - concrete wall on grass cladding, anchored porous permeable medium
g - concrete wall on grass cladding, anchored geotextile

212

8.5

References[Ref. 8.1]

Guide to connection structures, WTI 2017 Cluster Keystroke
Works of Art, Deltares report 1220087-006-GEO-0002, version
D1, July 2015.

[Ref. 8.2]

[IAHR 2015] Transition structures in grass covered slopes or
primary flood defenses tested with the wave impact generator.
Paul van Steeg et al., IAHR 28 June - 3 July, 2015, The Hague,
The Netherlands.

[Ref. 8.3]

[AO 2014] Attendance to (building blocks for) design oftransitional constructions. Fugro report 1213-0077-000, March
5, 2014.

163 頁[Ref. 8.4]

[ILH 2013] The International Levee Handbook. ISBN 978-086017-734-0, Ciria, London, 2013.

[Ref. 8.5]

[ENW 2012] Post-flood investigation in the Lower Chao Phraya
River Basin; Findings of the Thai – Dutch Reconnaisance Team.
ENW rapport, May 2012.

213

165 頁

9

Soil protection

9.1

Introduction
A bottom defense protects the soil against erosion and is located on both theoutside and the inland side of the hard construction. In relation to high water safety,
the soil protection is taxed in the event of flow through the (unjustified) barrier(see chapter 4 Do not close) or the closed barrier (see chapter 5 Height). Soil
erosion on the inside of the artwork can ultimately lead to the undermining of theartwork. In order to guarantee the stability of the artwork within the lifetime andgiven a permissible failure probability, any erosion must take place sufficiently far
from the structure or be prevented entirely. In order to realize this, soil protection
is being constructed in practice which must meet a number of requirements.
The most important constructive requirements for soil protection relate to:Stability (see section 9.4)



Horizontal dimensions (see section 9.5.2)

Vertical structure (see section 9.5.3)

Flexibility in relation to transitions and connections (see section 9.5.4).

Other requirements of less constructive nature are for example:
Inspection and maintenance requirementsEnvironmental requirements

Implementation requirements

In this chapter, the focus is on the constructive aspects. It should be noted that in adesign verification to the Water Act requirement, only the soil protection on theinside of the structure is considered to be under the specific load due to a highoutside water level and/or high wind waves. Other taxes, however, are often
dominant and usually determine the dimensions of soil protection. However, thisfalls outside the scope of this manual; for this reference is made to other design
documents. In this Work Guide the soil protection is considered as a given; therequired dimensions are determined on the basis of the requirements from otherfunctions of the artwork than water-retaining.
9.2

Types of soil protection214

In practice, a multitude of types of soil protection and materials are used. The tablebelow gives an overview of the most common types of soil protection.
Table 17 Overview of various common types of soil protection
Type of soil protection

Material typeCalculation method(most common)
Granular (whether or not

Rubble stone

Shields, extensive

on geotextile)

Snails (steel snails,

Shields for rays

phosphorescent slag)
Coherent

Pilarczyk

GravelEscarameia and May

Block mats

Pilarczyk
Escarameia and May

Open stone asphalt matsNo model available; model

Granular material

research necessary per

penetrated with asphalt or

application

colloidal concrete
Asphalt mastic slabs
Stone structures
Composites

Concrete pillars

Pilarczyk

Basalt columns

Escarameia and May

Gabions

Pilarczyk

Stone mattresses

Escarameia and May※（Rijkswaterstaat, Central government 2018）165 頁より作成。
166 頁
Different types of soil protection are often calculated with the same stability
formula, whereby the type of soil protection is modeled by a value associated withthat soil protection for a specific parameter in this formula. There are several
stability formulas, the outcomes of which are not always in line with each other.
This has partly to do with the sensitivity of the turbulence factor in the different
formulas, but can also be the result of possible extrapolation (or the values to be
filled in of the different coefficients do not correspond to the situations that havebeen tested and for which the formula is developed). The final choice for a stability
formula is therefore often based on 'engineering judgment' in practice. It should be
noted that with numerical models better quantitative information can be derived
for flow rates and turbulence intensities and thus more certainty can be obtained.
However, this requires a substantial effort.
215

9.3

Taxes

9.3.1

Causes
The soil defense can be charged by various causes, intentionally or unintentionally.
The tax may come from, for example, flow due to:Filling/emptying or draining

Non-closing doors/valves

Overflow

They can also come from ships as a result of(Bow) Screw jetsShip waves and return flow

And they can come from wind waves, where the combination of simultaneous
occurrence of current and waves can be decisive.
For a design verification to the Water Act requirement, only the load due to a highoutside water level and/or high wind waves is important. In the remainder of thissection, therefore, only this tax situation will be discussed.
9.3.2

Types of tax
The stability of the top layer of soil protection is in principle calculated on a load asa result of the following three load cases:
1.

Flow

2.

Wave load, with or without flow

3.

Overflow/splash load

167 頁
1 Load by flow
The load due to currents is often not uniform, but can be better referred to as
radius. Depending on the mechanism, different types of beam forms can occur:Flat rays
The flat beams are created where, for example, doorways do not close (well).
The beam is wide and therefore has a large surface area. This kind of radiation
breaks off relatively easily because the beam makes contact with the216surrounding water over a larger surface area.


Rectangular beams
Rectangular beams occur when leveling locks as a result of the square openings
in the doors. Usually there are several adjacent openings. This allows thebeams to be drawn towards each other and will be less easily broken down by
the lesser presence of surrounding (standing) water.

Round beams
Round beams are generated by (bow) screws and are accompanied by highturbulence intensity. The round beam has the least surface that is adjacent tothe surrounding water and is therefore the least degraded.

The type of jet, and the degree of turbulence ultimately determines to what extent a
certain load can be felt behind the artwork. This is important for the length of thesoil protection. For a design verification to the Water Act requirement, flow due totransfer/overflow and decay flows due to the (unintentionally) opened artwork isimportant. These are generally flat rays.
The load on soil protection by flow can be both pulsating and continuous. A
pulsating load occurs when waves (partly) play a role in the flow over or throughthe artwork. Two load cases can be distinguished here:
A. Waves result in an extra volume of inflowing water with an opened artwork
B. Waves lead (partly) to an overflowing ray behind the closed work of art.
Ad A) In an open work of art, waves usually hardly contribute to the inflowing flow
because the inflowing flow due to the decline over the work of art is dominant.
Nevertheless, situations are conceivable in which waves do contribute to the
inflowing flow. Think of a situation with a relatively small water depth above thethreshold in combination with large waves. In that case the load has a strong
pulsating character.
Ad B) This situation is further elaborated below under 3.
To calculate the flow rate, numerical models can be used. Although often focused
specifically on a type of artwork, there are also available formulas to determine theflow rate. In section 16.4 of the Manual for Designing Granular Soil Defenses [Ref.
9.8] some examples are given.
217

168 頁
2 Load by waves
The soil protection for flood defense structures is usually located below thewaterline and also behind the work of art. As a result, the soil protection is notdirectly attacked by waves. As a result, taxes due to waves play a limited role andare included under 1) and 3).
3 Overflow / splash load
A deviating flow pattern occurs as a result of transhipment and / or overflow over a
closed work of art. In that case the load consists of an overflowing beam over thereversing means / construction of the artwork, which ends up in water of limited
depth. Often this takes place within the contours of the concrete work of theconstruction, after which the overflowing jet spreads over the wet surface of theartwork. At the location of the soil protection, the soil protection is then still taxed
by a flow load.

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）168 頁より作成。
Figure 46 Overflowing beam within contours of concrete work
It is also possible that the overflowing jet directly charges the soil protection.
Consider, for example, transfer and / or overflow over a denomination. This isdiscussed in more detail in section 9.4.2.

218

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）168 頁より作成。
Figure 47 Overflow jet directly on soil protection
Wave transfer by definition leads to a strong pulsating load on the soil protection
behind the artwork. Because no specific relations are known that distinguishbetween pulsating flow and continuous flow, the stability relationships presented in
the next section relate to soil protection structures that are continuously loaded.
9.4

Strength
The strength of the soil protection is determined by the underwater weight of theelements that are used in soil protection. This underwater weight is determined by
the size of the elements (usually expressed as D) and their specific gravity (often
expressed as Δ being the specific gravity of the element minus the specific gravityof the water divided by the specific gravity of the water). (169 頁) Various stability
relationships are available for determining the required combination of specificgravity Δ and element dimension D. In this chapter, the following models are
discussed; all applicable for a situation with flow load:

Shields, extended (applicable for granular soil protection)

Shields for blasting (applicable for granular soil protection)



Pilarczyk (applicable for almost all types of soil protection, see Table 17)219



Escarameia and May (applicable to almost all types of soil protection, see
Table 17)

Although Izbash's formula is also often mentioned, it is not included because thisformula only provides an indication and can be made a better calculation with thehelp of the other theories.
9.4.1

Stability relationships for flow load
The models are presented in the classic way to calculate suitable values for Δ andD at given flow velocities. In this guideline, the use is just the other way around:given a design of a rubble, the critical speed Ucr (sometimes other notation) is
determined which serves as input parameter for the safety verification in thesections Height, Non-closing and Structural failure. The calculation is notprobabilistic; the expected critical speed can be interpreted as a calculation value
because the stability relations presented are usually design formulas in which some
(sometimes hidden) safety is present.
For the type of 'granular soil protection' the aforementioned models can all beapplied. For the other types of soil protection, for the stability relations of Pilarczyk
and Escarameia and May a specific coefficient can be entered that applies to thetype of soil protection. However, no coefficients are available for the asphalt mastic
slabs, stone asphalt slabs and material penetrated with asphalt or colloidal concrete(see also Background report on the track section Height II - Determination ofcritical transfer / overflow flow rate [Ref 9.4]). In those cases where model-based
verification is not possible, physical model tests can be an option.

9.4.1.1

Stability formula of Shields (extended)
The basic relationship for granular material under flow is the relationship of Shields.
The relationship of Shields was originally derived for uniform flow over a horizontal
bed of loose-grained materials. The comprehensive formulation contains correction
factors for slope and non-uniform flow:

170 頁
Here is:220

D

Characteristic element dimension [m]For granular materials: D = D50
D50 = Screen size so that 50% of the weight of a batch can pass stones.

Ucr

Depth-average critical flow rate [m/s]ψcr

Critical shear stress parameter, also called Shield parameter [-]Δ

Relative density [-]Δ = (ρs -ρw)/ρw
ρs = mass density stones [kg/m3]
ρw = mass density water [kg/m3]

C

Chezy coefficient [m0.5/s].
Different formulas are available for this, the most commonly used is C =18 · log (1 + 12 · h/ks) with Nikurad roughness parameter ks = 4 ∙ D50 andh the water depth for soil protection

ksl

Talus factor [-]ψ = angle of the flow with the upward incline direction (°)β = angle of soil protection with horizontal (°)θ = angle of internal friction (°) (for crushed stone 40 °)For flow parallel to the slope (ψ = 90 °):For flow in a downward direction of the slope (ψ = 180 °):kt

Turbulence factor [-]r0 = depth average relative fluctuation intensity due to turbulence [-] In case of
normal turbulence above a flat bed (for example block mat, asphalt mats) r0 = 0,1(10%). In the case of normal turbulence above a rough bed (e.g. waste stone), r0 =0.15 (15%). In case of high turbulence r0 ≈ 0.3 (kt 2 = 2), with extremely highturbulence r0 ≈ 0.45 (kt 2 = 3) applies.

The size of the critical shear stress parameter ψcr depends on the permissible
damage. The table below shows the corresponding behavior for 3 different values.
The value of this shear stress parameter has been derived in the past for sandy
material and uniform flow. Although this value becomes greater with larger stone221

diameters under uniform flow, use should be made of these values below because
other coefficients (such as the relative fluctuation intensity due to turbulence but
also other parameters) are probably calibrated in the different formulas using thesevalues of the shear stress parameter.
Table 18 Values for shear stress parameter ψcr
Shear stress parameter ψcr

Observable behavior

0,03-0,035

Beginning of movement of stones

0,045-0,05

Some transport of stones

0,060

Continuous transport of stones※（Rijkswaterstaat, Central government 2018）170 頁より作成。
For the design of soil protection it is recommended to use the criterion 'start of
movement' and for the assessment the criterion 'some transport of stones'. The
final choice of the value of the shear stress parameter should be based on theaccepted risk of failure of the artwork and the contribution of the soil protection
herein.
171 頁
9.4.1.2. Stability formula of Shields for blasting
The stability formula of Shields can be made applicable for concentrated blasting
above a rock slab covering by using the flow velocity above the soil (Ub), while theinfluence of the turbulence of the beams themselves and of the soil roughness istaken into account in a more direct way. The formula is then:Based on the definition for kt, as given in the extensive Shields formula, it can be
deduced that for Ucr = 1.3 ∙ Ub both formulas yield the same results.
9.4.1.3. Stability formula of Pilarczyk
A widely used formula for calculating soil protection is the Pilarczyk formula. The
advantage of this formula is that the different influencing factors are described
separately. This allows the formula to be tailored to specific situations. Essential
here is a correct estimate for the different parameters. However, as the application
becomes more specific, less information about these parameters is known and the222uncertainty about the estimate increases. The spread around the different
parameters is decisive for the spread around the calculated stone diameter. The
Pilarczyk formula reads:

Here is:D

Characteristic element dimension [m]For granular materials: D = Dn50
Dn50 = nominal stone diameter of a stone piece with a mass M50.
Dn50 = (M50/ρs) 1/3.
M50 = mass [kg] of a stone from the stone grading for which 50% of themass of the stone grading consists of bricks that are lighter than
this mass.
ρs = mass density stones [kg/m3]
For gabions and stone mattresses: D = thickness element
D = block thickness applies to block slabs.

φscStability parameter to take into account the influence of transitions andthe deviating hydraulic loads that occur here. For φsc the following values
are used:

Termination of directly infused gabions/stone mattresses: φsc = 1.0

Termination of directly poured loose rubble stone: φsc = 1.5



Rubble stone in a continuous layer (minimum two layers of stones):
φsc = 0.75



Stone settlements, continuous (brick or block) mat constructions: φsc
=

Δ

0.50

Relative density [-]Granular materials, stone settlements, block slabs: Δ = (ρs - ρw) ρw
Gabions, stone mattresses: Δ = (1-n) · (ρs - ρw)/ρw
ρs = mass density stones [kg/m3]
ρw = bulk density water [kg/m3]

172 頁
n = open space content (including pores) [-]; for gabions and mattressesn ≈ 0.4
ψcr

Shear stress parameter [-]223

Compares the stability of the system with the critical shear parameter ofloose stones according to Shields, for which a value of 0.035 is used for the
Shields parameter.
ψcr = 0.035 for granular materials
ψcr = 0.070 for gabions, stone mattresseskhDepth parameter [-]kh = 2 / (log2 (1 + 12h / kr)) for fully developed speed profilekh = (1 + h / D) -0.2 for not fully developed speed profileh = water depth [m]kr = Dn for hydraulically smooth elements, concrete blocks
kr = 2 ∙ Dn for rough elements, such as quarry stone
The factor Kh can be neglected if instead of the average flow rate with thelocal velocity near the soil is counted.

ksl

Talus factor [-]ψ = angle of the flow with the upward incline direction (°)β = angle of soil protection with horizontal (°)θ = angle of internal friction (°) (for crushed stone 40 °)For flow parallel to the slope (ψ = 90 °):For flow in a downward direction of the slope (ψ = 180 °):kt

Turbulence factor [-]kt 2 = 0.67 in case of low turbulence and uniform flow
kt 2 = 1.0 at normal turbulence (e.g. flow in rivers)
kt 2 = 1.5 with increased turbulence (common, non-uniform flow)
kt 2 = 2.0 at high turbulence (downstream of a water jump or in a sharp
bend)
kt 2 = 3 at very high turbulence (for example jet, screw jet load or nearwater jump)

U0

Depth-average flow rate [m / s]gGravitational acceleration (g = 9.81 m / s²)

For the stability parameter φsc to be used, it is important to know whether edges are
directly supplied or not. This refers to a situation as shown in Fig. 48, situation a,with the direction of flow in the direction of the overlap. For edges where the flow
travels in the same direction as the overlap, the stability parameter for a continuous
224

layer / mat construction can be used (see also situation b in figure 48).
173 頁※（Rijkswaterstaat, Central government 2018）173 頁より作成。
Figure 48 Examples of direct and non-direct edges
9.4.1.4. Stability formula of Escarameia and May
With the formula of Escarameia and May can be designed in addition to bricks forstone settlements and stone mattresses / gabions. The formula of Escarameia and
May is as follows (River and channel revetments - A design manual [Ref 9.11]):

Here is:Dn50

Dn50 = nominal stone diameter of a stone piece with a mass M50.
Dn50 = (M50 /ρs) 1/3.
M50 = mass [kg] of a stone from the stone grading for which 50% of themass of the stone grading consists of bricks that are lighter than
this mass.
ρs = mass density stones [kg/m3]
For gabions and stone mattresses the Dn50 applies to the stones in the225gabion/ stone mattress
For blocking, Dn50 = block thickness applies
Kt

Turbulence coefficient [-] For this applies:
Stone: Kt = 12,3 ∙ ru, b - 0.20 *Gabions and stone mattresses: Kt = 12.3 ∙ ru, b - 1.65 **Stone settlements: Kt = 0,75 ∙ (12,3 ∙ ru, b - 0,20) = 9,22 ∙ ru, b - 0,15 ***Block mats: Kt = 0.05 ****([Escarameia, 1995]) Kt = 1.79 ∙ ru, b - 0.72 ****** Valid as ru, b> 0.05 and slope slope 1: 2 or faint** Valid as ru, b> 0,12 and slope slope 1: 2 or faint*** Valid as ru, b> 0.05 and slope slope 1: 2.5 or faint(174 頁)**** Valid as ru, b <0.43 and slope slope unknown***** Valid as 0,43 <ru, b <0,90 and slope slope unknown
ru, b = turbulence intensity at 10% of the water depth above the soil
protection [-]Normal turbulence: ru, b = 0.12
Increased turbulence: ru, b = 0.20
Moderate to high turbulence: ru, b = 0.35 to 0.50
Very high turbulence: ru, b = 0.60
Ub

Flow rate at 10% of the water depth above the soil protection [m/s]Ub = (-1.48 · ru, b + 1.04) · U Valid if ru, b £ 0.5
Ub = (-1.48 · ru, b + 1.36) · U Valid if ru, b £ 0.5
U = average flow rate [m/s]Δ

Relative density [-]For this applies: Δ = (ρs - ρw)/ρw
ρs = mass density stones [kg/m3]
ρw = bulk density water [kg/m3]

gGravitational acceleration (g = 9.81 m / s²)

The Escarameia and May formula implicitly includes a safety factor because it isintended for designs. It is not known how great this safety factor is. Furthermore,
the water depth is not included in the formula of Escarameia and May, which leads
to larger elemental dimensions compared to Shields and Pilarczyk, particularly indeeper waters.

226

9.4.2

Stability calculation for overflow/splash load
Almost no literature is available for overflow/splash load. In Background report test
track Height II - Determination of critical transfer/overflow flow rate [Ref. 9.4] themodel of Free castle is cited. Although in [Ref. 9.4] it is concluded that thereliability of this model is not so great, it can be used to obtain a first indication.
Use can also be made of the guide values as included in table 7-4 of theschematization manual for the height of the artwork [Ref. 5.4].
Depending on the contribution of soil protection to the total risk of failure,consideration can be given to physical model research.

※（Rijkswaterstaat, Central government 2018）174 頁より作成。
Figure 49 2D Physical model research soil protection (source: Deltares)
175 頁
9.5

Other verifications

9.5.1

GeneralIn general, the verifications in this section do not apply to the draft verification to
the Water Act requirement because the dimensions of the soil protection areusually not determined by the flood water situation but by other load situations.
However, it is possible that the high water load situation is decisive for thedimensions of soil protection. That is why this section briefly discusses otheraspects than the dimensions of the top layer.

9.5.2

Horizontal dimensions
The required length of the soil protection is determined by analyzing thegeotechnical stability when a drainage pit develops downstream of the protection as227

a result of erosion. When the depth of the pit is large or the setting of the pit
becomes very steep, shearing or settlement flow can take place. Landing flow is asoil mechanical instability in which a originally loosely packed granular soil mass
becomes softened and flows out due to the slope present. The density and thepermeability of the soil package are of great influence.
Shear is a soil mechanical instability in which no softening occurs, but the soil mass
as a whole undergoes a downward displacement. Depending on the storage length,a shear or a settlement flow can threaten the stability of the artwork. The chance ofinstability therefore becomes smaller with increasing length of soil protection. The
flow velocity also decreases at the edge with increasing length. In addition to theextension of the soil protection, it is also possible to opt for defending the supply
slope by recording it. This can be realized, for example, as 'falling apron'.
The minimum length of the soil protection is therefore dependent on the pit depth
and steepness of the pit. In addition, the type of soil material is of influence. If
settlement flow is possible, the gradient of the end profile will be very faint, forexample 1:15, while with shear this gradient will be 1: 6 to 1: 8.
This section describes a method for assessing the length of the soil defense. Thismethod is based on a salvage model, in which the two situations, immediately
before and after geotechnical instability, are compared with each other. In the
Scour Manual ([Ref 9.5]) the salvage model is described and various mean andmaximum values are given that can be used for a general design relationship in
which the length of the bottom defense is derived.
The collapse of soil protection as a result of geotechnical macro-instability is
initiated by the formation of excavations at the edge of soil protection. If here too
steep slopes in combination with too deep pits occur, settlement flow or shear canoccur depending on the base.

228

176 頁※（Rijkswaterstaat, Central government 2018）176 頁より作成。
Figure 50 Storage model (2D) for shear and settlement flow.

Where O1 = O2 applies
Here is:
Ls

Entry length [m]ydErosion depth at the transition from the steepest slope to the second slope[m]ym

Maximum erosion depth [m]βaAverage slope for instability [m]γ1Slope steepest slope after instability [m]γ2Slope angle second slope after instability [m]O1

Slid surface [m2]O2

Deposited surface [m2]The storage length must be less than the length of the soil protection applied. Whenyd is set equal to 0, the acceptance length is the greatest.
The acceptance length depends on the maximum erosion depth. The erosion depth
development is a time-dependent process. Reference is made to the Scour Manual,
Chapter 3 ([Ref.1.5]) for the calculation method.
The equilibrium depth achieved after a long time load can be estimated with thefollowing formula (Scour Manual [Ref 9.5]):229

If the average flow velocity U0 is a number of times greater than the critical flow
velocity Ucr then the formula yields unrealistic values. Limitation of the equilibrium
depth to twice the water depth can then be used. The size of Ucr depends on thesurface. In the Scour Manual ([Ref 9.5]) a relationship is given to calculate this value
as clay particles and thus cohesion must be included. For granular materials thepreviously given formulas can be used. (177 頁) In addition to the length, the width isalso important. CUR 197 Quarry Stone in Practice [Ref. 9.2] gives a first impulse forthis when the current starts to widen, as with a diver. The total required width (B) is
determined here on the basis of the assumption that the flow spreads at an angle of 1:
6. B can then be calculated on the basis of the length, so B = 1/3 · L + bu.

※（Rijkswaterstaat, Central government 2018）177 頁より作成。
Figure 51 Determination of width of soil protection on the basis of spreading angle (source:
CUR 197)
9.5.3

Vertical structure
The material that forms the top layer of soil protection is usually too large to lay
down directly on the existing soil. Often one or more filter layers are applied, which
together have the function of preventing erosion of the soil and thus forming ageometrically dense structure. A geometrically dense structure can also be realizedby placing a geotextile directly on the bottom material and thereby saving one ormore filter layers. To meet geometric-tight filter layers, there are requirements for
specific maximum ratios between the layers. These requirements relate to surface
stability, internal stability and water permeability. For the formulation of the230requirements reference is made to the Handbook Design of lock locks ([Ref 9.8]),
section 16.7.3.
There are also geometrically open filters. The top layer should then have asufficient thickness such that the hydraulic gradient becomes too small to set thesoil material in motion. However, existing calculation rules are currently based on
more or less uniform flow. The effect of turbulence on the minimum thickness ofthe top layer is not known. Physical model research must first be done for this. The
costs of model research usually far outweigh the costs of an extra filter layer andthus a geometrically open filter can be economically a good alternative forgeometrically tight filters. Additional information on geometric-open filters isavailable in CUR 161 Filters in hydraulic engineering [Ref. 9.1], CUR 233
Interface stability or granular filter structures [Ref. 9.2], Validation andoptimization of a design formula for geometrically open filter structures [Ref. 9.9]
and Granular open filters on a horizontal bed under wave and current loading [Ref.
9.10].
Both the top layer and the filter layers must have a minimum thickness. For theminimum thickness, a distinction is made between fine grading and light grading.
In addition, a distinction is made in the method of application, namely from land in
the dry, from land in the wet and from water by dumping. For geometrically dense
filters, a fixed surcharge on top of the 2xDn50 layer thickness is used for fine grading(Table 19). (178 頁) For light grades, the supplement is equal to 0.5 to 1xDn50 of
the grading (Table 20). The tables below show the tolerance and average thickness
for geometric-tight filters for fine grading and light grading. The minimum
thickness is set equal to 2xDn50.
Table 19 Tolerance and average thickness in geometrically tight filters fine grading
Tolerance

Average thickness

Fine grading

Dn50*

Df = 2.0 Dn50 + tolerance
dry

wet

depositDf_droog

Df_natDf_storten

[m]

[m]

[m]

[m]

[m]

[m]

[m]

oud: 40/100 mm

0.063

0.1

0.15

0.2

0.23

0.28

0.33

oud: 80/200 mm

0.127

0.1

0.15

0.2

0.35

0.40

0.45

45/125 mm

0.067

0.1

0.15

0.2

0.23

0.28

0.33

63/180 mm

0.097

0.1

0.15

0.2

0.29

0.34

0.39

231

90/250 mm

0.135

0.1

0.15

0.2

0.37

0.42

0.47

45/180 mm

0.080

0.1

0.15

0.2

0.26

0.31

0.36

90/180 mm

0.114

0.1

0.15

0.2

0.33

0.38

0.43

※（Rijkswaterstaat, Central government 2018）178 頁より作成。
* Average Dn50 at a density of 2650 kg/m3
Table 20 Tolerance and average thickness for geometrically tight filters for light sorting

Light Sorting

Dn50*

Accuracy

Average thickness

f x Dn50

Df = 2,0 Dn50 + accuracy

fdroogfnat

fstorten

Dfdroog

Dfnat

Dfstorten

[m]

[-]

[-]

[-]

[m]

[m]

[m]

5-40 kg

0.20

0.5

0.8

1.0

0.50

0.56

0.60

10-60 kg

0.24

0.5

0.8

1.0

0.60

0.68

0.72

40-200 kg

0.36

0.5

0.8

1.0

0.91

1.02

1.09

60-300 kg

0.42

0.5

0.7

0.9

1.04

1.13

1.21

15-300 kg

0.38

0.5

0.7

0.9

0.94

1.02

1.09

※（Rijkswaterstaat, Central government 2018）178 頁より作成。
* Average Dn50 at a density of 2650 kg/m3
9.5.4

Flexibility
Wherever the soil protection ends, erosion occurs. The edge of the soil protection
must be so flexible that it can follow the excavations without major problems. The
connection of the soil protection against a hard construction must be carefully
carried out in order to prevent possible erosion of the base material. An example isgiven in Figure 52.

232

179 頁※（Rijkswaterstaat, Central government 2018）179 頁より作成。
Figure 52 Detail of soil protection connection to a vertical construction
9.6

Dealing with empirical formulations and uncertainties
Stability relationships are available for the various tax types, each valid for a limited
scope and each with uncertainties due to uncertainties in the input parameters anduncertainties in the quality of the derived stability relationships. These
formulations can serve as a starting point for the conceptual design of soil
protection. Due to the limited validity and accuracy, physical model research can beconsidered. This is partly dependent on the contribution of soil protection to thetotal risk of failure.

9.7

References and background documents[Ref. 9.1]

CUR publication 161, 1993, Filters in hydraulic engineering,
Gouda.

[Ref. 9.2]

CUR-publication 197, 2000. Quarry stone in practice, Part 2:
dimensioning of constructions in inland waters. CUR
Foundation, Gouda.

[Ref. 9.3]

CUR-publication 233, 2010, Interface stability of granular filter233structures, Theoretical design methods for currents, CURNET,
Gouda.
[Ref. 9.4]

Deltares, 2015. WTI 2017 Works of art, Background report of
the test track Height II - Determination of critical transfer /overflow flow. Report 1220087-001-GEO-0011-jvm.

[Ref. 9.5]

Hoffmans, G.J.C.M. and H.J.Verheij, 1997. Scour Manual. A.A.
Balkema, Rotterdam.

[Ref. 9.6]

Hoffmans, G.C.M., 2012. The Influence of Turbulence on Soil
Erosion. Deltares Select Series Volume 10, Eburon.

[Ref. 9.7]

Rijkswaterstaat (Directorate-General for Public Works andWater Management) Construction service, 1995. Guide to
Designing Granular Soil Defenses behind Two-Dimensional
Outlet Constructions

180 頁[Ref. 9.8]

Rijkswaterstaat (Directorate-General for Public Works andWater Management) Bouwdienst, 2000. Design of Schutsluizen,
Part 2. Ministry of Transport, Public Works and Water
Management, Directorate General of Public Works and Water
Management.

[Ref. 9.9]

Van de Sande, S.A.H., Uijttewaal, W.S.J., Verheij, H.J., 2014.
Validation and optimization of a design formula for geometrically
open filter structures, Proc. 34th International Conference on
Coastal Engineering (ICCE), Seoul, Korea.

[Ref. 9.10]

Wolters, G. and Van Gent, M.R.A., 2012. Granular open filters
on a horizontal bed under wave and current loading, Proc. 33rd
International Conference on Coastal Engineering (ICCE),
Santander, Spain.

[Ref. 9.11]

M. Escarameia, River and channel revetments - A design manual,
1998

234

181 頁

10

Cup storage

10.1

Introduction
The size of the cup storage is directly important in determining the failure
probabilities of the artworks. The definition of the combining capacity is alreadyset out in section 2.2. This chapter discusses the various aspects of cup storage.

10.2

Size of available cup storage (Vc)
The size of the available storage space depends on various aspects that are
discussed in this section. In its most basic form, the combining capacity is nothing
more than the permissible water level increase multiplied by the surface of thestorage area. In formula form this is as follows:

In which:
Vc

Maximum available volume of storage capacity in the hinterland with nosubstantial consequences [m³]10.2.1Akom

The available surface in which water can be recovered [m²]△hkom

Permissible water level rise in the combing area [m]Permissible water level rise in the catchment area (△hkom)
The permissible water level increase in the flood risk approach is related to theeffects that occur in the hinterland. This water level rise in a (water) system behinda work of art concerns the difference between the inner-dike level at the beginningof the high-water situation and the inner-dike level where there are no substantial
consequences and / or victims. This last level is also referred to as open turning
height (OKH).
Open Reverse Height (OKH)
The OKH concerns the maximum permissible inland water level where there isjust no failure of the inner dike water barrier. The Open Turn Height is always
related to the properties of the area or the structure (s) on the inside of the flood
defense. This level, together with the other characteristics of the underlying(water) system (surface area, inland water level, etc.), is responsible for the size235

of the storage capacity. It forms part of the 'strength' of the work of art withregard to not closing.
When determining the water level at the beginning of the high water situation,account must be taken of what precedes a high water situation. In many cases, thisinitial level will be higher than the average level or the target level as a result of, forexample, precipitation before and during the high water period. But also the policyof the flood defense manager in an approaching high tide is of influence. In
connection with, for example, seepage, an administrator can decide to set up theinside water. On the other hand, he can also decide to just grind down an inland
waterway, so that additional cup storage is available.
This additional cup storage is then mainly intended to be able to recover from thehinterland during a high water period. (182) The maximum permissible indoor
level is primarily related to damage and / or casualties. For underlying barriers thestarting point can be that for as long as the water level is lower than the test waterlevel associated with the standardization of these (regional) flood defenses, they
will not fail. This means that it is explicitly assumed that the underlying flood
defenses are in order and meet the requirements that apply to them. This alsomeans that the maximum permissible level may be lower than the deflecting heightof the rear defenses, because these fail, for example, as a result of piping or stability
at lower water levels than the deflecting height.
Other criteria may also be linked to the maximum permissible internal level. An
example of this is salty, when too much salt water leads to substantial damage tonature or agriculture.
There is a different situation for denominations. There is no underlying water
passage in which water can be salvaged immediately. In the case of failure of adenomination, water flows directly over the ground level of the hinterland. If thisconsists of grassland, the consequences can still be limited. If the denomination is
located in a residential core, inflow of water will immediately lead to nuisance. Inthat case direct use can be made of the term 'substantial economic damage' as
defined in section 2.2. It is recommended to take account of cup storage as much as
possible for denominations in urban areas (residential areas) and to comply withthe requirements by means of the retaining capacity of the denomination.
236

10.2.2

Surface area storage area (Akom)
Determining the storage surface can be done from very coarse to very accurate.
This depends in particular on the specific situation. In the figure below, a fictitious
situation is outlined on the left, involving a complex system of water surfaces. In
addition, the cross section of the waterways is not constant and runs with the waterlevel. Also a low-lying pasture present, of which the flooding is very limited has
consequences.

183 頁※（Rijkswaterstaat, Central government 2018）183 頁より作成。
Figure 53 Compressed area complex (left) and simple (right)
In the left situation above, there is no single storage surface. It is clear that one
immediately has to think of accumulating volume (s).

237The situation can also be fairly simple (see figure 53, right); for example, when thewaterway behind the artwork is a channel with clear quays and an unambiguous
transverse profile.
Tools that can be used in determining the storage surface are GIS applications andcalculation software for model calculations.
It is advisable to determine the surface of the area in the first place(conservatively). A lot of uncertainties play a role as far as the combining capacity
is concerned, but also with regard to the inflowing volume when the artwork fails.
The accurate determination of the storage surface (capacity) is therefore only
useful if the other aspects are also taken into account in an accurate manner.
Certainly for the design of a work of art, an overall, somewhat conservative way ofdetermining the storage capacity is recommended in the context of a robust design.
10.2.3

Other influencing factors of storage capacity
In addition to the surface area and the critical level increase, there are a number ofother factors that influence the available storage space for failure, such as: (184 頁)
Rain in the underlying system or the influx of rivers and canals.



Pumps and pumping stations that are used during high water to curb theindoor level have a positive effect on the storage capacity.



Pumps and pumping stations that are used to discharge water from the polders
onto the waterway (s) have a negative influence on the storage capacity.

10.2.4

Distribution of storage capacity over several works of art
When the combative capacity is known, it should be considered which part of thisis available for the artwork to be designed. To this end, a list is drawn up of works
of art that use the same cup storage. These works of art can be located in the samedike section, but can also belong to another dike section and even to another dikering.
A first conservative approach could be to distribute the available storage space
proportionally over the present and the artwork to be designed (Vc/n). A sharper
division can be made by looking at the failure mechanisms of the various artworks
and determining to what extent these are independent or dependent. When theoutside water level is strongly dominant for the failure probabilities of the artworks,
238there is a considerable dependency and when the failure probabilities of thestructures are the same, the distribution is proportional to the cup storage.
To make a more accurate distribution, a (probabilistic) analysis of the artworks
involved is therefore necessary. It is then important to analyze the chances thatwhen the artwork to be designed fails, another work of art also fails. If thepreconditions and structure of two works of art are completely identical, it is clearthat this opportunity is high. In that case, a part of the cup storage can be allocatedto each work of art. If, however, the works of art have very different failure
probabilities and the circumstances in which failure occurs are not comparable, thisis too conservative and the room storage can be fully attributed to the artwork to be
designed. All this can take the necessary effort. Using the conservative approach istherefore recommended in the first instance.
A specific point of attention concerns the transhipment/overflow at the dikes. For
dykes, there are no guidelines and/or recommendations regarding storage.
However, it is clear that with larger overflow/transhipment rates of dykes (not yet abreach), the capacity of the area to absorb is also called for. When designing a newwork of art, it is therefore recommended to pay some attention to this. This isparticularly the case with high outside water levels where water flows over the
artwork and possibly over the adjacent dike sections.
10.3

Inflowing volume
When the water retaining capacity of the artwork has reached its limit and there is
therefore an appeal to the storage capacity, it depends on a number of things how
quickly (flow) and how much (volume) outside water flows in through/over the
artwork.
A. The failure mechanism that occurs
B. Dimensions of the water-carrying element (s)C. Occurrence of breaches
D. The moment of failure in time

185 頁
E. The course of the flood wave over time
F. The course of the inland water level in time239

In addition, the course of the floodwaters and the inland water level plays a role in
the inflowing flow. The various aspects are discussed in more detail in thefollowing paragraphs.
10.3.1

Emerging failure mechanism
Depending on the occurring failure mechanism, a certain influx situation arises forthe artwork. For example, the inflow opening is different in the event of failure of
the closure than in the case of overflow/transfer. The way in which water flows in isalready described in the various failure mechanisms.
Height. For height applies that inflow occurs over the reversal / artwork,where there is no direct contact between inside and outside water levelDo not close. In the case of non-closing, inflow occurs in the first instance by
the water-carrying elements present. This can be through a tubular crosssection (for example, inlet diver), but also an open box construction such as afloodgate.

Piping. With piping, the basic principle is that when a breach occurs, a breachis created in the flood defense. With this failure mechanism, no account istaken of cup storage.

Strength and stability. For this failure mechanism, it is generally true that an
uncontrollable situation will occur in the event of failure, while cup storage
hardly affects the failure probability. Failure always takes place at high outside
water levels, so that the flow rates of the inflowing water quickly lead tofurther breach formation. In the failure mechanism strength and stability,
therefore, no account is taken of cup storage in designs

10.3.2Dimensions of water-carrying element (s)After a failure mechanism occurs, the size of the inflowing flow rate is determinedby the physical dimensions of the water-carrying elements. For example, the totaltranshipment over a narrow denomination is smaller than over a broad
denomination. With a broad denomination, the maximum admissible inflow
volume will thus have been reached earlier. The physical dimensions of the watercarrying elements are always determined by the primary function of the artwork.
The flood defense function has no direct influence on this.

10.3.3Occurrence of breachingIf after the occurrence of a certain failure mechanism there is a rapid question of240

further breach formation and breach growth, the inflowing flow is difficult todetermine. For those situations, the design of a work of art is recommended toassume that the occurrence of the failure mechanism directly leads to the failure of
the artwork (occurrence of flood effects). In particular for strength and stability
and piping this is a recommended starting point because these usually take place athigh outside water levels and, upon collapse, an uncontrollable situation
immediately arises. Possible exceptions to this are inlet/outlet divers and pressure
pipes from pumping stations.
186 頁
10.3.4Course of the flood water and the inland water level

The maximum permissible outside water level in the event of the occurrence of a
failure mechanism depends on the course of the high water wave, the occurring
waves, the method of inflow and the inland water level. This outside water level isreferred to as the open timespan (OKP) 37 in the Guidelines for Art Works 2003
(Ref No. 10.2). However, since this outside water level depends on a number of
uncertain parameters, such as the course of the flood wave, there is not one OKP,
but there are many OKPs. In addition, in the Guidelines for Art Works 2003 [Ref.
10.2] do not close the OKP mainly related to the failure mechanism. Based on theabove, the term OKP is no longer used in this manual.
As a result of inflowing water, the inland water level also increases during a highwater wave. The extent to which depends on the size and configuration of the cup
storage. In a very large bowl the inland water level is hardly influenced, while in avery small basin the inland water level will run along with the outside water level.
This means that the inflowing flow varies during a high water wave.
In the chapter Hydraulic Loads (see chapter 3) the gradients of a high water are
indicated for the different water systems. These are based on the Water Level
Course tool. This contains one form of the flood water per system / area, which isstill considered as decisive for the time being. The relevant chapter also indicates
how to deal with waves during a flood wave38.
10.4

Practical approach to inflow volume
In the chapter height (see chapter 5) it is indicated how storage and transfer /overflow can be included in the design for this failure mechanism. For non-closing,241the method below indicates how it can be verified whether the available cup storageis adequate for a specific situation. More specifically, which outside water level
does not lead to the occurrence of flood effects in the hinterland when the closure
fails. For piping and strength and stability, when designing a new work of art, it isrecommended not to take account of cup storage. If this is chosen for a specificreason, most of the following steps (see Figure 54) can also be run through.
____________________________________
37

Open Turning Level (OKP): Outdoor water level which, when the valve is open, does notexactly lead to an inadmissible inflowing volume of outside water ([Ref. 5.5])
38

Within the WBI, the high-water wave is schematized as a block that is initially calculatedwith a duration of 6 hours. It has been found that this may be suitable for wind-dominatedload systems with a wave height up to approximately 2 m, but certainly not for draindominated load systems. In the latter case, it is recommended to use the water level gradientfrom the Water level gradient tool to arrive at an adequate estimate of the inflowing volume.
____________________________________

242

187 頁
Step 1
Determine the winding volume available for the artwork on
the basis of the storage surface and the OKH.

Step 2
Determine indoor water level at the beginning of the flood
wave.

Step 3
Determine the inflow model (for example 'drowned tube').
For the model vertical wall / high reference is made to theworking method at height (chapter 5)

Stap 4
Estimate a value for the maximum permissible outside waterlevel where the accumulating volume is not exceeded during
a high water wave

Voptredend ≠Vc

Stap 5Determine the course of the high water wave using theWater Level Course tool, based on the outside water level
determined in step 4.

Step 6
Calculate on the basis of the currently available data whether the

inflowing flow rate during the high tide wave (Voptredend) is equal,
smaller or greater than the available storage space (Vc)

Voptredend = Vc

Ready※（Rijkswaterstaat, Central government 2018）187 頁より作成。
243

Figure 54 Step-by-step approach to combing capacity with reliability of closure
If at step 6 the inflow volume is greater than the available storage space, step 4 canbe filled in again by maintaining a lower maximum permissible outside water level.
In case the inflow volume is smaller than the available volume, a higher outside
water level can of course be maintained at step 4. It may therefore be necessary to
make several iteration strokes before finding the desired maximum permissible
outside water level.
When there is a (very) small storage room with some simple hands can be viewed
whether the entire step plan must be completed. The probability is then that theinland water level can immediately follow the outside water level, so that it isimmediately clear which maximum outside water level is permissible from the pointof storage. (188 頁) Of course, it remains to be seen whether the soil protection iscapable of withstanding the flow velocities of the inflowing flow.
10.5

ExampleIn this section an example is worked out for the situation of a drainage diver. It isdetermined which open water level is maximally permissible (peak value of the highwater wave) in case the closure of the diver fails. Three approaches are given for
this.

10.5.1Data
The following information is available:


Immersion model: drowned tube

Inland water level at closure: NAP +0.0 m

Permissible rise in water level in the water level = 1.25 m (= NAP + 1.25 m)



Surface area storage: 400,000 m2



Storage volume: Vc = △hkom · Akom = 1.25 m · 400,000 m² = 500,000 m³



Course of flood water: See figure below. The peak period lasts 2 hours with apeak water level Hpiek.



Closing level: NAP +0.0 m.

Surface diver: 1.0 m2

No inflow of water from the hinterland and no use of pumping stations.



Waves do not play a role because inflow occurs via a tube.

244

※（Rijkswaterstaat, Central government 2018）188 頁より作成。
Figure 55 Course in the time of the external water level during a flood wave
10.5.2First approach
The first approach concerns a conservative approach, in which the drain wave isschematized as a block with a duration of 40 hours and a constant water level Hpiek.
In the first instance, a peak water level of NAP + 2.0 m is maintained. This leads tothe following figures concerning the course of water levels and inflow.

189 頁※（Rijkswaterstaat, Central government 2018）189 頁より作成。
245

Figure 56 Gradation in time of the water levels during high water wave with first simple
approach
The red dotted line concerns the precondition that the inland water level may notexceed NAP + 1.25 m. This is exceeded and thus a peak water level of NAP + 2.0
m outside water level is too much for the cup storage. This is also clear in the figure
below, in which inflowing flow and volume are displayed.

※（Rijkswaterstaat, Central government 2018）189 頁より作成。
Figure 57 Gradation in time of flow and volume during high water wave at first simple
approach
190 頁
It is visible that the total inflow volume exceeds the critical volume of 5,0·105 m³.
The calculation of the inflow volume has taken into account the increase in theinland water level.
By performing a number of iterations it is finally found that at a maximum outside
water level of NAP +1.4 m (H peak) the accumulating volume is not exceeded.
10.5.3

Second approach
The second approach concerns an approach in which the duration of the high246

water wave is reduced so that it can again be calculated with a block shape, butwhere the area under this block shape is equal to the surface under the trapezoidal
shape of the actual discharge wave (see orange line in the figure below).

※（Rijkswaterstaat, Central government 2018）190 頁より作成。
Figure 58 Schematic course over time of the outside water level for the second approach
So now the duration of the high water wave of 21 hours is calculated. When this isworked out and a number of iterations are carried out, a maximum allowable
outside water level of NAP + 2.90 m is found. The graphs below show the course of
the water level and the inflow volume.

247

191 頁※（Rijkswaterstaat, Central government 2018）191 頁より作成。
Figure 59 Gradation in time of the water levels during high tidal wave in the second
approach※（Rijkswaterstaat, Central government 2018）191 頁より作成。
Figure 60 Gradation in time of flow and volume during high water wave at second approach248

10.5.4

Final approach
In the latter approach, the course of the high water wave, as given, is also used in
the calculations. If the criteria of a maximum increase of the indoor level to NAP +1.25 m and 500,000 m3 are again maintained, a maximum outdoor water level of
NAP +2.82 m is found. The diagram below shows the course of water levels andflow rates.

192 頁※（Rijkswaterstaat, Central government 2018）192 頁より作成。
Figure 61 Course in time of the water levels during high water wave in the last approach249

※（Rijkswaterstaat, Central government 2018）192 頁より作成。
Figure 62 Flow in time of flow and volume during high water wave at last approach
10.5.5Conclusion
The first rough approach leads to a permissible outside water level of NAP + 1.40
m. The second and third approaches do not differ much from each other. It is clearthat the permissible outside water level can be considerably larger in a moreaccurate calculation. For non-closing, this can make a lot of difference, because theexceedance frequency of the maximum permissible outside water level plays animportant role in this failure mechanism. The difference between the whole roughapproach and the accurate calculations is about 1.4 m. With a decimation height of
0.5 m, for example, it saves approximately 3 (factor 1000) on the failure
probability.

193 頁
10.6

References and background documents[Ref. 10.1]

Foundations for flood protection, Expertise Network Flood risk
management, ISBN / EAN: 978-90-8902-151-9, second revised
edition, November 2017

[Ref. 10.2]

Guide to Works of Art 2003, TAW, May 2003250

195 頁

11

Case

11.1

Introduction
This chapter contains an example of the application of the Work Guide for theverification of the design of an artwork to the Water Act and the Building Decree.
The example concerns a lock in an existing spatial situation.

11.1.1

Purpose of this chapter
This chapter provides insight into the application of the Work Guide, in which thepractical application becomes immediately clear. The aim is to provide insight into
the possibilities of using the Work Guide and the role it can play in designing awork of art and the relationship with aspects such as maintenance, management
and operation of the object.

11.1.2Depth of this chapter
This chapter discusses all relevant failure mechanisms that apply to a flood defense
artwork. This involves the derivation of the requirements and the way in whichthese requirements can be converted into a design or taxes for the design. With thehelp of taxes (specialists) specialists can further develop the design for water
defenses, such as determining the provisions for piping or the dimensions of thestructural elements of retention devices.

11.2

Description of the situation and the preliminary design

11.2.1

GeneralDue to the large growth of water sports in the region, it was decided to build anextra waterway between the Black Water and the water sport areas behind it. Thisis planned in Zwartsluis, where a lock is constructed between the Black Water andthe Whaa. From the primary function - passing shipping - a preliminary design wasmade for the lock. The preliminary design is verified in this case against therequirements of the Water Act and the Building Decree.
This is a fictitious case, because the existing lock the Whaa is already present at thesite of the intended object. The case therefore assumes that it does not yet exist.
Since the surge barrier is constructed to enable the passage of ships, the width of251the passage opening is already known from this function. The length of the artworkis also a given and is geared to the choice of the turning means (point doors) andthe width of the connecting dike bodies.
11.2.2

Location
The object is located in the municipality of Zwartsluis and concerns a work of art in
the dike section 9-2 (dike ring 9, Vollenhove. The outside water is the Black Waterand on the inside there is a small bowl called the Whaa. The connection of thisbowl with the underlying waterways is regulated via the Aremberger lock.
Originally this lock was located in the primary flood defense, but in the year 2000 a
new primary barrier was installed on the outside.

196 頁※（Rijkswaterstaat, Central government 2018）196 頁より作成。
Figure 63 Overview of the site lock the Whaa (Source: Google Maps)
The old defense has a vertical height that is at least equal to NAP +2.50 m. The
Whaa bowl has an area of approximately 8,750 m². When the level of the Whaa
rises above the NAP +0.50 m, the bowl is outside its normal banks. At a water levelof approximately NAP +1.0 m, there is substantial flooding between the old andnew flood defense systems and an area of around 25,000 m² is under water.

252

Behind the Aremberger Lock is the Aremberger Canal, which is in open
communication with various large water sport areas, such as the Beulakerwijde,
Belterwijde, and the Boschwijde.
197 頁※（Rijkswaterstaat, Central government 2018）197 頁より作成。
Figure 64 Details location lock the Whaa (Source: Google Maps)
The storage area of the rear area is large and is estimated at 2.0 · 107m². The level
rise that can take place here without major consequences is estimated at 0.5 m.
Here, the daily level of the rear area is approximately NAP -0.80 m.
11.2.3

Dyke track data
The lock is located in dike section 9-2. The following information applies here:Standard according to signaling value: 1 / 3,000 per yearStandard in accordance with lower limit value: 1 / 1,000 per yearArtworks in the dyke route: see figure below

253

※（Rijkswaterstaat, Central government 2018）197 頁より作成。
Figure 65 Artworks in dyke route 9-2 (background Google Maps)
198 頁
Of the existing five structures in the dyke section, the following is known globally:
1. Gemaal Kadoelen (a polder pumping station in Amsterdam-Noord: Closing isprovided by two independent reversing devices which automatically close when
the pump is turned off and automatically open when the pump is switched on.
The hinterland consists of pasture.
2. Gemaal Barsbeker (pumping station): This concerns a mortar pumping station
with a non-return valve on the outside and an emergency slide in the pumping
station that closes automatically in case of high water. This slide can also be
operated manually. The lifting point of the auger can be adjusted manually (forexample in the case of higher outside water). The pressure cooker of the auger
pumping station has dimensions of H × B = 1.25 × 1.5 m. The rear area
consists of pasture.
3. Grote Kolksluis (flood defence/lock). This concerns a lock which is open in daily
circumstances and thus in particular recreational sailing (commercial vessels
only in emergencies) gives the possibility to sail from the Black Water to theMeppelerdiep (a cannal) and vice versa. The lock is permanently closed during
the high water season and is therefore not operated. Closing takes place byclosing the flood doors in the outer head. The inner head is lower than the outer
head.
254

4. Meppelerdiepsluis (lock). This former lock was reopened in 2017 after four
years of renovation, but now as a lock. The outer head is higher than the innerhead. With water levels between NAP + 0.47 m and NAP -0.50 m, the lock isjust open. Outside of these water levels, the lock is activated and ships arelocked.
5. Gemaal Zedemuden (pumping station). This pumping station has several
milling operations, each with three reversing devices (check valve and two
automatic slides).
11.2.4

Intended dimensions
An inventory of expected shipping (recreational shipping and small vessels) has
shown that a passage width of 9.5 m is sufficient. Due to the depth of the passing
shipping a bottom height of NAP -3.0 m has been determined.
It was decided to realize the lock with a concrete U-barge with a length of 10 m,with slanted retaining walls on both sides. The lock plateau must be sufficiently
high to connect well to the dike bodies on either side. These dike bodies have aminimum deflecting height of NAP + 4.20 m. In order to limit the difference inheight with the dike bodies, the lock plateau will have a deflecting height of NAP+3.50 m. The lock plateau has a width of 20 m on both sides of the barrier lock.

11.2.5

Contemplated defense concept
The barrier concept is relatively simple. Under normal circumstances, the site lockis of course open. At higher water levels this is closed with the reversing means.
Given that for architectural reasons the reversing means may not be prominently
visible. A lifting slide is hereby immediately dispensed with as a turning means.
The Aremberger canal lock normally functions as a lock so long as the lock does nothave to be closed. Shunting with the Aremberger lock takes place with the aid of
rinkets (lock doors). (199 頁) With these rinkets (lock doors), controlled water canalso be drained from the bowl towards the Aremberger canal.
The lock should automatically close in case of approaching high water, but theoption of manual operation (both locally pressing the button and possibility withthe help of a pendulum or the like) should also be implemented. Partly for thisreason, the choice was made for point doors as a turning means.
25511.2.6

Layout of lock sluice in main lines
It has been indicated from management that baffle rebates must be fitted in order
to be able to dry the casing sluice for inspection and maintenance work. With this,the layout of the lock will look as follows:※（Rijkswaterstaat, Central government 2018）199 頁より作成。
Figure 66 Main dimensions of the lock at the Whaa
11.2.7

Construction and soil building

11.2.7.1. Data construction
From a structural point of view, the choice was made to build the lock in a closed
sheet piling and to build on the steel sheet piles that are required for this purpose.
An underwater concrete floor of 1.0 m thick with an underside at NAP - 4.9 m isinstalled. The underwater concrete is applied to a layer of supplementary sand thatis applied from a level of NAP - 6.0 m, see also Figure 67.

256200 頁※（Rijkswaterstaat, Central government 2018）200 頁より作成。
Figure 67 Construction pit sluice box lock the Whaa
The abutments are also founded on steel sheet pile screens. The sheet pilingscreens under the bank lock and the abutments can be seen in the overview
drawing below. The required penetration depths were determined by the
manufacturer at NAP - 10.75 m for the lock box or NAP - 10.00 m for theabutments.

©Rijkswaterstaat, Central government, Netherlands (2018)257

Figure 68 Overview of dam wall screens at the lock the Whaa
11.2.7.2. Soil data
The available soil research does not show a completely unambiguous picture of thesubsurface. The most common picture, however, is that a water-retaining layer ispresent, the bottom of which is at about NAP-5 m to NAP-6 m. Below that, thepleistocene sand layer begins. This consists of moderately fine sand. See also thefollowing probe:
201 頁※（Rijkswaterstaat, Central government 2018）201 頁より作成。
Figure 69 Characteristic soil structure around the lock the Whaa
11.2.8Other data resulting from the preliminary design of the lock
From functions other than water defense, a bottom protection is present both
inside and outside the dike of the barrier lock, with a width of 9.5 m at the
beginning and 15 m at the end of the soil protection. This soil protection consists258

of rubble stone with grading 10-60 kg on a zinc piece. The length of this soil
protection is 15 meters.
With regard to use, the following is known:
If a level of NAP + 0.20 m is exceeded on the Black Water, the site lock will beclosed automatically with the wooden point doors. After closing the barrier,the internal level is brought back to NAP - 0.20 m. This level is maintained byusing the rinkets (lock doors) in the Aremberger lock. This happens
automatically.
From a water level of NAP + 1.5 m, the stability of the Aremberger lock canno longer be guaranteed because the return devices of the Aremberger lock
can then no longer reverse the overload.
The daily water level in the polder behind the Aremberger lock is NAP -0.50

m.
Other starting points are:

The construction is designed with 2100 visibility year.

Average outside water level in summer is NAP -0.20 m and winter NAP -0.40mThe climate scenario to be taken into account is W +Capping of the moisture drainage is not taken into account

Setting and subsidence do not play a roleCalculated with hydraulic preconditions database WBI2017_Vechtdelta_92_v01.sql



If the export location was chosen: ZW_1_9-2_dk_00389, which is located at a
distance of 83 meters from the lock the Whaa

202 頁
11.3

Elaboration height (HTKW)In this section, the required deflecting height of the lock sluice and adjacent abutments isdetermined. This is done on the basis of the step-by-step plan in section 5.1.3 of the chapter
on Elevation.
11.3.1

Step 1 Determine failure probability
The failure probability Peis, KW, HT is determined using the following formula:259

In which:
Pmax

Failure Chance for the entire dike section (standard route) based on thelower limit of the water law = 1 / 1,000 [1 / year]

ωFailure probability factor for height = 0.24 [-]Ndsn

Length-effect factor for height = 2 for dyke stretch 9-2 [-] (Appendix A ofHT

OI2014v4 [Reference 4.2])
This results in a failure probability of 1 / 8.330 per year (1.2E-4 per year).
11.3.2

Step 2 Determine critical flow of soil protection / strength of retardant
Behind the lock a bottom protection is present consisting of rubble stone grading
10-60 kg on a geotextile. The (deep average) critical flow rate uc is determined
here using the Pilarczyk formula (the use of other stability relationships is also
allowed, see Chapter 9 Soil Protection):

Here is:D[m] Characteristic element dimension. For granular materials: D = Dn50.
A Dn50 of 0.21 - 0.25 m belongs to a 10-60 kg crushing stone. 0.14 m isused in accordance with CUR 197 ([Reference 11.1]).

φsc[-] Stability parameter to take into account the influence of transitions
and the deviating hydraulic loads that occur here. For φsc, a value of 0.75
is kept belonging to rubble in a continuous layer with at least two layers ofstones.

Δ[-] Relative density Δ = (ρs - ρw) / ρw
ρs = specific weight of stones [kg / m3] = 2650 kg / m3
ρw = specific gravity of water [kg / m3] = 1000 kg / m3
Δ = 1.65 [-]ψcr[-] Shear stress parameter. ψcr = 0.035 for granular materialskh[-] Depth parameterkh = (1 + h / D) -0.2 for not fully developed speed profile
260

Here is:h = water depth [m] = NAP - 3.0 m - NAP - 0.2 m = 2.8 m
kr = roughness parameter [-] = 2Dn for crush stone = 0.48 m
Filling yields kh = (1 + 2.8 / 0.24) -0.2 = 0.60.
ksl[-] Slope factor = 1 (no incline)

kt[-] Turbulence factor. For this, kt2 = 1.5, which is consistent with203 頁
increased turbulence (common, non-uniform flow)g[m / s²] Gravitational acceleration (g = 9.81 m / s²)

Filling yields uc = 3.4 m / s.
For the critical transfer / overflow flow qc that may come from the perspective of
the soil protection over the artwork:

Here is:
Bsv

Current carrying width soil protection [m] = 9.5 m

B

Width of the crown of the artwork [m] = 9.5 m. In this specific case thetransshipment / overflow flow over the abutments does not end up in thelock chamber and thus does not burden the bottom protection behind thelock. So no account needs to be taken here.

uc

Critical flow speed soil protection [m/s] = 3.4 m/s

hbi

Inland water level compared to NAP [m] = NAP - 0.20 m

hbb

Height top soil protection [m NAP] = NAP - 3.0 m (connect to thresholdsluice)Filling yields qc = 9.5 m3 / s / m.
With such large inflows, dynamic aspects as a result of air inclusions under theoverflowing jet may play a role and the stability of the reversing devices cannot be
guaranteed. Therefore, the critical inflow rate is maximized at 1.0 m3/s/m (rule ofthumb).
261

11.3.3

Step 3 Determine the return heightWith the help of Hydra-NL, the required deflecting height can now be determined.
For this purpose Hydra-NL is started up in climate mode. It starts with a sheet pile
profile to be defined under the Profile tab. In this screen it is indicated that theangle between north and the axis of the artwork ψkw= 170 °. A height does nothave to be specified; this is determined by Hydra-NL in the calculation of thehydraulic load level.

204 頁

262

※（Rijkswaterstaat, Central government 2018）204 頁より作成。
Figure 70 Overview of the Profile tab in Hydra-NL
A dike section calculation is then started under the Calculation tab in which thevalues as determined in steps 1 and 2 are entered (see Figure 71). It should also be
noted that if a different visual year is chosen than the hydra-NL 'predefined' visual
years 2050 and 2100, the outcomes from Hydra-NL can be linearly interpolated or
extrapolated.
205 頁※（Rijkswaterstaat, Central government 2018）205 頁より作成。
Figure 71 Overview input screen calculation Hydra-NL
The result of the calculation is a required crown height of NAP + 2.18 m. Figure
72 shows the main illustration points of the Hydra-NL calculation. This263

immediately shows that there is overflow, the local water level is well above theflood height. The illustration points are needed in the next step.

※（Rijkswaterstaat, Central government 2018）205 頁より作成。
Figure 72 Main illustration points from calculation Hydra-NL
206 頁
11.3.4

Step 4 Verification of storage capacity
In this step it is verified whether the combining capacity is not exceeded at thecalculated turning height from step 3. The data from the illustration point of theHydra-NL calculation from step 3 is used as input.
With the rinkets (lock doors) of the Aremberger lock, the inflowing flow can betransported to the water sports area behind it. The storage surface is 20 · 106 m2
and the permissible level rise is 0.5 m, which results in a storage capacity of 10 · 106m3.
With the aid of the Water Level Gradient tool, it can be demonstrated whether the
storage capacity is not exceeded. This is basically done for both illustration points.
Sometimes it can quickly be seen that one of the illustration points is normative.
That is not the case here, however. After all, the water level is the same while thewave height is slightly higher (0.35 vs. 0.38 m) with a closed disaster pounding.
However, the angle of wave incidence is somewhat less favorable with an opened
disaster pounding (77.5 ° versus 55 °). Therefore, the verification is performed
for both illustration points. In this case only the normative calculation is presented.
264

To this end, the water level course is first determined with the aid of the Water
Level Course tool. Under the tab preconditions the database VechtIJsseldelta(Vecht IJssel Delta) -WBI2017 is added first. The correct boundary condition isthen selected. After this, the water level from the illustration point of the HydraNL calculation is entered under the Location - Water level gradient tab (see Figure73). The return time does not matter for this application.

※（Rijkswaterstaat, Central government 2018）206 頁より作成。
Figure 73 Entry screen tool Water level course
This results in the water level course at the selected output location (see Figure 74). With
the Export button the output can be written to an Excel file.
207 頁

265

※（Rijkswaterstaat, Central government 2018）207 頁より作成。
Figure 74 Output screen tool Water level course
With the aid of the water levels in this file, an assumption for the course of the
wave height during the high tidal wave and the formulas for the transfer/overflow
flow rate of section 5.2.3, the inflow volume can be calculated. Spreadsheets havebeen made available for the Dutch and Zeeland coasts and the Vecht delta at theHelspdesk Water [Ref. 11.3] and [Ref. 11.4] to make these calculations. These canalso serve as an example for other areas. Figure 75 shows the completed
spreadsheet for the case, with the following workflow:Columns A and B contain the water level gradient line as generated with theWater Level Gradient toolRow 1-9 contains a block with input data used in the inflow volume
calculation:the deflecting height of the retractors is the HBN from the Hydra NL
calculation, in this case NAP + 2.18 m



the width of the turning means of the artwork (9.5 m)the deflecting height of the abutments, in this case also NAP +3.50 m



the width of the abutments of the work of art (2x20 m)

the orientation of the artwork (important to determine the angle of wave
incidence), in this case 170 °

the normative wind direction from the Hydra-NL illustration point (alsoimportant to determine the angle of wave incidence), in this case266247.5 °. Note: there are load systems (such as the coast) where the wave
direction in the illustration point of the Hydra-NL calculation can deviate
from the wind direction. The wave direction must be taken over in the
spreadsheet and not the wind direction!



the wave height from the Hydra-NL illustration point, in this case 0.38 m

the gravitational acceleration (9.81 m/s2)

Row 11-14 contains a block with calculated parameters based on the input
data that are also used in the calculation of the inflow volume (forbackgrounds see section 5.2.3):(208 頁)

the angle of wave incidence is calculated on the basis of the orientation of
the artwork and the wave direction in the illustration point of the HydraNL calculation (note: this does not have to be equal to the wind direction)the reduction factor Yβ is calculated on the basis of the angle of wave
incidence (plays a role in the calculation of the overtopping flow)the reduction factor Ys is calculated on the basis of the angle of wave
incidence. This reduces the wave height at the transition from the ongoing wave directions.



In column C the course of the wave height in time is shown. In accordancewith section 3.6 of the chapter entitled Hydraulic loads, the wave height
follows the time course of the wind set-up. In this case, the wave height of 0 m
at T = -24 h increases to 0.38 m at T = 0 and decreases again to 0 m at T = 24h.



In columns D and E the inflowing flow per linear meter over the reversing
means and abutments is calculated on the basis of the formulas for the transfer/ overflow flow rate in section 5.2.3.



In column F the total flow is calculated that flows in over the entire artwork(reversals + abutments) per second

In column G, the flow from column F is multiplied by the time duration of atime step (in this case 1 hour but that varies per load system), after which incolumn H the cumulative flow is given.

Figure 75 shows that the maximum occurring transfer/overflow flow rate is equal
to 1.01 m3/s/m, which according to the imposed transfer/overflow flow rate of 1.0
m3/s/m is 39. The total inflow volume over the reversals and abutments amounts toapproximately 4,500,000 m3. This is smaller than the available storage capacity of267

20,000,000 m2 x 0.50 m = 10,000,000 m3. This completes the design process, aheight of (rounded) NAP + 2.20 m is sufficient for this artwork.
The above consideration is based on the assumption that the inflowing flow
through the rinkets (lock doors) of the Aremberger lock can be completely
removed. Suppose that this is not the case and that a more detailed considerationof incoming and outgoing volumes has shown that the inflow volume may notexceed 3,000,000 m3. In that case, the available cup storage would not be sufficient.
For the purpose of this case, this fictitious value of 3,000,000 m3 will be continued
and the design process will be continued with step 5 of the step-by-step plan.
__________________________________
39

This does not work on the coast because of the phase shift between intent and tide (seesection 3.6.1). Here, however, the maximum wave height can be manually combined withthe highest water level for verification.
__________________________________
209 頁※（Rijkswaterstaat, Central government 2018）209 頁より作成。
Figure 75 Example spreadsheet calculation inflow volume
211 頁
11.3.5

Step 5 Determine the height at which available storage space is not exceeded268With the aid of the calculation sheet from step 4 it is easy to determine therequired deflecting height that is required to not exceed the available storage space.
Here, the designer usually has the choice to only increase the turning means or toincrease both abutments and headers. In this case, the abutments are already sohigh that no transhipment takes place here. The only option in this case is toincrease the reversals.
If the reversing means are increased to NAP + 2.28 m, the inflow volume is3,000,000 m3. This is rounded off to NAP + 2.30 m. With this value, the case iscontinued.

※（Rijkswaterstaat, Central government 2018）211 頁より作成。
Figure 76 Adjusting the height of the wall in such a way that the storage capacity is notexceeded
11.3.6

Step 6 Determine recurring height with Hydra-NL
In this step Hydra-NL determines the clearance height corresponding to the
maximum transfer/overflow flow rate of 0.800 m3/s/m from step 5. The Hydra-NL
input screen is the same as in Figure 71, only for critical transfer -/overflow rate is
now 800 l /s/m entered.
From the Hydra-NL calculation follows an HBN of also NAP + 2.28 m. The
illustration point is as follows:269

212 頁※（Rijkswaterstaat, Central government 2018）212 頁より作成。
Figure 77 Main illustration points from calculation Hydra-NL with adapted criticaltransfer/overflow flow
It can be seen that the water level in the illustration point is (almost) the same andalso the wave height does not differ much (0.38 m to 0.40 m). It can therefore
already be assumed in advance that the cup storage is not exceeded (step 7). For
the sake of completeness, step 7 will still be completed.
11.3.7

Step 7 Check that cup storage is not exceeded
For the sake of brevity, the wave height of 0.40 m associated with the illustration
point Closed disaster pounding is combined with the water level of NAP 2.80 m
associated with the illustration point Opened disaster pounding. The mostunfavorable angle of wave incidence (225 °) is also chosen from both illustration
points. This results in an inflowing volume of approximately 2,850,000 m3. The
storage capacity is now not exceeded. A height of NAP + 2.30 m is sufficient.

270

※（Rijkswaterstaat, Central government 2018）212 頁より作成。
Figure 78 Check whether the combing capacity is not exceeded
It should be noted that in this case the illustration point in the adapted Hydra-NL
calculation deviates little from the first calculation. That does not always have to be
the case! That is why an example is given in the next section where this is not thecase.
11.3.8Elaboration with smaller cup storage
Suppose that the Aremberger lock is closed simultaneously with the closure of thebarrier lock. In that case the available storage space is determined by the maximum
permissible water level of NAP + 1.50 m in connection with the stability of theAremberger lock. (213 頁) The available combing capacity is then NAP + 1.50 m NAP + 0.20 m (closing level) = 1.30 m x 25.000 m2 = 32.500 m3.
Steps 1 through 4 are identical, so that the verification is continued with step 5.
Step 5 Determine the height at which available storage space is not exceeded withthe help of the calculation sheet from step 4 the required turning height is again
required for the storage capacity not to exceed. A height of NAP + 2.85 m is thenrequired. The case is continued with this value.

271

※（Rijkswaterstaat, Central government 2018）213 頁より作成。
Figure 79 Adjusting the height of the wall in such a way that the storage capacity is notexceeded
Step 6 Determine the return height with Hydra-NL
In this step Hydra-NL determines the deflection height corresponding to the
maximum transfer / overflow flow rate of 0.065 m3 / s / m from step 5. The input
screen of Hydra-NL is the same as in Figure 71, only for the critical transfer - /overflow flow rate is now entered 65 l / s / m.
From the Hydra-NL calculation follows an HBN of NAP + 2.87 m. This is in linewith the calculated required crest height of NAP + 2.85 m on the basis of the waterlevel and wave height from the illustration point from step 4. illustration point now
looks like this:272

※（Rijkswaterstaat, Central government 2018）213 頁より作成。
Figure 80 Main illustration points from calculation Hydra-NL with adapted criticaltransfer/overflow flow
214 頁
It can be seen that the water level deviates in particular from the illustration point
associated with a closed Disaster pounding (NAP + 2.61 m around NPA + 2.80m). The same applies to the wave height (0.70 m to 0.38 m). The water level (NAP
+ 2.74 m around NAP + 2.80 m) and wave height (0.52 m by 0.38 m) also slightly
deviate from the illustration point that is associated with an opened Disasterpounding.
Note: this step looks a bit different on the coast. Due to the phase shift between
the tide and water level set-up (see section 3.6.1), the highest water level must be
combined manually with the maximum wave height. This transhipment flow, whichis greater than the maximum transhipment flow from the storage container, must
be entered in Hydra-NL. In Hydra-NL, the phase shift between tide and waterlevel set-up is not taken into account.
Step 7 Check whether cup storage is not exceeded Started by determining thewater level course associated with a water level of NAP + 2.61 m and NAP + 2.74
m respectively. The output is exported to an Excel file.

273

※（Rijkswaterstaat, Central government 2018）214 頁より作成。
Figure 81 Entry screen new calculation tool Water level course
Started with the illustration point that belongs to an opened Disaster pounding. It
can be seen that with a deflecting height of NAP + 2.85 m the capacity of 32.500
m3 is exceeded slightly (inflow volume around 35,000 m3):※（Rijkswaterstaat, Central government 2018）214 頁より作成。
Figure 82 Checking whether combing power is not exceeded at illustration point opened
Disaster pounding and crown height 2.85 m + NAP at a returning height of NAP +2.86 m, the available storage space is sufficient. This is almost equal to thecalculated HBN of NAP + 2.87 m.
The illustration point associated with a closed disaster pounding is also checked. It
can be seen that with a deflecting height of NAP + 2.85 m, the composting
capacity of 32,500 m3 is also just exceeded (inflowing volume around 34,000 m3).
(215 頁) At a returning height of NAP + 2.86 m, the available storage space now274also meets the requirements.

※（Rijkswaterstaat, Central government 2018）215 頁より作成。
Figure 83 Checking whether combing power is not exceeded at illustration pointclosed Disaster pounding and crown height 2.85 m + NAPGiven the fact that the formulas from the Guidelines for Art Works 2003 withwhich the transfer/overflow flow rate is determined to be somewhat conservative, acrest height of NAP + 2.85 m is considered appropriate for this artwork.
11.3.9Tightening with the help of EurOtop2016
With the rules from the EurOtop2016 the required crown height can be
determined even more sharply. This can be done by using Figure 84:Determine the relative freeboard of the barrier Rc/Hm0. In this case thefreeboard is equal to NAP + 2.87 m (the required crest height calculated with
Hydra-NL) - NAP + 2.74 m + NAP (water level in the illustration point of theHydra-NL calculation open disaster pounding) = 0, 13 m. The wave height in
the illustration point of the Hydra-NL calculation is 0.52 m. The relative
freeboard therefore amounts to 0.13 / 0.52 = 0.25. For the illustration point of
the closed Disaster pounding the relative freeboard is 0.26 / 0.70 = 0.37. The
latter is normative.

The relative throughput rate q/(gHm03) 0,5 is 0.065/(9.81 * 0.703) 0.5 = 3.54E-2
in the illustration point of the closed Disaster pounding and 0.065 / (9.81 *0.523) 0, 5 = 5.87E-2 in the illustration point of the opened Disaster pounding.
As a check, these values are shown in Figure 84 (green = situation open
Disaster pounding, blue = closed Disaster pounding).



In the case of a relative overtopping rate of 3.54E-2, a relatively freeboard of
0.17 should be used if the formulas from EurOtop2016 are used (see dotted275

blue line from the figure below). This means a freeboard of 0.17 * 0.7 m =0.12 m. The required crown height is NAP + 2.61 m + 0.12 m = NAP + 2.73
m. This is 0.14 m lower than the crest height of NAP + 2.87 m calculated with
Hydra-NL. To check: the difference in the relative freeboard is 0.20, which
also amounts to 0.20 * 0.7 = 0.14 m.
216 頁※（Rijkswaterstaat, Central government 2018）216 頁より作成。
Figure 84 Tightening required crown height on the basis of EurOtop2016
The same result is found when formula 7.2 is used from EurOtop2016:

Describing provides the following formula:

Filling yields (with q = 0.065 m3 / s / m and Hm0 = 0.70 m) also here an Rc of 0.17,276

or a freeboard of 0.17x0.7 = 0.12 m and a required crown height of NAP + 2.73 m.
11.4

Do not close elaboration (BSKW)
In this chapter, the configuration of the reversing devices is determined. This isdone on the basis of the step-by-step plan in section 4.1.3 of the Non-closing
chapter.
The primary function of the artwork concerns the passage of shipping traffic andfrom that function the artwork should always be open under normal circumstances.
This implies that the function of high-water traffic during the primary function is
not filled. In order to activate this function, certain actions are required, such as
signaling the closing level, curling shipping and closing the turning gear.

217 頁
11.4.1

Step 1 Simple design rules
In this step, it is determined whether the functioning and configuration of thereversing means can be controlled in such a way that the failure mechanism cannot
be tapped at the site lock by means of simple design rules. A further analysis of the
failure mechanism is no longer necessary in that case, because it is already clear inadvance that the artwork with that particular operation and configuration has anegligible contribution to the risk of flooding.
Looking at the primary function of the artwork, the simple design rules do not
apply to this site lock. The primary process, the passage of ships, does not allow theartwork to always be closed high water. Specifically, this failure mechanism must be
designed.

11.4.2

Step 2 Determine failure probability
The failure probability Peis, KW, NS is determined with the help of the following
formula, where the basis for the values of the various parameters is given below:

In which:
277

Pmax

Failure Chance for the entire dike section (standard route) based on thelower limit of the water law = 1/1,000 [1/year]

ωHT

Failure probability factor for closing reliability = 0.04 [-]NNS

Length effect factor for closing reliability = 4

The value for the length-effect factor was determined on the basis of an analysis of
the other structures in the dyke section. There are 5 artworks in the process. These
are further checked below for non-closing.
1.

Gemaal Kadoelen (a polder pumping station in Amsterdam-Noord): Because
the closure is provided by two independent retractors and these reversing
devices close automatically when the pump stops, the failure probability
contribution of this artwork to non-closing is negligibly small.

2.

Gemaal Barsbeker (pumping station): The auger pumping station has a nonreturn valve that automatically closes after jacking and also an emergency slidethat automatically closes when a high water is present. As a result, there are no
two independent reversing devices that close after each meal request and thus
turn the work of art high water twice outside of the time used. However, it is
known from VNK's analysis that the probability of failure is not negligible. The
reasons for this are the height of the discharge points, the presence of a nonreturn valve, the presence of an emergency gate that closes automatically inthe event of high water or when the non-return valve does not close and thelimited flow area between auger and trainer. The artwork is not taken into
account in the length effect for not closing due to the above.

3.

Grote Kolksluis (flood defence/lock). This lock is closed as standard during
the high water season. In the summer season, however, this is not the case andit has one set of high water-pivoting point doors. A second barrier can then be
built up with the aid of bulkheads. For this artwork applies that this is includedin the length-effect for not closing.

4.

Meppelerdiepsluis (lock). This lock is fully open at certain water levels.
Outside it is shaken and the outer head can turn a higher water level than the
inner head. On this basis it cannot be said that the artwork has a negligible
failure probability with regard to non-closing and is therefore included in thelength effect.

5.

Gemaal Zedemuden (pumping station). Each mill has three reversals, two of
which are not entirely independent. This in any case leads to two independent
reversing means that close when the pump (s) stop grinding.
278

(218 頁) The failure probability contribution with a view to non-closing istherefore negligible and the artwork is not included in the length effect.
The lock is artwork number 6 in the dyke section. Finally, the manager
indicates that it is quite possible that in the future another work of art (inlet
sluice) will be added to the dike section.
On the basis of the above, four works of art with a non-negligible contribution
to the failure probability for non-closure are taken into account (Grote
Kolksluis (pumping station), Meppelerdiepsluis (lock), Keersluis (flood
barrier) the Whaa and the possible future artwork). This makes the lengtheffect factor NNS equal to 4.
From the above follows a failure probability for not closing 1/100,000 (= 1.0E-5)
per year (see formula 10.4).
11.4.3

Step 3 Determine maximum admissible inflow volume (cup storage)
When the casing lock does not close and the outside water level rises, water flows
through the casing sluice and enters the bowl between the casing sluice and theAremberger lock. The contents of this bowl have the following characteristics(assuming a closing level of NAP +0.20 m):

Table 21 Water levels in relation to cup storage
Maximum indoor

Coming surface

water level

Compressive

Effects

Capacity

NAP + 0,50 m

8.750 m²

2.625 m³

Bowl filled to edge banks

NAP + 1,00 m

25.000 m²

20.000 m³

Substantial flooding inbowl

NAP + 1,50 m

25.000 m²

32.500 m³

The security of theAremberger lock is nolonger guaranteed andsubstantial flooding in
the basin※（Rijkswaterstaat, Central government 2018）218 頁より作成。
When the rinkets (lock doors) of the Aremberger lock are opened when the closing279

level is reached, a larger cup-storing surface is available. Initially, only the cup
storage in the bowl is assumed, with the maximum admissible water level NAP +1.50 m in the bowl.
11.4.4

Step 4 Determine critical flow from soil protection
The critical flow from the soil protection on the inside depends in the first instanceon the critical flow rate with respect to this soil protection. This critical flow rate
has already been determined in section 11.3.2. It follows that uc = 3.4 m / s.
The critical inflow rate depends on the inland water level and the way the waterflows inwards. The latter relates to the modeling of the situation. In the present
case there is a so-called low threshold, in which the question is whether it is acomplete or imperfect flow at the moment when the work of art is not closed highwater.

11.4.5

Step 5 Determine maximum permissible outside water level
In this step, this outside water level must be sought, which is maximally present
during a discharge wave, without this leading to an overrun of the storage space or
the exceeding of the critical flow rate of the soil protection.

219 頁
11.4.5.1. Chances of exceeding the outside water level
In order to gain insight into the exceedance probability of the various outside waterlevels, a line with exceedance probabilities can be made using Hydra-NL. To create
an exceedance frequency line, it is not necessary to create a profile in Hydra-NL.
After the program has started you can go directly to the tab 'Calculation' and forthe type of calculation you have to choose 'Water level'. Subsequently, it can beindicated for how many frequencies and which frequencies the exceedance
probability of the water level must be determined (see Figure 85). The following
restrictions apply from Hydra-NL:


Maximum frequency is 1/10 per year

Minimum frequency from backgrounds Hydra-NL is 1/100,000 per year. At
lower frequencies Hydra-NL indicates that the calculation results are lessreliable.



Absolute minimum frequency is 1/1,000,000 per year

280

※（Rijkswaterstaat, Central government 2018）219 頁より作成。
Figure 85 Entry screen Hydra-NL determination of exceedance opportunities outside waterlevel
In order to make the exceedance frequency line for the future, one of the'predefined' view years 2050 or 2100 must be chosen. It should be noted that if thedesign opts for a different visual year than 2050 or 2100, the results from HydraNL can be linearly interpolated or extrapolated.
For the insight it is recommended to also make an exceedance frequency line forthe visible year 2023.
For the hydraulic boundary condition of the lock sluice, the above analysis has been
carried out and this leads to the following graph.

281

220 頁※（Rijkswaterstaat, Central government 2018）220 頁より作成。
Figure 86 Overwater odds outside waterway lock the Whaa based on Hydra-NL
For water levels with a greater probability of exceedance than 1/10 years, local
water level statistics may be used if initially available. If enough local measurement
data are available, the statistics for larger exceedance frequencies can be derived on
this basis. Local measurement data can, for example, be found via the website
https://waterinfo.rws.nl for the case of the lock the Whaa, this has taken placebecause the open turning height is below the outside water level with anexceedance probability of 1/10 per year and thus has a higher frequency and thus
falls outside the range of Hydra-NL. On the basis of the local water level statistics,
the graph above has been extended to figure 87. Use has been made of 30 years ofwater level data.
This figure shows that local water level data at the lock the Whaa does not directly
match the calculations with Hydra-NL40. One of the causes may be that the time
period over which the water level data is available is not long enough. A thoroughanalysis requires a period of at least 50 years if one is interested in exceedance
probability of 1/10 per year. In addition, there are a number of other (possible)282

causes which are not discussed here, but which are known to the Helpdesk Water.
The case as this has now been detected at the Whaa lock has been submitted to theHelpdesk Water. In consultation with this helpdesk we finally reached theexceedance opportunity line as shown in Figure 88.
_______________________________
40

Possible differences between Hydra-NL and local water level data differ per location. It

can therefore also happen that the data connects nicely.
________________________________
221 頁※（Rijkswaterstaat, Central government 2018）221 頁より作成。
Figure 87 Local water level data processed in excess water level283

※（Rijkswaterstaat, Central government 2018）221 頁より作成。
Figure 88 Design plan regarding the exceedance opportunities of the outside water level
11.4.5.2. Expiration of high-water wave
To view the course of the inland water level when there is an inflow through a nonopened work of art, use can be made of the discharge wave. This can be
determined with the help of the Water Level Course tool. This tool has alreadybeen described in chapter 3.
222 頁
In the Water Level Course, a high water wave is described by means of a period oftime and a certain course of the outside water level in this period of time. This
course can consist of several routes. For the precondition point at lock-in the
Whaa, the following sequence is present in the tool.

284

※（Rijkswaterstaat, Central government 2018）222 頁より作成。
Figure 89 Expiration of surge wave surge barrier the Whaa in water level course
The outlined process is always present, independent of the peak of the high tidewave. So the water level difference between the beginning and the peak of the wave
is always 1.6 m and in addition the duration of the wave is always 576 hours. Thismeans that when the maximum permissible inland water level at a low peak waterlevel in the discharge wave is already reached, the application of the fixed course as
shown in Figure 89 leads to a somewhat remarkable situation, which is made clear
in the following example.
Suppose that at the peak of the discharge wave of NAP + 0.5 m the criterion of
the inland water level is also exceeded. In that case, the outdoor water level
starts at NAP + 0.5 m - 1.6 m = NAP - 1.1 m. This water level is well below
the average daily water level in the winter period of NAP - 0.40 m. So that is
bad unlikely. On the other hand, a high value of the peak water level would
also lead to a situation that is not unambiguous. Suppose that at a peak waterlevel of NAP + 2.0 m in the high water wave exceeds the storage space, thisleads to an outside water level of NAP + 2.0 m - 1.6 m = NAP + 0.40 m prior
to the high water wave. This water level is again 0.80 m above the average
daily water level.

285

In order to avoid the above points with the current instruments, the form of thedischarge wave (duration and location of the break points) from the Water Level
Course tool is used in this case41, but the water level increases are scaled relative tothe situation with a water level increase of 1.6 m from water level course. This has
been made clear in the figure below. The various inland water levels as mentioned
in Table 21 are included.
_________________________________
41

This principle has been used here because there are currently no other tools available tomodel the flood wave depending on the peak water level. This does not affect the fact that
one can also choose another starting point, provided that this is well documented.
__________________________________
223 頁※（Rijkswaterstaat, Central government 2018）223 頁より作成。
Figure 90 Expiration of the high water wave at the various outside water levels
Because the storage capacity of the bowl between the old and new flood defense islimited, an outside water level higher than NAP + 1.50 m quickly leads to an inland
water level, given an unsealed lock, to be higher than NAP + 1.50 m. stability of
the Aremberger lock can no longer be guaranteed.

286

11.4.5.3. Course inland water levelNow that the course of the floodwaters is known, it is possible to calculate how theinland water level behaves as soon as water enters the water during a high water
wave due to the artwork that has not been closed. In view of the very limited
dimensions of the bowl, the inland water level runs directly with the outside waterlevel. The course of the inland water level is therefore equal to that of the outside
water level.
The course of the flood water from the above subsection is therefore not used any
further when following the next steps. The analysis carried out in this section is inparticular included as an example of a possible approach to a cup storage where thecourse is important.
11.4.5.4. Permissible outside water level
The fact that the inland water level can immediately follow the outside water level(see section 11.4.5.3) means the following:

A maximum outside water level of NAP + 1.50 m is permissible from storage.

A critical flow rate of 3.4 m / s is permissible from soil protection. This flowrate is not exceeded because the inland water level is almost the same as theoutside water level. With a water depth on the inside of (NAP - 0.4 m - NAP 3.0 m) = 2.6 m, at a critical flow rate of 3.4 m / s, a critical flow rate of 3.4 ×
2.6 = 8.84 m³ / s / m. When this is stopped in the formula for the flow of a low
threshold (imperfect flow), this results in a water level difference of 0.60 m(see below) for the bottom protection to collapse.

224 頁
In view of the limited composting capacity, this decay will not occur and so the soil
protection will not be decisive. The maximum permissible outside water level will
be equal to NAP +1.50 m on the basis of the above considerations.
11.4.6

Step 6 Determine the probability of not being turned upside-down of the artwork
This step involves determining the factor Popen. It has to be determined what the287

chance is that from the primary function of the artwork the artwork is alreadyclosed at the moment that a high water presents itself. For the lock sluice it isalways open and only closed if this is required from high tide times. This makes
Popen equal to 1.
11.4.7

Step 7 Determine the required chance of closing the reversing means
The maximum permissible outside water level that may occur during a high water
wave when the artwork is open and the chance that the artwork is open at the
moment of high water is now known. With this, the required failure probability ofclosure can be determined from the failure probability for not closing. This does
not take into account a possible recovery of a failed closure in an alternative
manner (Pf,herstel= 1). The probability that the outdoor water level will exceed NAP+1.5 m will be set at 0.14 per year with the aid of the exceedance chance line
(Figure 88).

The probability of not closing Pns should therefore be less than or equal to 7.14E 05
per question.
11.4.8

Step 8 Verify that the chosen locking devices meet the requirement in step 7
The first set-up of the site lock consists of the use of a single set of high waterretaining reversals. The most obvious solution is to use a set of point doors. In theconcept of the foundation (see section 11.2.5) it is indicated that shot-bar rebates
must also be made. However, these serve for bulkheads that are used in case ofmaintenance. For the time being, they are not taken into account for turning a highwater, because the placing of the bulkheads in case of strong wind is rather
uncertain.
Because the reversing means are only closed when a high water is present, the newscore tables ([Ref 4.5] and [Ref 11.2]) can be used to determine the probability of
failure of the reversing means. Based on the assumption that in the new situation,
as far as organization is concerned, all the conditions in these score tables are fully288

met, the next score for Pns is feasible when one set of high water-retaining
overhead doors is used.
225 頁
Assessment aspect

Score Ei

Probably not[-]

close Pns
[1 question]

Alarm

7

1,00E-07

Mobilization

5

1,00E-05

Service5

1,00E-05

Technical failure

3,5

3,16E-04

Total

3,36E-04※（Rijkswaterstaat, Central government 2018）225 頁より作成。
This shows that the requirement is not met in step 7 (section 11.4.7). This saves anotherfactor 5.
There are now several options:1.

The area behind the Aremberger lock is also involved in cup storage.

2.

The use of the lock is adjusted

3.

Additional retractors are placed.

These three options are discussed in the following paragraphs.
11.4.8.1. Increasing cup storage (back to step 3)
By also using the cup storage behind the Aremberger lock, the cup storage isgreatly increased. To this end, the flow capacity of the rockets in the doors of theAremberger lock must be sufficient so that no outside water level higher than NAP+ 1.50 m occurs at this lock, which could lead to instability of the lock. When thewater level at the Aremberger lock becomes larger than NAP + 1.50 m and thislock collapses, an uncontrollable situation occurs. Due to the large storage surface
behind the lock, however, it is still very possible that large consequences are notpossible.
A larger cup storage may help to meet the failure probability if the exceedance
probability of the maximum allowable outside water level during a high water wave
(peak water level) is a factor of 5 smaller than the exceedance probability of NAP +289

1.50 m. The latter had an exceedance probability of 0, 14, so the searched outside
water level may have a maximum probability of exceedance of 0.14 / 5 = 0.028 peryear.
An excess water level (see Figure 88) of approximately NAP +2.0 m is associatedwith this exceedance. This outside water level does not lead to the overflow of theold flood defense, but the flow velocities around and through the Aremberger lock
will be large. At a target level of NAP -0.80 m and an outside water level of NAP+2.0 m, flow velocities occur of approximately 7.5 m / s (Ѵ(2·g·ΔH)). It is expectedthat the Aremberger lock and the immediate vicinity will not withstand such flow
velocities, which will increase the breach in the old defense.
Based on the above considerations, it is not considered desirable to solve theshortage of failure probability by taking into account the cup storage behind theAremberger lock.
11.4.8.2. Adjusting the use of the barrier lock (back to step 6)
There are two options for this solution direction:
1.

Reducing the chance that the artwork is open

2.

The installation of a lock locks instead of a barrier lock. In fact, this is a result
if option 1 is implemented very far.

The second option is not acceptable. After all, the starting point is to make a lock,so that shipping can sail in and out freely.
226 頁
Option 1 can possibly be realized by closing the floodgate at night as norecreational boating is present. By doing this, the chance of open standing (Popen)
reduces to 0.5. The requirement of the probability of failure of the closing of thetip doors then reduces from 7.14E-05 per demand to 1.43E-04 per question. In
addition, the chance of failure per closure also decreases because the reversing
device is now operated every evening and in the morning. This increases thereliability, provided that management and maintenance are carried out correctly.
Based on the standard failure probabilities (see Appendix B), there is a risk of not
closing 1.0E-04 per question. This means that one set of point doors meets therequirement for not closing.

29011.4.8.3. Additional reversals (back to step 7)
By adding another set of retractors, the reliability of the closure is of course
increased. There may not be a full correlation between the reversing means. Thismeans, among other things, that there must be sufficient distance between thereversing means.
If the failure probability of closure is determined for two reversals using the score
tables, then the following scores are obtained:
Assessment aspect

Score Ei

Probably not[-]

close Pns
[1 question]

Alarm

7

1,00E-07

Mobilization

5

1,00E-05

Service5

1,00E-05

Technical failure

4,5

3,16E-04

Total

5,17E-05※（Rijkswaterstaat, Central government 2018）226 頁より作成。
The value for Pns now becomes 5,17E-05 per question, where the requirement was
7,14E-05 per question (see paragraph 11.4.7). The requirement is therefore met.
A solution with two sets of retractors thus leads to a situation that meets therequirements with respect to non-closure.
11.4.8.4. Selectable design concept for not closing
On the basis of the analyzes carried out, it appears that both reducing the open
period (adaptation Popen) and making a second set of point doors (adaptation Pns)
leads to meeting the requirement. Which solution is ultimately chosen should be
discussed with the client.
From the primary function of the casing lock, the provision of an additional set ofpoint doors can be the most desirable. The primary function (passing throughshipping) is not affected by this and there is the 'certainty' that if something
happens to the one set of point doors, one immediately has access to an extra set ofdoors.
291

From cost (installation and maintenance) the adjustment of the operating time ispreferable.
11.5

Elaboration of piping (PKW)In this section the required dimensions of the seepage barriers around the barrier
and adjacent abutments are determined. This is done on the basis of the step-bystep plan in section 6.1.4 of the Piping chapter.

11.5.1

Step 1 Determine design decay about the artwork
The design water level is determined using Hydra-NL. Here, a water level sum isrotated in which the water level is determined with an exceedance probability equal
to the lower limit (maximum permissible failure probability) of the dyke stretch (1/ 1,000 per year).

292

227 頁※（Rijkswaterstaat, Central government 2018）227 頁より作成。
Figure 91 Overview of Hydra-NL water level calculation input screen
This design water level is 2.52 m + NAP.

※（Rijkswaterstaat, Central government 2018）227 頁より作成。
Figure 92 Overview of the Hydra-NL water level calculation output screen

293For the inland water level, a value of 0.20 m-NAP is used, being the water level atwhich the level after closing is brought by the rinkets (lock doors) of theAremberger lock. In view of the small area behind the bank lock, no account needs
to be taken of the deviation under normative conditions. The design decay thus
amounts to 2.52 m + NAP - 0.20 m-NAP = 2.72 m.
11.5.2

Step 2 and 3 Determine whether there is sufficient seepage length sufficient
In this case, many seepage screens already exist from constructive considerations.
This section assesses whether the dimensions are sufficient.

228 頁
In this case it already seems clear from a qualitative view that piping is not a
relevant failure mechanism. The work of art is enclosed by a thick package ofimpermeable layers (at least between soil level 3.0 m-NAP and 5.0 m-NAP clay /peat is present). However, in order to be able to completely shut off piping, theunderlying sand layer must also be assessed. This requires an additional calculationthat is more work than performing a simple piping view.
The artwork meets a simple heave test. The design decay is 2.73 m and the lengthof the downstream seepage screen is NAP - 10.0 m (depth of land screens) - NAP 3.0 m (bottom level sluice) = 7.0 m. The transition over the downstream seepage
screen thus amounts to 2.73 / 7.0 = 0.39. This is smaller than the heave criterion of
0.5 so that underflow can be excluded on the basis of this simple heave
consideration.
Only backwardness may therefore play a role. Figure 93 shows a 3D representationof the artwork in which the possible normative seepage route has been included.
Here, the dike is schematized as a clay dike (known from the statutory assessmentof the dike body). The following seepage is normative:
Table 22 Overview of seepage lengths normative seepage
No.

Description

Length1

From soil level 3.0 m-NAP to lower level clay layer at 5.0 m-NAP

Lv = 2 m

2

From the side of the lock chamber to the side of the land on level 5.0 m-

Lh = 20 m

NAP
3From the front of the manor to the back of the head of the land at level
5.0 m-NAP. Note: this is a so-called 'short path'. It is unlikely that the294

Lh = 9,9 m

groundwater flow follows the 'notch' in the sheet piling back to thecolumn wall.
4

From side of land to side of lock chamber at level 5.0 m-NAP

Lh = 20 m

5

From level underside clay layer to 5.0 m-NAP to level exit point (= soil

Lv = 2 mlevel) 3.0 m-NAP※（Rijkswaterstaat, Central government 2018）228 頁より作成。

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）228 頁より作成。
Figure 93 Overview of normative seepage along the work of art
Because the normative seepage route also contains vertical parts, Lane's formula isused. Filling in (with Ccreep = 7 belonging to moderately fine sand):

229 頁

The design decay is 2.72 m smaller than the critical drop of 2.95 m. So no
additional seepage screens are needed.
11.6

Effective structural failure295

In this section the design of the lock is verified against the reliability requirementswith respect to structural failure from the Water Act and the Building Decree.
Within the WBI, structural failure is only considered as a result of the high waterload and the mechanism Strength and stability is called point constructions(STKWp). In the case of designs, however, the artwork must be verified withregard to all possible loads, so STKWp is not complete. Given the focus of theWork Guide, the example does limit itself to the design verification with regard to
the high water load situation. To this end, the strength of all water-retaining
components must be verified in practice (event 2, see section 7.3), as well as theoverall stability of structure and ground body (event 4, see section 7.3). In the caseonly the verification of the main water retaining element, the wooden gaps, isdiscussed. Because this concerns a case, only one structural part of the doors isverified, namely a horizontal beam. The verification is done on the basis of thestep-by-step plan in section 7.9 of the chapter Structural failure.
Figure 94 shows a schematic view and cross-section of the wooden point doors.
The crest height as determined in section 11.3 is maintained. The wooden pointed
doors can be roughly schematized as a number of horizontal girders that areconnected by two resins against which planking has been installed.

296

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）229 頁より作成。
Figure 94 Schematic representation of structural design wooden point doors of the lock The
Whaa
230 頁
11.6.1

Step 1: choose the construction component to be verified
In this case, the dimensions of the horizontal wooden beam are verified at a heightof NAP -1.00 m.

11.6.

2 Step 2: determine the relevant taxes
The beam must be able to withstand the loads at high water, or the combination of
the hydraulic load and the self-weight load. The beam may also have to withstandice load and temperature load (see Table 11). In this case, however, only the highwater tax is discussed.

11.6.3

Choice A or B: design verification regarding high water or other loads
297Given the scope of the example: choice A in Figure 33.
11.6.4

Step 3: determine the reliability requirement from the Buildings Decree
The lock is part of the primary flood defense, in practice in this case Consequence
Class (CC3) is usually required. However, if the route standard from the Water Act
involves a major probability of flooding (a flexible standard) and CC3 requires
disproportionate investments, it may be sensible to deviate from this and to bring
the reliability requirement from the Buildings Decree in line with that of the Water
Act. In that case, for example, CC2 may be required. However, this is up to theclient.
In the example, the client requires CC3, or βeis, BB = 4.3 for a lifespan of 100 years.

11.6.5

Step 4: determine the reliability requirement from the Water Act
The failure probability Peis, KW, CON is determined using the following formula:

In which:
Peis, KW, CON

Failure Chance for structural failure and no failure by overflow /transhipment of an individual work of art derived from route law
from the Water Act for a reference period equal to tref = 1 year
[-]

Pmax

Failure Chance for the entire dike section (standard route) basedon the maximum permissible probability of flooding from thewater act for a reference period equal to the tref = 1 year [-]. Pmax
= 1 / 1,000 [1 / year]

ωCON

Failure probability factor for structural failure = 0.02 [-]cCorrection factor for the correlation between structural failureand failure by overflow / transshipment = 4 [-]Ndsn

Length-effect factor for structural failure = 3 [-]This results in a failure probability of 1 / 37,500 per year (2.67E-5 per year). Thisrequirement is formally related to failure, or all events that, from a structural pointof view, lead to a flood. As indicated in section 7.4, in the case of 'designs' it is298

recommended that this requirement with regard to failure as a result of collapsingwater-retaining construction components equates to initial failure, or the failure ofwater-retaining construction components.
11.6.6

Step 5: collect the data from the construction partThe center line of the wooden beam is at a height of NAP-1.00 m and is executedin Azobé (tree of the family Ochnaceae). The beam has a length of 4.2 m, a height(y axis) of 400 mm and a width (z axis) of 300 mm, see Figure 95.

231 頁©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）231 頁より作成。
Figure 95 Dimensions cross-section beam
11.6.7

Step 6: select strength magnitude to be determined and determine the limit statefunction / unity check in the example, the recordable stress in the middle of thebeam, in the design dimensions from step 5, becomes the strength magnitude to beverified.
Load on the girder
In the high water load situation the girder is loaded by the hydraulic load p (acting
in the y direction and leading to bending stresses on the z axis), the own weightload q (acting in the z direction and leading to bending stresses around the y -as)and a spatial force N (pressure force in the x-direction). We assume conservatively
that the sheet metal only transfers the hydraulic load to the beams and does not
add any strength itself. The beam is schematized as a beam on two hinged support
points.

299

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）231 頁より作成。
Figure 96 Loads on the beam
The splash force N is a typical load associated with point doors and results from thehydraulic load.

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）231 頁より作成。
Figure 97 Distraction of the spatial force I
232 頁

Figure6-5 Forces on point door
The reaction force S can be dissolved in a force parallel to the door (N)and a force perpendicular to it (F). These reaction forces can be
written as a function of the water pressure W and the angle α that the300

doors make with the normal on the lock shaft (Figure 6-5).

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）232 頁より作成。
Figure 98 Derivation of spatial force II
The point doors of the turn lock the Whaa are supported at an angle of a = 22 °against each other which leads to the following force:Strength of the beam
Wood is an anisotropic material, which means that the material properties differ
per direction of orientation. Figure 96 shows that the beam is loaded in threedifferent directions, which means that three different strength properties play arole in the relevant stress verification.
Border status function / unity check
For the verification of the maximum voltage to be absorbed by the beam, article
6.2.4 from the NEN-EN 1995 (Eurocode Wood) is used, which has alreadytranslated the limit state function for the load situation to be verified (Figure 96)
into two prescribed unity checks (formulas 6.19 and 6.20) expressed in calculation
values:

233 頁
At which:301

Calculation value for axial compressive stress [N / mm2]
Calculation value for axial compressive strength [N / mm2]
Calculation value of bending stress around y-axis [N / mm2]
Calculation value of the bending strength when bending around the y-axis [N /mm2]
Calculation value of bending stress around z-axis [N / mm2]
Calculation value of the bending strength when bending around the z-axis [N /mm2]Km

0.7 [-] (rectangular cross-sections)
In this case, bending around the y-axis is caused by the self-weight load (q) and thez-axis by the hydraulic load (p).

11.6.8

Step 7 and 8: determine the representative value and calculation value of thestrength
In this case the strength is expressed in three different strength terms (fc,0 , fm,y, andfm,z) for which the representative values and calculation values have been derived
with the help of NENEN1995, NEN-EN338 and NEN-EN1912. The tip doors are
made of Azobé (wood class D70 in accordance with NEN-EN1912) and climateclass 3 is considered applicable. The load duration class for the hydraulic load isshort (less than 1 week).
The relationship between the representative and calculation value of the strength isequal to:Table 23: representative strength and calculation values of the strength
Azobé (D70)

Step 7.

kmod**

Representative(climate class 3)

Ym

Step 8.
Calculation value strength

strength *[N / mm2][N / mm2]
Compressive strength

fc,o,k = 36

0.70 (short)

1,3***

fc,o,d = 22

Flexural strength aroundfm,y,k = 70

0.5 (permanent)

1,3***

fm,y,d = 27

fm,z,k = 70

0.70 (short)

1,3***

fm,z,d = 43y-axis
Flexural strength aroundz-axis302

※（Rijkswaterstaat, Central government 2018）233 頁より作成。
* According to NEN-EN338** According to NEN-EN 1995*** Associated with sawn timber according to NEN-EN 1995
11.6.9

Step 9: generate the marginal water level, wave height and wave period statistics

with Hydra-NL and determine the degree of mutual correlation.
The hydraulic load is a combination of decay and wave load. As discussed in detailin section 7.10.2, combined statistics cannot be derived for designs at this time. For
the time being, use should be made of the marginal statistics of the inland andinland water levels, the wave height and the wave period. In this step, the marginal
statistic for these parameters in the form of exceedance probability distributions isgenerated with the help of Hydra-NL.
Statistics outside water level
In paragraph 11.4 the exceedance probabilities of the external water level havealready been determined and are shown in Figure 86. In the illustration points of
all calculated water levels, wind directions appear to be west (270 °), west-south(247,5 °) and south-west (225 °), respectively approximately 30%, 25% and
15% contribute to the outcome. This means that these wind directions are
therefore dominant for the water level statistics in this export point.
Inland water level statistics
There is no inland water statistics for the small bowl the Whaa, so that a safe value
for the inland water level is assumed for determining the decay load. The winterlevel is assumed to be NAP-0.20m.
234 頁
Marginal statistics significant wave height and spectral wave period
In the same way as for the outside water level in section 11.4, the exceedance
frequencies for the significant wave height (Hs) and the spectral wave period (Tm) are generated with Hydra-NL and shown in Figure 99 and Figure 100.

1.0

303

※（Rijkswaterstaat, Central government 2018）234 頁より作成。
Figure 99 Excess frequency line significant wave height※（Rijkswaterstaat, Central government 2018）234 頁より作成。
Figure 100 Excess frequency line spectral wave period
For both Hs and Tm-1.0 it appears that in all illustration points wind direction
southwest (225 °) contributes about 90% to the outcome. Wind direction304southwest is therefore dominant for the wave load.
235 頁
Degree of correlation
To combine these parameters into the final hydraulic load, a degree of correlation
between the parameters has to be assumed. This cannot, as discussed in paragraph7.10.2.1, be determined in a model-based manner, but can only be estimated. For
the determination of the wave load, Hs and Tm-1.0 appear strongly correlated on thebasis of the above results; we keep full correlation here. From the above results also
seems to be a proper correlation between the wave parameters and the outside
water level. As described in section 7.10.2.1, it is sensible to assume full correlationin that case for combining the wave load and the expiry tax.
11.6.10 Step 10: Determine the calculation value of the tax effect on the Building Decree
The calculation value of the tax effect Ed consists of the combination of thecalculation value of the own weight load and hydraulic load. The hydraulic load in
this load situation is dominant over the own weight load, which means that only theload effect needs to be verified according to 6.10b from NEN-EN1990:

At which:
Gd

Calculation value of own weight tax

Sd

Calculation value of the hydraulic load at high water

KFI

Factor that in the case of the assessment in accordance with the Building
Decree depends on the chosen consequence class CC1, CC2 or CC3 andin case of verification in accordance with the Water Act is set equal to 1.0

YG

Partial factor for permanent loads

ξ

Reduction factor for unfavorable own weight tax

Gk

Characteristic value own weight tax

Arithmetic value hydraulic load (Sd)Since only the load effect according to 6.10b needs to be verified, the 'standard
method' for determining the calculation value of the hydraulic load according tosection 7.10.2 is applied.

305

V and H are strongly correlated:
P(V>Vd) = P(S>Sd)=Pdb
P(H>Hd)=P(S>Sd)=Pdb
Vd dominant
V and H are weakly correlated:
P(V>Vd) = P(S>Sd)=Pdb
P(H>Hd)=Φ(Φ-1(Pdb)・0,4)=Pndb

Hydraulic load dominant: 6.10b
Ed,b=KFI・YG・ξ・GK＋Sd

V and H are strongly correlated:See e.

Hd dominant
V and H are weakly correlated:
P(V>Vd) = Φ(Φ-1(Pdb)・0,4)=Pndb
P(H>Hd)=P(S>Sd)=Pdb※（Rijkswaterstaat, Central government 2018）235 頁より作成。
236 頁
At which:
Pdb = exceedance probability in case of dominant load
Pndb = exceedance probability in case of non-dominant load
In step 9 it was concluded that:

The wave load (H) and the decay load (V) are fully correlatedThe significant wave height (Hs) and the spectral wave period (Tm-1.0) are fully
correlated.

It follows that:

Exceedance of probability calculation value of decay load: P (V> Vd) = P (S>Sd) = Pdb



Exceeding probability calculation value wave load: P (H> Hd) = P (S> Sd) =PdbAbutting probability calculated value of significant wave height: P (Hs> Hs, d)= P (S> Sd) = Pdb



Exceedance probability calculation value spectral wave period: P (Tm-1.0> T m306

) = P (S> Sd) = Pdb

1.0, dThe decay load is determined by the inside and outside water level. Since theinland water level (hbi) is a deterministic variable in this example, the outdoor
water level applies: P (hbu> hbu, d) = P (V> Vd) = Pdb.
In accordance with Table 12 of Section 7.10.2.4, in case of a verification inaccordance with the Buildings Decree for CC3: Pdb = 1.0 ∙ 10-5 per year.
Using the marginal statistics from step 9, this results in the following calculation
values:Table 24: calculation values of wave parameters and water levels
Hs,d

1,40

m

Tm-1,0,d

4,12

s

hbu,d

+3,15

mNAP+

hbi

-0,20

mNAP+

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）236 頁より作成。
From this follows the calculation value of the decay load shown in Figure 101,
where for the specific weight of water a value of 10 kN / m³ is maintained.

©Rijkswaterstaat, Central government, Netherlands (2018)307

※（Rijkswaterstaat, Central government 2018）236 頁より作成。
Figure 101: Calculation value for the expiry tax when verifying Building Decree
237 頁
The wave load is determined with the model of Goda (for explanation see
Appendix D) and the results from Table 24. The normal of the artwork (θwall) has
an angle of 170 ° with respect to the north and the heavily dominant winddirection for the wave height (θwaves) turned out to have an angle of 225 ° to thenorth. The dominant angle of incidence for the wave load compared with thenormal of the artwork is therefore 55 °.
Table 25 Input model of Goda
SymbolVariable

Unit

BM

0,0

m

g

10,0

m/s2

hbu,d

+3,15

m+NAP

hdr

-3,00

m+NAP

hkr

+2,85

m+NAP

Hs,d

1,40

m

Tm-1,0,d

4,12

s

∆h

0,0

m

ƴw

1000

kN/m3

λ1

1,0

-

λ2

1,0

-

λ3

1,0

-

Ɵwall

170

°

Ɵwaves225°※（Rijkswaterstaat, Central government 2018）237 頁より作成。
Table 26: export model of Goda
SymbolVariable

unit

η

3,63

m

ω0

n.v.t. L determined by means of formula C1

s-1

d

6,15

m

h

6,15

m
308

Hd

3,08

m

k

n.v.t. L determined by means of formula C1

m-1

k0

n.v.t. L determined by means of formula C1

m-1

Tp

4,53

L

28,2

m

p1

16,00

kN/m2

p3

7,80

kN/m2

p4

n.v.t. because it concerns an overflow situation.

kN/m2

αimp0

0,50

-

αimp1

-0,0023-

αmpuls-0,0012

-

α1

0,667

-

α2

0

-

α3

0,485

-

α4

n.v.t. because it concerns an overflow situation.

-

-6,55

-

-2,52

-

-0,33

-

-0,51

-

1

2

11

22

※（Rijkswaterstaat, Central government 2018）237 頁より作成。
The calculation value of the wave load is shown in Figure 102.

309

238 頁©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）238 頁より作成。
Figure 102 Calculation value wave load on verification Building Decree
When the calculation values of the decay and wave load are combined, thecalculation value of the total hydraulic load in Figure 103 follows.

310

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）238 頁より作成。
Figure 103 Calculation value total hydraulic load on verification Building Decree
In the case, the horizontal beam at the height of NAP-1.00 m is verified, thecalculation value of the hydraulic load according to Figure 103 must be translated
into a distributed load p and spatial force F for the beam. The distributed load p isbased on the water pressure that the beam must withstand at a height of NAP1.00m, see Figure 104. As shown in Figure 104, the average calculation value of thehydraulic load is NAP-1, 00m equal to 43.8 kN / m2.(239 頁) The calculation valueof the resulting distributed load p on the beam is at a h.o.h. distance of 0.925
equals:From this follows a calculation value of the field moment due to the hydraulic load
for the beam equal to:

The axial force in the beam follows from:311

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）239 頁より作成。
Figure 104 Hydraulic load at the level of NAP-1.00 m
Calculation value own weight tax Gd
The cross-section of the horizontal beam is equal to:

The characteristic density of azobé (strength class D70) (Houtinfo.nl) ρk = 1000kg / m3 = 10.0 kN / m3. This results in a divided own weight load:
240 頁
312

From this follows a characteristic field moment due to the own weight load for the
beam equal to:

In accordance with formula 6.10b and Table 12 the calculation value for the field
momentum as a result of the own weight load follows:

Combine to total tax effect Ed
The load effect for the high water load situation is a combination of the hydraulicload and the own weight load. As mentioned, the verification in accordance with
NEN-EN 1995 consists of two prescribed unity checks, in which the tax effect isexpressed in three different terms, namely:The calculation value of the axial compressive stress due to the hydraulic load
(бc,0,d)The calculation value of the bending stress due to the own weight load (бm,y,d)

The calculation value of the bending stress due to the hydraulic load (бm,z,d)Arithmetic pressure load calculation value бc,0,d:

As calculated above N = 211 kN = 211,000 N.

Area A = b ∙ h = 300 ∙ 400 = 120,000 mm2

This results in an axial compressive stress of:

Calculation value bending load around the y-axis бm,y,d:

The calculation value of the bending stress in the outermost fiber around thez-axis follows fromMy,d = MG,d = 3.50 kNm = 3.50 ∙ 106 Nmm

Resistance moment around the y-axis:From this follows a bending stress equal to:313

Calculation value bending load around the z-axis бm,y,d:

The calculation value of the bending stress in the outermost fiber around thez-axis follows fromThe moment of resistance on the z-axis:From this follows a bending stress equal to:

11.6.11 Step 11: verification in accordance with the Building Decree
As mentioned in step 6, NEN-EN1995 provides two unity checks for theverification of the maximal absorbable tension of the beam, when subjected to load
according to Figure 96 (formulas 6.19 and 6.20):
241 頁

All calculation values of the strength and load terms are determined in steps: 7, 8, 9
and 10. From this follows:

The beam complies with a Building Decree verification with regard to the highwater load situation.
11.6.12 Step 12: Determine the calculation value of the tax effect on the Water Act
All actions to determine the calculation value of the tax effect in accordance with314

the Water Act are carried out in the same way as for the Building Decree in step
10. However, there is a different failure probability, so that the calculation value ofthe load effect with other calculation values of the outside water level, the wave
height, wave period and own weight load is determined.
The structural failure probability Peis,kunstwerk,CON is equal to 1 / 37,500 per year
(2,67E-5) in accordance with step 4.
Again, the standard method from section 7.10.2 is applied. In step 9 it was
concluded that:

The wave load (H) and the decay load (V) are fully correlatedThe significant wave height (Hs) and the spectral wave period (Tm-1.0) are fully
correlated.

Based on in step 10 it was concluded:


Exceedance of probability calculation value of decay load: P (V> Vd) = P (S>Sd) = Pdb



Exceeding probability calculation value wave load: P (H> Hd) = P (S> Sd) =PdbAbutting probability calculated value of significant wave height: P (Hs> Hs, d)= P (S> Sd) = Pdb



Exceedance probability calculation value spectral wave period: P (Tm-1.0> T m) = P (S> Sd) = Pdb

1.0, dThe decay load is determined by the inside and outside water level. Since theinland water level (hbi) is a deterministic variable in this example, the outdoor
water level applies: P (hbu> hbu, d) = P (V> Vd) = Pdb.
The constructive failure probability according to the Water Act must be describedin a reliability index:

Then, from Table 13 and Figure 37 in Section 7.10.2.5, the probability ofexceedance of the dominant tax Pdb = 7.0 ∙ 10-4 per year. From Table 13 and Figure
38 the load factor for the eigen weight tax YG = 1.10 follows. From Table 13 follows
315

KFI = 1.0 and ξ = 0.89.
242 頁
Using the exceedance frequency lines from step 9 and Pdb = 7.0 ∙ 10-4 per year, thefollowing parameters can be read:
Table 27 Calculation values of wave parameters and water levels when verifying according to
the Water Act
Hs,d1,08 m

Tm-1,0,d3,65 shbu,dNAP+2,6 m

hbi

NAP-0,20 m©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）242 頁より作成。
All hydraulic parameters in Table 27 and the load factor for the own weight tax
turn out to be less than derived from the verification in accordance with the
Buildings Decree in step 10. The calculation value of the tax effect according to theWater Act is therefore smaller than that of the Building Decree and therefore notnormative.
11.6.13 Step 13: verification in accordance with the Water Act
The calculation value of the tax effect according to the Water Act is smaller thanthat according to the Buildings Decree:
Since the calculation value of the strength Rd is the same for both verifications, theverification with regard to the Building Decree is dominant. This means that theverification of the high-water load situation with regard to the reliability
requirement in accordance with the Water Act for the horizontal beam at NAP1.00 meters can be terminated with regard to the absorbable bending stress. The
recordable shear stress and possibly also the stability of the beam still have to beverified for the high water load situation. The girder must then be checked forother load situations. In case these have already been done, other parts of the lockmust be verified.
11.7

References[Ref. 11.1]

CUR 197 - Rubble in practice Part 2: dimensioning of316

constructions in inland waters[Ref. 11.2]

Rijkswaterstaat (Directorate-General for Public Works andWater Management) WVL, Guide to assurance of reliability ofclosure in scenarios, Background report for the use of thescoring tables for the failure mechanism not to be closed,
November 2017, Definitive[Ref. 11.3]

Spreadsheet inflowing flow rate Dutch and Zeeland coast height,
Bob van Bree, October 2018

[Ref. 11.4]

Spreadsheet inflowing flow rate Vecht Delta, Bob van Bree,
October 2018317

243 頁

Terms and definitions
This section provides an overview of the most important terms and definitions as used inthis Work Guide. Where possible, reference is made to source documents in which
definitions are presented in order to prevent possible inconsistencies between the various
documents.
Water barriers and works of art

Weir
A flood defense is an artificial height (dike), natural height (dune) or high ground including
water-retaining components (for example works of art), or a succession of these, which has
the function of separating or turning water over a certain length and which is indicated in,for example, the shelf. A distinction is made between primary flood defense systems (mainflood defenses) and non-primary flood defense systems, including the regional water
defenses.

Artwork
A work of art in general is a civil engineering work for the infrastructure of roads, water,
railways, flood defense systems and / or pipes not intended for permanent human residence.

Water-resistant artwork
A water-retaining structure is a construction that forms part of a water-retaining structure
and over a limited length takes over the water-retaining function of the ground body, but
has been constructed for another (utilitarian) function that crosses the water-retaining
structure (such as fencing and drains, but also a passage for traffic - denomination). In
connection with this utilitarian function, these hydraulic structures are usually provided with
one or more movable closing means.

Wet Artwork
A wet work of art is a civil-construction construction that is part of a waterway or waterwaywith the aim of regulating the water levels, passage of ships, flood protection, crossing ofwaterways and / or drainage of water. A denomination therefore does not fall under a wet
work of art, but it does fall under a water-retaining artwork
318

Water-resistant object
A water retaining object is an object in or on the flood defense that takes care of the flood
defense function completely independently or in combination with other components thatform the barrier. A retaining wall (such as near Harlingen), a cofferdam or a quay wall
belong to this category

Non-water retaining object
A non-water retaining object is an object on or in the dike that does not make a positive
contribution to the flood defense function of the flood defense, or even has negative effects,
such as pipes, houses and trees.

Connection constructions
The entire transverse and local longitudinal profile of a ground construction in its deviating
form, at the transition to (in this case) the artwork.
244 頁
Reliability
In this working guide, the terms reliability requirement, limit state, limit state function,
failure / failure, reference period, design lifetime are frequently used. For the definition ofthese terms, reference is made to the Foundations for flood protection ([Ref 10.1]). Some
additional additions are made below.

Border condition
For the definitions of the different limit states (limit and serviceability limit state), reference
is made to the Accounting Principles.
Border states are assessed within the framework of the different design situations. These canhave to do with loss of balance, exceeding the (static) strength of the construction or thefoundation and fatigue. In addition to the normally present static and variable loads, special
design or load combinations (explosion, collision, etc.) must also be taken into account, witha relatively small chance of occurrence but with possibly considerable damage to thestructure. With these extraordinary loads one accepts more damage to the construction thanin the design situations for ordinary loads. Key concepts are resilience, prevention ofcontinued failure and residual strength with respect to the primary functions.
Furthermore, the Eurocode also knows the seismic load combination; however, this falls
319

outside the scope of this guideline.

Design life
The design service life is the period in which the construction or a construction component
is deemed to fulfill its function. The (economically) optimal design life does not have to be
the same for all parts of a construction. For example, the optimal design life span of amovement work will often be considerably shorter than that of a pile foundation.

Residual life
The period in which it is expected that an existing work of art will still be able to fulfill its(water retaining) function (from a certain reference point in time, for example a planned
inspection), is also called the residual life. By extending service life-extending maintenance,
the remaining service life can be increased.

Plan period
The plan period is the period that is considered in planning and plan development. The plan
period is not the same as a design life of a construction (component). For example, it canalready be foreseen in advance that extensions or modifications to constructions will be
required within the plan period.

Failure definition
In assessing the reliability of flood defenses, models are used. Because of the state of the art,
these do not always describe the entire process that leads to a flood. In that case, theultimate limit is not actually tested, but a situation that is still somewhat removed from it.
The description of this condition is also called the failure definition. For the failure
definitions related to the failure mechanisms of transfer and / or overflow, non-closure,piping and structural failure, reference is made to the WBI test track reports ([Ref 4.1], [Ref5.1], [Ref 6.1] and [Ref 7.1]).
245 頁
Water levels

Water level
Water level with respect to a reference level. In the Netherlands, the NAP (Normal
Amsterdam Level) is generally used for this purpose.

320

Water depth
Difference between water level and soil level.

ExpireWater level difference between indoor and outdoor level.

Atrial level
Water level inside in relation to the reference level.

Outside water level / outside level
Water level outside in relation to the reference level.

Target level bosom
Water level on which the underlying area is controlled. Since this is a target level, this does
not mean that the atrial level is a fixed water level. The water level in a chimney breast canfluctuate considerably, for example as a result of precipitation.

Maximum atrial level
Maximum permissible water level on the chimney breast (upper management limit).

Critical atrial level
Atrial level where no damage occurs in the hinterland.
Artwork related gauge

Threshold height
Height of the physical threshold of a work of art compared to the reference level. An
example is the top of the bottom construction of a lock.

Turning height reversing device
Top of the closed turning means of a work of art compared to the reference level.

Turning height - abutment
Top of the water retaining part of the artwork compared to the reference level.

Closing level
321

The level on the outside on which the artwork must be closed (variable of choice determines
the on-site operations).

Warning level
Low storm surge - limited mobilization (Definition according to Storm Surge Protection
Service SVSD).

Alarming level
High storm surge - full mobilization (approx. Once every 5 years, definition according to
Storm Surge Protection Service SVSD (now Water management center Nederland
WMCN)).
246 頁

Highest and lowest lock level
Highest and lowest water level at which a gun lock is still used.

Open Reverse heightSee definition in section 10.2.1.

322

247 頁Establishment and quality assurance
In 2003, the Technical Advisory Committee on Flood Defense published the Guideline for
Art Works 2003. This guideline has since been extensively used for the design andassessment of flood defense structures. Since 2003, knowledge and technologicaldevelopment has taken place and in 2017 the switch from exceedance probability to floodprobability standards has been made. This has made it necessary to update the Guidelines
for Art Works 2003.
In 2016, under supervision of Ton Vrouwenvelder and Jos Wessels (both TNO) andguidance from Arnaud Casteleijn and Ilka Tanczos (both RWS WVL), a set-up was made fora renewal of the Guidelines for Art Works 2003. In terms of content, the following persons
have contributed to this: Ton Vrouwenvelder (TNO), Ruben Jongejan (Jongejan RMC),
Raphael Steenbergen (TNO), Hans Niemeijer (Arcadis), Martin van der Meer (Fugro),Jentsje van der Meer (Van der Meer Consulting) and Bob van Bree (independent
consultant) ), Hessel Voortman (Arcadis), Bob Maaskant (HKV) and Alex Capel (Deltares).
Subsequently, two engineering firms (Royal HaskoningDHV and Movares), a contractor(Van Hattum and Blankevoort) and Rijkswaterstaat (Directorate-General for Public Works
and Water Management) applied the new guide to the same case. This did not lead to a
sufficiently unambiguous design. This has been a reason for Rijkswaterstaat (DirectorateGeneral for Public Works and Water Management) WVL to turn the guideline into aworking guide in which the emphasis has been placed on practical applicability: how can adesign be made given the current state of technology and the availability of instruments.
This working guide is written by Arnaud Casteleijn (RWS-WVL), Rob Delhez(Greenrivers), Ruben Jongejan (Jongejan RMC) and Bob van Bree (independent
consultant). Here, the results of the previous phases have been gratefully used. The chapter
Hydraulic loads has been reviewed by Alfons Smale (Deltares). The chapter 'Structural
failure' was realized in close collaboration with Raphaël Steenbergen (TNO Construction).
Bas Jonkman (TU Delft) has reviewed the Work Guide in its entirety. The Work Guide wasthen applied to the same case by three engineering firms: Lievense, Antea and Sweco. In
this case, however, an unambiguous design verification was achieved.

323

249 頁Appendix A
A.1

Process of 'Designing' incl. LCC

PrefaceA work of art is built for other reasons that turning water. Just when otherfunctions must be combined with water turning is a work of art. At the design is ofgreat importance to keep in mind from the start functions must be fulfilled by the
artwork. It has big advantages to it design process explicitly based on the functions.
A method to do that do is known under the name "Systems Engineering"(https://www.leidraadse.nl/). This appendix follow the principles of Systems
engineering as much as possible.

A.2

Structure of the design process
The following concepts are important:Operational concept: a description in ordinary language of the planned
operations with the artwork. Workable is a description of at most a few pages.
The operational concept is the starting point of the design process. The
description it is an important means of communication between the designer,
the future user and the client.

Function: a description of what the artwork has to do. Inside the operational
concept, the artwork must be able to do certain things (for example: turnwater, let ships pass).



Aspect: where the functions arise from the wishes and needs of the future user,
aspects arise from the fact that there is a work of art. Example: nobody will
want a work of art to do maintenance. Maintenance is however an important
aspect when designing a work of art. The same applies for example forlandscaping.

Requirement: a requirement sets a hard limit to a function or an aspect.
Example is one prescribed deflectable height: too low does not meet, too highdoes. For aspects: a manhole for maintenance has a minimum size of 1m at
1m. To small does not meet, too big does.

Assessment criterion42: not all aspects can be formulated in a requirement.
Business like Landscaping is often not provided with a hard rejection limit. In
the design choices such aspects are scored on a scale of worse to better (multicriteria analysis). Among other things, the aspects that apply within theframework of an EIA should be treated in such a way.
324

Technical solutions (or concepts): these are technical measures (variants) thatto fulfill the requested functions and meet the requirements.

Although structuring the design process is of great importance, it is also important
not to apply the above concepts too dogmatically. Furthermore, there is no one inpractice a continuous line from the operational concept to the technical solution. A
well-designed design process has an iterative character. Starting with a first one
sketch of the operational concept becomes a first set of functions and aspects
defined. From this follows a first set of requirements and assessment criteria. In
practice it turns out that with a set of requirements of 10 to 15 requirements thecore of the design problem can go well be covered. Such a small set of requirements
is workable when the concepts still have to be completed are being developed.
Developing technical solutions is to a large extent a creative process. It is
recommended to see the development of variants "separate" from the developmentof requirements.
______________________________
42

The international literature on systems engineering makes a distinction between"requirements" and "measures of effectiveness”______________________________(250 頁) The conscious development of solutions that apparently fall outside therequirements helps to either get the requirements sharp or to maximize thesolution space to make.

Finding is the process whereby developed variants are assessed on requirements
and assessment criteria and the remaining set of variants is further reduced to thefinal preferred variant. An important principle in funnel is the principle ofconsistent coarseness. In the early phases of the design, the process is dominated ofdefining and substantiated choosing (or rejecting) different variants. A very
detailed elaboration of all functions and aspects is not necessary, as long as thecomparison between variants is done fairly. Because the number of variants is large
at first is, a very comprehensive set of requirements and assessment criteria is evenundesirable because of this makes the design process uncontrollable and distracts
attention from the main issues.

Costs are generally treated as an assessment criterion (lower is better) but stand325

well apart from the other assessment criteria. By doing that you can make a tradeoff between an expensive variant with very good performance and a cheap variant
with only the minimum required properties.
As the design process progresses, the number of variants at the level of the artwork
itself becoming smaller (until eventually one). Similar considerations then become
made for parts of the object (for example, turning gear, movement work, energy
supply). This further elaboration is accompanied by the development of variants atpart level and the further detailing of the requirements to ultimately partial
specifications. With the exception of costs, assessment criteria often play a roleminor importance in the weighing of parts.
A final important element of structuring the process is stopping on time. A subspecification for the energy supply system is still meaningful; a partial specification
for a socket is not. With further detailing the number of requirements grows
explosively while the added value for the process.
Figure A. 1 shows the structure of the design process.

※（Rijkswaterstaat, Central government 2018）250 頁より作成。
Figure A. 1 Structure of the design process326251 頁
A.3

Design of water defense works

A.3.1

Operational concept and functions
The operational concept describes all operations that should be possible with theartwork to be. In the context of this Guideline, one of the functions will always beturning water. The operational concept should (roughly) indicate under which
circumstances the artwork is high-watering and under what circumstances not 43.
The operational concept is concise and described in natural language so that it is
the basis for a shared view of the object to be designed.
Also for the functions applies that they must all be described, including of course
the function water times. In many cases the design is determined by otherfunctions and is turning something "that comes with it".

A.3.2

Environmental analysis
The operational concept and the functions of the artwork come from what it workin the larger system. The environment in which the artwork stands however, often
has a dominant influence on the design. Analyze the environment of it artwork anddetermine which additional requirements and assessment criteria this imposes on it
artwork. "Environment" must be interpreted broadly. It concerns the physicalenvironment in which the artwork is realized, but also the administrativeenvironment. Consider, for example, integration in urban areas, accessibility of theartwork for breakdown repair, maintenance but also in emergencies.
If the artwork is part of a long transport corridor, the environment can be overhundreds of kilometers and the environment can even be cross-border.

A.3.3

Aspect analysis
Aspects are intrinsic properties of the system to be designed which, as a rule, do
not derive directly from a function to be fulfilled. An aspect analysis is analyzed
which aspects are important for the (continued) functioning of the artwork.
Examples of aspects are:•Design•Availability, reliability•

Maintainability•

Safety327

•Future stability•

Demolition•

Ambient nuisance•

Durability

Aspects concern the entire artwork and are not limited to the function of water
defense. Well the aspects of availability, reliability and maintainability are possible
significant influence on the function of water defense, especially on the failure
mechanism "not close".
A.3.4

Requirements
The operational concept, functions, environmental analysis and aspect analysis
lead to requirements to which the artwork must comply. A requirement is "hard"
and the evaluation or design it meets in principle with yes or no. To be able to dothat a requirement for an authentication method (calculation method), a variable
in which the performance of the artwork is expressed and a rejection limit.
______________________________
43

An example of this is the lock in Empel. It returns to "outside" about 50 weeks ayear (so it keeps the canal water in) and only returns the outside water of the Maas
for 2 weeks a year. Only turning the Meuse water falls under the Water Act andtherefore under this Guideline. Requirements must also be made for turning thecanal water, but these do not arise from the “turning outside water” function______________________________
252 頁
Requirements must be defined from the beginning of the design process. The
detail level of requirements increases as the design process progresses. The extent
of the requirement set will grow as the design process progresses.
Example of the development of a requirement at different stages of the design(no. refer to the phases of the design; explanation in italics)
The level of detail of the elaboration of the requirements varies from case tocase. A requirement is sooner detailed elaboration (and verified) when the riskthat does not become on further elaboration is bigger. That is the case when therequirement is very strict and / or the possibilities to meet the requirements.
The designer must at all times keep an eye on all requirements and per design328

step that evaluate requirements that determine the feasibility of the artwork. For
a As a flood defense, sometimes the flood defense requirements are crucial, butsometimes they are not.
1. Concept choice
Artwork must comply with the requirements of the Water Act (requirement israther coarse and still bad verifiable; in many cases, however, it is good tomake it plausible that the artwork can meet and the choice of concept isdetermined by other requirements).
2. Sketch design / preliminary design
The failure probability of the artwork for the aspect of water defense should besmaller than or equal to xxx per year. Concerns an overall probability of failure
for the object, derived from the location (dike section) and budgeting of the
failure probability within the process. The design team estimates thefeasibility of the requirement. When the requirement is relatively mild,
experience can be determined at this stage that can be fulfilled. In other cases,
an analysis can be done on some parts (such as reliability closure) arenecessary.
3. Definitive design / execution design
The artwork must meet the following task-setting failure probabilities:- Transshipment / overflow: xxxx per year
- Close reliability: xxxx per year
- Constructive reliability: xxxx per year ( alternative description: risk class xxxx
from Eurocode)
A.3.5

Assessment criteria
Like requirements, criteria also arise from the operational concept / function
analysis, aspect analysis and environmental analysis. A purely assessment criterion
differs substantially of a requirement. There is no rejection limit in a purely
assessment criterion. An assessment criterion is assessed on a continuous scalefrom bad to good. In English literature contains criteria known as "measure ofeffectiveness".
In practice there are many mixed forms of requirements and assessment criteria.
For instance in requirements regarding nature and environmental protection: the"soil" is formed by the legal requirements but a design that contributes positively to329

nature and the environment scores the criteria better.
Costs generally apply as an assessment criterion (cheaper is better), often in
combination with a requirement (task setting budget). It is preferable to the costs
to be treated separately from the other assessment criteria. This creates one clearer
image which provides an extra investment for the performance of the artwork.
253 頁
Practical example; storm surge in the mouth of the Göta Älv (or River of theGeats) (Sweden)
The city of Gothenburg in Sweden regularly suffers from flooding caused bystorm surges in the Kattegat. For this reason, the city of Gothenburgcommissioned a feasibility study in 2015 to a storm surge barrier in the mouth of
the Göta Älv (or River of the Geats). Special is that Stena Line with ferries andcruise ships moor in the city. The barrier must therefore be passable for this typeships (requirement). In the end, two variants remained:

A barrier divides into three openings with cylinder doors; the big ships canjoin good conditions and passing the barrier at low speed

A barrier in one opening, with floating sector doors; Two-way traffic is
possible with the largest ships

Both options meet the requirements, but it will be clear that the criterion"quality shipping passage "the second option clearly outperforms the first.
However, it also cost picture looks completely different. Mixing (adding) thesecriteria gives a diffuse picture where no clear preferred variant arises. When bothcriteria are separated held, it is immediately clear that a better nautical situationis possible at the expense of a (many) higher investment. The latter is a clear
choice about which a decision can be made by the authorized persons.

A.3.6

Variants
The development of variants is to a large extent a creative process anddistinguishes itself that respect of the formal and analytical process of requirement
analysis. It is therefore wise to see the development of variants separately from thedevelopment of requirements.

330

Variants begin coarse (main dimensions, number of individual openings, barriertype). On the roughly described variants takes place on a funnel, resulting in a
number of variants to lose weight. The remaining variants will be further detailed
and then re-evaluated choice takes place.
A.4

Verification of the design

A.4.1

Verification general
Verification is the process in which it is explicitly established or a (designed) object
meets the requirements set for it. To be able to carry out the verification is arequirement provided with a verification method and a measure of the performanceof the artwork with linked to a rejection limit. A verification method must be
appropriate for the requirement. Choosing an appropriate verification method is
the responsibility of the designer.
A work of art usually has to comply with several sets of regulations at the same time(for example the Water Act and the Building Decree). It is the responsibility of thedesigner to ensure that all requirements are verified. Combining / integrating
different sets of regulations is not necessary and can sometimes even lead to lack ofclarity and "missing" requirements. What is the best way to deal with combinationsof to deal with regulations is the responsibility of the designer.

A.4.2

Verification of flood defense requirements
This guide provides guidelines for the verification of requirements from the Water
Act the artwork will be asked. Other frameworks for verification are not consideredin this work guide. (254 頁) The designer is responsible for choosing appropriate
verification methods for the function of water defense.
Not all parts of a work of art fulfill a function when turning water. Ten For the
purposes of the verification, it must be made explicit which parts of the function
water defense systems are involved.
Parts that do not turn water can possibly cause damage if they fail water-retaining
components (e.g. bollards and fenders in a lock). The designer must explicitly
analyze such failure possibilities. Possibly such parts are still classified as part of
the flood defense.
331

The flood defense does not stop where the artwork stops. The connection to theenvironment makes part of the barrier and must be verified in the design.
A.5

Special topics

A.5.1

Judge
The manager must always be able to demonstrate that the artwork meets therequirements from the Water Act (duty of care). This is already taken into accountin the design, for example by making explicit which parts are part of the flood
defense and by to make water-retaining parts inspectable. Once every 12 years, theperformance of the flood defense system formally reported to parliament.
For new artworks, the design documentation must specify to which criteria theartwork must meet in order to comply with the flood defense requirements.
Employed assumptions are explicitly recorded so that it is easy to determine in the
management phase or circumstances have changed in an unfavorable sense.

A.5.2

Management and maintenanceManagement and maintenance is necessary to ensure that the artwork continues tocomply with the performance requirements. With the design of the artwork,
therefore, the maintenance strategy to be co-designed. When detailing
maintenance facilities designed in accordance with the maintenance strategy.
Special one attention is needed for the sometimes extremely high taxes that may
accompany maintenance operations. Consider, for example, the lifting of reversals;
the associated loads from the cranes must be able to pass through the construction
be included.
For new structures, management and maintenance must be included in the designby:•Determining the minimum quality criteria per component for each component
must comply.



Determining a maintenance concept for each component and associated with
it inspection and maintenance regime.

A.5.3

Reliability closure in the design332

The rail reliability closure differs from the track transfer and constructive collapse
because the performance is dependent on hard (technical) and soft(organizational) factors. The design therefore belongs to the design of artworks ofan operating regime, including mobilization, staffing, et cetera. This applies forboth regular use and operation as well as any backup measures and emergency
procedures. In a RAMS analysis all these aspects come together in one structured
analysis.
255 頁
As a rule, a work of art does not meet the requirements when it is first passed on,
but is adaptation of the design. The RAMS analysis iterates together with thedesign the final image and, like other parts of the draft dossier, goes from "gross tonice".
Measured technical measures (backup systems etc.) are clearly visible in the design
documentation. However, these measures go hand in hand with measures to betaken on the process side (operation). Often comes the detailed description of themobilization procedures and operation only later. It is therefore of great
importance to be in the draft documentation to establish which procedures arepresumed / agreed when making the design.
In practice, the reliability closure aspect appears to be the most conflicting issuedeliver between the function water defense and the other functions of the artwork.
Examples of the interaction between the function water barriers and otherfunctions•

A storm surge barrier has a barrier that rotates under water when it is open.
With In view of the safety of shipping, the defense is provided with an open
position in the open position latch. However, not being able to pull the bolt
leads to failure of the flood defense because it cannot be closed (action
taken for the benefit of one function leads to poorer performance of waterretaining).

•

With a view to water safety, it was decided to provide a lock with two heads
up to full turning height. Because always one of the heads is closed, thebarrier is always closed. However, the locked door can be hit upon whenlocking (extra failure mechanism) flood defense due to presence of the otherfunction).
333

•A discharge sluice must meet a strict requirement with regard to flood risk
management. To that reason a concept is chosen where the barrier, in caseof loss of the energy supply, automatically closes on its own weight.
However, this solution goes directly costs of the availability of the "drainage
of water" function (better performance as a barrier leads to worse
performance on another function).

257 頁

Appendix B

Standard failure probabilities

For reversals that are already regular from the primary function of the artwork
automatic opening and closing are possible failure processes such as alarm,
mobilization and operation not directly applicable. After all, the primary function
requires that the reversing means are closed from a different function than highwater times. Which means that in the case of a properly functioning work of art
these reversing means are closed as soon as the primary function is not exercised.
For such reversals are in the table below gives a number of failure probabilities,
which are largely based on conservative estimates. An actual substantiation ishardly or not at all available. The numbers are partly taken from the first version of
the Guideline Artworks (2003).
Turning means

Event

Failure rate per closing
question [1 / question]

Watergate

Movement work

10-4

Sand / dirt on the bottom

10-4

Obstruction on soil

10-4

Check valve

Reject closure

10-5

Wake-up door

Reject closure

10-5

Obstruction / sand / dirt

10-3

Movement work

10-4

Obstruction on soil

10-5

Butterfly valve

Do not close

10-5

Aggregate

Do not start

10-4

Sliding valve※（Rijkswaterstaat, Central government 2018）257 頁より作成。
334

The above numbers are a first indication of possible failure probabilities per closing
question. Before one of the above opportunities is applied, it should be considered
how real it is that one of the mentioned events occurs in the situation of the design
artwork.
Example: Sand / dirt on the floor near a floodgate can cause the floodgate does not close atall (door is blocked in his greenhouse) or that the lock gate does not closecompletely because sand / dirt does not stop the door can lower its threshold. In
the first case, there is a large one opening in the flood defense and this must be
taken into account at the remainder of the analysis (large flow opening). In thesecond case there will be there is only a gap, the flow opening is limited, and thisshould be taken into account in the remainder of the analysis. When theadministrator regularly inspects whether there is a question sand / dirt on thebottom or from the use data over several years that this never occurs, or that there
is no sand / dirt during inspections noted, this event does not have to be taken
into account at all are held. At a lock that the storm door turns into protective
process (several times a day), then it is very likely that sand / dirt on the bottom
will not be an issue.
259 頁

Appendix C Verification flood water situation with dominant own weight

In the exceptional situation that the own weight tax is very dominant compared tothe hydraulic load, the design must also be verified tax effect by means of 6.10a has
been determined. The criterion is that the own weight tax should be 80% or moreof the total tax.
In Figure 105 is again a translation of the prescribed exceedance probability of thecalculation value of the hydraulic load P (S> S d ) as prescribed exceedance
probabilities of the calculation values of decay and wave load P (V> V d ) and P(H> H d ) included, but now for the tax effect according to 6.10a.

335

V and H are strongly correlated:
P(V>Vd) = P(S>ψ0Sd)=Pdb(a)P(H>Hd)=P(S>ψ0Sd)=Pdb(a)Vd dominant

V and H are weakly correlated:
P(V>Vd) = P(S>ψ0Sd)=Pdb(a)P(H>Hd)=Φ(Φ-1(Pdb(a))・0,4)=Pndb(a)Own weight dominant:
6.10a Ed,a=KFI・γG・GK＋ψ0・Sd

V and H are strongly correlated:See a.

Hd dominant
V and H are weakly correlated:
P(V>Vd) = Φ(Φ-1(Pdb(a))・0,4)=Pndb(a)P(H>Hd)=P(S>ψ0Sd)=Pdb(a)※（Rijkswaterstaat, Central government 2018）259 頁より作成。
Figure 105: Exceeding probabilities calculation values of decay and wave load
according to 6.10a.
•

P db (a) = exceedance frequency in case of dominant load•

P ndb (a) = exceedance frequency in case of non-dominant load•

Quantification P db (a) and P ndb (a) according to Building Decree and Water Act:see the tables below.
With a verification according to 6.10a it is not possible to estimate in advancewhether the Building Decree or the Water Act is decisive for the tax effect Ed,a.
Both a verification of 6.10a according to the Building Decree and the Water Act
must be carried out.

Calculation value according to reliability requirement Building Decree
For the purposes of the verification of the Building Decree, the following table isused, in which the probability of exceeding the calculation value of the hydraulicloads (water level and wave height) must be taken into account from the 1-year tax
statistic in the last (mostly 100th) year of life, depending on the failure probability
βeis, BB (see paragraph 7.7.2).

336

Table 28 Calculation values hydraulic load Building decree
Consequence

βeis, BB for

P(S>Ψ0Sd)

Pndb(a) [-]class

reference period= Pdb(a)[-]Involvement

equal to lifetime

Involvementin 1-yearin 1-year

statistics instatistics inthe first year

the first yearof life

KFI*

ξ*

γG**

of lifeCC1

3.3

4.0∙10-2

2.4∙10-1

0.9

0.89

1.35 of 0.9**

CC2

3.8

1.0∙10-2

1.8∙10-1

1.0

0.89

1.35 of 0.9**

CC3

4.3

4.0∙10-3

1.4∙10-1

1.1

0.89

1.35 of 0.9**※（Rijkswaterstaat, Central government 2018）259 頁より作成。
Calibrated with consideration of Ψ0 = 0.6* Value in accordance with NEN-EN 1990 / NB** 1.35 in case of unfavorable working and 0.9 in case of a favorable working weight
260 頁
Calculation value according to failure probability Water Act
For the Water Act verification, the tax effect must be determined in 6.10a in the
1st year of life. The exceedance probabilities Pdb (a) and Pndb (a) are shown in Figure
105 and the other parameter values are shown in Table 29. P3 and P4 must
therefore be included in the tax statistics for the first year of life, depending on the
failure probability βeis, KW , CON (see paragraph 7.7.1), where:

Here is:βeis, KW , CON

Failure probability expresses in a reliability index for structural
failure and no failure by overflow / transshipment for a reference
period equal to tref = 1 year [-]. See section 7.7.1.

Φ-1 (...)

Inverse of the standard normal distribution

The parameter values for the own weight load are also included in Table 29.
Parameters

Values in 1st year of life

KFI

1,0

ξ

0,89

Ψ0

0,6
337

γG

See Figure 107

Pdb(a) en Pndb(a) [-]See Figure 106

Involve on 1-year statistics in thefirst year of life※（Rijkswaterstaat, Central government 2018）260 頁より作成。
Table 29: Recommended exceedances and parameter values according to 6.10a whenverifying Water Act
261 頁※（Rijkswaterstaat, Central government 2018）261 頁より作成。
Figure 106 Recommended exceedance probabilities decay and wave load Pdb(a) and Pndb(a)according to 6.10a on verification Water Act

338

262 頁※（Rijkswaterstaat, Central government 2018）262 頁より作成。
Figure 107 Recommended partial factor for self-weight tax for inspections based on the
Water Act in case of a dominant self-weight tax
263 頁

Appendix D Wave tax according to Goda's model
In determining the wave load, three types of waves are usually distinguished know
non-breaking, breaking and broken waves. There are many different ones for thismodels available that can translate one or more types of waves into one wave tax.
These models each have their own advantages and disadvantages. In this work
guide only the modified model of Goda is discussed.
Goda has a general formulation of the wave pressure on a caisson on a dumping
ground threshold. The equations of Goda apply to both non-breaking and breaking
waves. It should be noted that the model is in principle 'state of the art', but it isbased on curve fitting on the results of experiments. The formulation is through
Takahashi et al [Ref. 7.15] adapted to be used for waves that are against break the339

construction. Goda's comparisons are not only becoming worldwide used in thedesign of vertical breakwaters, but also for the design of flood defenses. Although
the comparisons are derived for breakwaters on a dumping ground threshold, they
are also widely used for walls without a threshold.
The equations do not change in case of transfer. The model of Goda is, however,unsuitable when large waves of waves are breaking at heavy waves occur in
combination with reversing means in a water-retaining structures. The model isdesigned for breakwaters, compared with reversing means relatively light. As ameasure of heavily breaking waves at retarders the ratio of significant wave height
and water depth at construction> 0.5 are used with a slope steeper than 1:50. Thissituation, however, is not very common in Dutch works of art. A second situation
where large wave impacts can occur is when the wall is irregularly shaped, so waves
can be 'trapped'. In this in cases, there is no question of a vertical wall and themodel of Goda cannot applied. This occurs, for example, with a slide that is in a
tube, or where a crossbar (top) protrudes. Such a projection can especially be large
wave impact loads if it is around the waterline. In that case, a numerical or physicalmodel to be used or other design choices to be made to prevent such peak loads. A
last case involving the use of the formula of Goda must be watched as the waves area double-headed wave spectrum show what can occur on the coast. This can be anapparently small one the immersion component make a major contribution to thewave force. When using the wave period T m-1,0 in the formula of Goda canunderestimate the maximum power to become. The period of the low-frequency
peak can be used as a safe assumption. Unfortunately, Hydra-NL does not provide
this information, so when this situation becomes a real risk Estimated, a numericalor physical model should be used.
Goda's model, moreover, seems somewhat conservative, which is not the case fordesigns problem. In Van der Meer et. al ([Ref.2.22]) becomes the formula of Goda
compared with testing. This showed that the formula averaged the maximum
power with 10% overestimated, with a spread (standard deviation) of 25%.
The modified model of Goda is also part of the WBI instruments and programmedin Risk, so that the use for designs fits well with future legal reviews.
This appendix deals with the application of the Goda model for the probabilistic
340

verification of the design, where the model is fed with calculation values. (264 頁)
For more detailed information about Goda's model referred to [Ref. 7.15].
Wave pressure distribution in calculation values
The wave pressure distribution according to the Goda model is included in Figure
108 together with some determining parameters. Only a few parameters are
discussed in detail in the text, while the rest are offered in Table 30 and Table 31,
where all variables used in the Goda model are explained.

©Rijkswaterstaat, Central government, Netherlands (2018)※（Rijkswaterstaat, Central government 2018）264 頁より作成。
Figure 108: Wave pressure figure according to the model of Goda
The pressure figure is composed by the values:

There is:341

In case hbu ≤ hdr:

In the case of hbu> hdr, the values of η, p1, p3 and p4 are calculated in the following
manner, including intermediate steps.
The modification factors λ1, λ2, λ3 depend on the construction shape of thewall. For a straight wall, all factors are equal to 1. In [Ref. 7.18] are some examples
for the values of λ1, λ2, λ3 for different construction types. For specific forms,
the modification factors can be determined with model research.
265 頁
Wavelength and wave period
The wavelength (L) can be iteratively determined in the following way:

At which:

With:
Tp

Peak period wave

T m-1,0Spectral wave period

The spectral wave period T m-1.0 follows from the hydraulic boundary conditions, forexample derived with Hydra-NL. In that case only the marginal statistic of T m-1.0 is
known and an estimate of the degree of correlation with the wave height, wave
direction and water level. This is discussed in sections 7.10.2.1 and 0.
The wavelength can also be accessed in the following way ([Ref 7.16] and [Ref7.17]):

342

Although equation C.1 is preferred, the error of the approximation is less than 1%.
Wave heightThe design wave height (H d) is derived from the significant wave height (H s ), of
which the marginal (but exclusively omnidirectional) statistic can be obtained with
Hydra- NL. The marginal statistic of the spectral wave height T m-1,0 can also be
used with Hydra-NL are determined. In the absence of information about therelationship between individual wave heights and For the time being, wave periods
are recommended to include the calculation values of H s and T m-1,0 determine thesame exceedance. The spectral wave period T m-1,0 eventually becomes used in
combination with the design wave height H d . For more information about theCorrelation between the wave height, wave direction and water level is referred toparagraphs 7.10.2.1 and 0.
As discussed in chapter 3 Hydraulic preconditions, it is possible are currently thehydraulic preconditions on the site of the design construction is not yet distracted
and one only has access to the preconditions on deep water (see Helpdesk Water).
In that case the significant wave height and the peak period at the site of a flood
defense using the Golf Tax Guide ports and protected areas [Ref. 7.21].
Depending on the bathymetry there can be phenomena such as shoaling, refraction
and diffraction. These influence the wave height. The effect is described with:
266 頁

With:
Hs

The significant wave height of the incoming wave just before theconstruction [m]343H s,0The significant wave height on deep water [m]Ks

The shoaling coefficient [-]Kr

The refraction coefficient [-]Kd

The diffraction coefficient [-]The first, very simple approach can be based on:

For the definitive calculation of the wave load, the various coefficients have to be
determined more accurately. The refraction and diffraction coefficients can be
determined using mathematical models. For further information, please refer toCollegehandleiding Windgolven (Wind waves college manual） [Ref. 7.16] andCollegehandleiding Korte golven (Guideline Short waves) [Ref. 7.17].
The design wave height (Hd) is chosen so that the exceedance probability of thisvalue during the storm peak is approximately 10%. For the average Dutch
conditions along the North Sea coast, on the Wadden Sea, on the Ijsselmeer and in
the river area, a safe value can be assumed, based on a Rayleigh distribution ofwave heights, of:

With:
Hd

Design wave height of the incoming wave just before the construction[m]

The design wave height can be physically limited by the water depth. In such a casethe wave breaks for the construction and the height is limited. For this reason, thefollowing applies:

With:
D0,5L

Water depth at approximately half wavelength (L / 2) for the construction
344

[m]
If this condition is not met, the design wave height of the incident wave for the
structure must be reduced to the maximum value according to formula C.2 above.
In the model of Goda the reflection coefficient does not occur. The model assumes
complete reflection. In the model, the wave height Hd of the incoming wave
(without reflection) has to be entered. The reflection is discounted in theexpressions for the wave pressures.
Wave pressure coefficient model of Goda345

267 頁

268 頁
Variables in Goda's model
Table 30: Input parameters model of Goda
SymbolVariable

Unit

BM

Berm widthmgGravitational acceleration (9.81 m / s2)

m/s2

346

hbu

Outside water level

m+NAP

hdr

Height of the bottom of the wall

m+NAP

hkr

Height of the top of the wall

m+NAP

HS

Significant wave heightm

Tp

Peak period waves∆hVertical distance between the bottom of the wall and themtoe of the dike / berm
γw
λ1
λ2
Ɵwall
ƟwavesVolumetric weight of water

kN/m3

Modification factor for the geometry of the wall-

Modification factor for the nature of the wall-

Angle between a line perpendicular to the turning means°

and the northAngle of wave fall in relation to the north°※（Rijkswaterstaat, Central government 2018）268 頁より作成。
Table 31: Output parameters model of Goda
SymbolVariableUnitηDistance between the highest point of the wave pressuremdistribution according to the Goda formula and the outside
water levelω0

Wave frequency on deep waters-1dVertical distance between the still water line and thembottom of the wallhVertical distance between the still water line and the toe ofmthe dike / berm
Hd

Calculation value of the wave height (without reflection)mkWave number

m-1

k0

Wave number on deep water

m-1

L

Wavelengthmp1

Wave pressure at the level of the still water line

kN/m2

p3

Wave pressure at the level of the bottom of the wall

kN/m2

347

p4

Wave pressure at the level of the top of the wall

kN/m2

αimp0

Factor for the effect of the threshold height

-

αimp1

Factor for the effect of the shape of the threshold-

αimpuls

Pulse wave pressure coefficient-

α１

Slowly varying pressure component-

α2Wave pressure component-

α3

Quotient of p3 and p1-

α4

Quotient of p4 and p1-

δ1

Coefficient 1 in the Goda formula-δ2

Coefficient 2 in the Goda formula-δ11

Coefficient 11 in the Goda formula-δ22

Coefficient 22 in the Goda formula-※（Rijkswaterstaat, Central government 2018）268 頁より作成。
269 頁

Appendix E Roadmap probabilistic verification of flood waterThis verification method is only explained to a limited extent for the high waterload, the roadmap is roughly outlined in Figure 109 and is very similar to the semiprobabilistic one variant in Figure 34. Instead of calculating with calculation values
and using a unity check verifies whether the design meets, is now explicitly withthe probability distributions of load and strength worked and a failure probability
verification done. In front of more information is referred to CUR190
Opportunities in civil engineering, part 1: probabilistic design in theory [Ref. 7.7]
and the TU Delft dictation Probabilistic Design [Ref. 7.8].
Step VII:

The hydraulic load (decay and wave load) must be used are madeof the correct hydraulic boundary conditions, see chapter 3
Hydraulic preconditions. In the event that waves play a roleplaying at the moment (2018) is almost impossible to playprobabilistic verification outside Risk to do. For the hydraulic tax
should be made use of the combined statistics of water level andwave conditions, which only in Risk is available. For the time
being, Riskeer ((Ring test) is a software application that supports348the WBI-2017 assessment) is only suitable for assessment and notdesign, because the program only has the tax statistics with yearof view 2023. In case there is no or limited waves can be expected
in extreme conditions and the hydraulic load so, due to decay tax
is dominated, outside of Riskeer probabilistic. With Hydra-NL inthat case for the export location near the artwork to be designed
the external water statistics are obtained, on which a probability
distribution can be fitted.

349

270 頁
A. Design verification procedure for the highwater load (probabilistic)

Step III: Determine the reliability requirementfrom the Building Decree:βeis,BB

Step IV: Determine reliability requirementfrom Water Act:Peis,KW,CON

StapV: collect the data from the construction component inthe (preliminary) design, needed for the strength calculation.
Step VI: choose the strength to be verified anddetermine the corresponding limit state function.
Step VII: Determine the joint probability density function of expired wave load. In

customize design dimensions

some cases, also determine the probability density function of the own weight.
StepVIII: Determine probability density functionof the strength of the structural component.

Step IX: Determine the probability density functions of the model
uncertainties for the strength and tax side.

Step X: Determine the chance of failure in aprobabilistic way: P(R ‹ E)

Step XI: Verification Building decision

through opportunities: P(R ‹ E) ≤ Peis,BB
Yes
Step XII: Verification Water Act throughDoes not sufficeopportunities: P(R ‹ E) ≤ Peis,KW, CON
Yes

Satisfies
Figure 109: Step-by-step probabilistic design verification A. for high water load※（Rijkswaterstaat, Central government 2018）270 頁より作成。

350