10th Asian Regional Conference of IAEG (2015)

Engineering Geological Asset Management for Large Dams
Yasuhito SASAKI(1)(1) Geology Research Team, Public Works Research Institute, Japan
E-mail:ya-sasa@pwri.go.jp
Abstract
Comprehensive inspection for asset management has recently started for almost all
infrastructures controlled by the Japanese Ministry of Land, Infrastructure, Transport andTourism (MLIT). The inspection has also proceeded for old large dams constructed before
30 years ago, which occupy about 45% of all large dams of MLIT. The temporal inspection
results revealed that 4 types of engineering geological problems have often occurred,
namely deformation of dam or its foundation (temporal occurrence rate; 27%), water
problems such as leakage, erosion and rise in uplift pressure (13%), deterioration in rockmaterials (20%), and slope movements or landslides near dams or reservoirs (37%). Though
the above occurrence rate is temporal one by the author’s experience, it suggests that thefoundations of dams and reservoirs also deteriorate. As these deteriorations proceed bygeological mechanisms, we have to detect the deterioration, clarify the mechanism, analyze
the deterioration speed and its influence to dam, and plan countermeasures by engineering
geologically effective methods. The above PDCA cycle is engineering geological asset
management (EGAM) and is challenging field for future engineering geology. In this paper,
the concept of EGAM is discussed with some inspection cases.
Keywords: large dam, asset management, deterioration, foundation, engineering geology
Introduction

2014 : 551dams
MLIT,JWA：121dams
Prefectures：430dams

30

600
Annual constructed dam (MLIT, JWA）
Annual constructed dams (Prefectures）

25

Over40years
25％
Over50 years
11％

400

1975

300

1965

10

200

5

100

0

1950

2.

500

Over 30years 1985
45％

20
15

Total

Fiscal year (April-)

Total number of Dams

Annual constructed dams

Asset management for the maintenance, longevity
and safety of old infrastructures becomes important
issue in the world. Especially, dam should be one of
the most long-lived and safe infrastructure. Then,comprehensive inspection for asset management has
recently started for large dams controlled by theJapanese Ministry of Land, Infrastructure, Transport
and Tourism (MLIT). The inspection has proceededfor old large dams constructed before 30 years ago.
Generally, dam is thought to be durable andengineering geological problems on foundations may
be few. But, after the above inspection, someengineering geological problems were found in many
dams. In this paper, such cases are introduced anddesirable procedure is proposed for engineering
geological asset management of large dams.

flood control are 551 dams in 2014 (Fig.1). 121
dams are directly controlled by MLIT and Japan
Water Agency (JWA) and Okinawa General Bureau(OGB). 430 dams are controlled by prefectures under
the support of MLIT. 45% of these dams are over 30
years after completion, 25% are over 40years and
11% are over 50 years.

S24
S25
S26
S27
S28
S29
S30
S31
S32
S33
S34
S35
S36
S37
S38
S39
S40
S41
S42
S43
S44
S45
S46
S47
S48
S49
S50
S51
S52
S53
S54
S55
S56
S57
S58
S59
S60
S61
S62
S63
H1
H2
H3
H4
H5
H6
H7
H8
H9
H10
H11
H12
H13
H14
H15
H16
H17
H18
H19
H20
H21
H22
H23
H24
H25
H26

1.

0

2014

Fig.1 Number of large dams for flood control inJapan

Outline of large dams for flood
control and the asset management
system in Japan

2.2 Asset management system of large dams in
Japan
MLIT prepared out a set of program for asset

2.1 Number of large dams
Number of large dams (over 15m in height) for1

10th Asian Regional Conference of IAEG (2015)

management for large dams as below.
a. Technical Criteria for River Works (volume of
Dam Maintenance), 2014. (TSDM)
b. Manual for Comprehensive Inspection of Dam,2013. (MCI)c. Manual for Periodical check for Dam, 2015
(draft) (MPI)
Technical Criteria for River Works is the mostcomprehensive standard for river works in Japan,
which contains not only river works but also slope
disaster prevention works and dam works etc. Volumeof dam maintenance (TSDM) is recently established,
it regulates general dam maintenance procedure. MCI
regulates comprehensive inspection of old dam after
constructed 30 years, the inspection will be
performed every 30 years. MPI regulates periodical
inspection, which will be performed every 3 years.
In addition, daily check, and urgent check after
earthquakes or floods are performed.

since trial run period. In this experience, 4 types ofengineering geological problems have often observedin old large dams, namely,
1) Small displacement of joint or cracks of dam
body or related facilities caused by the
deformation of dam bodies, facilities, or bythese foundations (occurrence rate; 27%)2) Water problems such as leakage, erosion andrise in uplift pressure (13%)3) Deterioration in rock materials (20%)4) Slope movements or landslides near dams orreservoirs (37%).
The above occurrence rates are based on temporal
data in my experience, more accurate data may be
published by MLIT in future.
（Dam system）（Dam body, foundation and the near slope）
Classification of dam body facilities and these importance level
Data formaintenance

Planning of inspection
Opinion andsuggestion by
specialist
Fundamental
investigation

Additional
investigation

Evaluation of soundness and draft
making of maintenance plan
Opinion andsuggestion by
specialist
Evaluation of soundness and making ofmaintenance plan
（Other facilities)
Maintenance plan of other facilities
such as electric facilities and machines

Fig.2 Inspection system of large dams for flood
control in Japan.

Comprehensive maintenance plan

2.3 Comprehensive inspection by MCI system
Comprehensive inspection of old dams based on
MCI system has formally started in 2014 after trial
run. The inspections on 7 dams have finished by
MLIT, JWA and OGB in 2014 fiscal year, and theinspections on 30 dams are now in practice.
MCI system is outlined as follows and Fig.3.
At first, every part facilities and structures of a
dam are classified three maintenance levels(importance levels). For example, dam body,foundation of dam, slopes near dam and landslidecountermeasure facilities are high level, and the lightof roadway of dam crest is low.
Treatment of maintenance is selected as Table 1,
namely final treatment is selected with the
combination of maintenance level and lank ofsoundness.

Fig.3 Flow of MCI system. (MLIT, 2013)
Table 1 Relationship between maintenance level,lank of soundness and treatment ofmaintenance, (MLIT, 2013)
Maintenance level of facilities (importance)

Lank of soundness

3.

Database

Engineering geological problemsof old damsHigh

MediumLow

a1 ○Need urgent measures

Preventive
maintenance,
urgent measure

Preventive
maintenance,
urgent measure

a2 ○Need prompt measures

Preventive
maintenance,
urgent measure

Preventive
maintenance,measureAfter the fact
maintenance,measureAfter the fact
maintenance,
priority
monitoring, or
measure○Need measures in nearb1 future

Preventive
maintenance,measurePreventive
maintenance,
priority
monitoring, or
measureAfter the fact
maintenance, or
no maintenanceb2 ○Need measures in future

Preventive
maintenance,
priority
monitoring, or
measurePreventive
maintenance,
monitoring

After the fact
maintenance, or
no maintenancePreventive
maintenance,
monitoring

Preventive
maintenance,
monitoring

After the fact
maintenance, or
no maintenance○No need measuresc ○Sound

The author has participated in the MCI system
making and inspections as engineering geologist

210th Asian Regional Conference of IAEG (2015)

4.

Case study

mass. It is generally difficult to find the leakage route.
Therefore, in this case, contour maps of ground watertable and its change in time series were checked
along the dam site and downstream to clarify
abnormal ground water table zone.

4.1 Deformation of dams or related facilities
Photo.1 is an open crack along a transverse jointof a gravity dam. This crack is thought to haveopened by a strong earthquake. This transverse joint
exists just on steep and partly over-hanged foundation.
Therefore, loosen rock mass, which has been formedby river erosion in long period, may affect theoccurrence of open crack. But it is generally difficult
to determine the cause. Therefore, in this case,drilling surveys and borehole observations were
performed to confirm the stability of foundation.
Photo.2 shows small displacement of a joint oftraining wall of stilling basin. In this case, it was
uncertain when and why the displacement has
occurred. Furthermore, there was no information of
the foundation. Then, some drilling investigation andthe monitoring of deformation by inclinometer andgroundwater table are performed.

Photo.3 Leakage water from dam
Photo.4 is the collapse of a weir (not large dam).
The weir was constructed about 80 years ago and thefoundation was partially river deposit, and the deposit
was eroded by flood stream or groundwater pressure.

Photo.1 Open crack along a transvers joint

Photo.4 Collapse of a weir by erosion of foundation
4.3 Low quality of rock and soil materials
Photo.5 is the deterioration of rip lap of a rock filldam. In this case, the cause is thought to be low
quality of rock material against freezing and thawing
because some rocks are porous and contain clay
minerals. But many rocks are sound, dam is totally
evaluated as sound.

Photo.2 Displacement of a joint of training wallof stilling basin
4.2 Problems on ground water and surface water
Photo.3 is leakage water from a retaining wall
which is located in the downstream of a dam. The
water passed under the dam foundation or right hand
rim grout line. The geology is the Tertiary volcanic
rocks, and there are many cooling joints in the rock

Photo.5 Deterioration of rip lap of rock fill dam
by freezing and thawing

3

10th Asian Regional Conference of IAEG (2015)

Photo.6 is a rock fill dam after repaired rip lap
rock material. The rock contains laumontite anddeteriorated by the repetition of dry and wet. Thisdam was covered with soil to prevent the repetition of
dry and wet for downstream side, and replaced withrocks of good quality for upper stream side.
Laumontite is also problematic for dam concrete.
Photo.7 and photo.8 is the case. The aggregate ismainly sandstone and contains laumontite in matrix.
In this case, deteriorated surface of dam concrete wasscraped and covered by 30cm thick of new concreteof good quality.

4.4 Slope movements, landslides
Photo.9 is a rock shed on a dam crest. Huge rockmasses distribute on slopes near the dam. Not only
dam managers but also visitors in sightseeing are
dangerous, then the dam office has constructed somecountermeasures such as shed, rock net, and rockanchor around the dam.

Photo.6 A rock fill dam after repaired laumontite
bearing rip lap rock. (Left photo is trench
investigation for checking deterioration.)

Photo.9 Rock shed on a dam crest
Photo.10 is a landslide block near the outlet ofarch dam. The management office of the dam in thephoto was constructed on the landslide, because this
district is very mountainous and there was no flat or
gentle slope near the dam except for the landslide. In
this case, monitoring of the landslide movement isperformed long time, the movement is very small.

Photo.7 Crack and pop up of dam concrete. (Theaggregate contains laumontite.)

Photo.10 Landslide near a dam
Photo.11 is a landslide near a reservoir. The
landslide topography is matured, therefore thelandslide is thought to have moved for long time
before the dam construction. The abutment
foundation of the road bridge is on the landslide, anddeformed several cm/year by landslide movement.

Photo.8 Repairing of dam concrete. (Same dam as
photo.7)4

10th Asian Regional Conference of IAEG (2015)

5.

Discussions

5.1 Engineering geological problems and necessary
technique
Table 2 shows the above engineering geologicalproblems in old dams, necessary techniques for asset
management and maintenance of them. Table 2 dares
to include ideal problems such as the displacement ofdams by active fault. There is no problem on thedisplacement of dams by active faults in Japanese
flood control dams.
The necessary techniques contain already using
techniques and developing techniques. It is importantfor engineering geology to develop the techniques.

Photo.11 Landslide near reservoir and a bridge on it.
4.5 Lack of geological data
Photo.12 is a very old dam. The construction has
started from 1941, stopped by World War Ⅱ, andcompleted in 1954. Therefore, geological data, maps
and documents are few, even foundation sketch data
does not exist. The lack of geological data has
become a big problem for administration because
weak serpentine widely distributes in this area and it
was impossible to estimate the stability of the dam.
Then drilling survey was conducted. Finally, thesurvey revealed that the foundation was notserpentine but tight and strong amphibolite rock.

5.2 Importance of engineering geological aspect inasset management
The above many cases suggest that thefoundations of dams and reservoirs also deteriorate,
deform and move in long time. Foundation asset
management (FAM) is very important. Unfortunately,
the concept of FAM is insufficient even in the MCI
system. As these deteriorations of foundations
proceed by geological mechanisms, engineering
geologists should improve the scheme of MCI.
Vessely (2011) published a technical reportsponsored by Federal Highway Administration(FHWA) in the USA on the concept of Geotechnical
Asset Management (GAM) for the maintenance ofgeotechnical structures of roads such as retaining wall,
embankment and slope disaster prevention facilities.
However, for the above purpose, not only
geotechnical aspect but also geological aspect areneed for the estimation of life cycle cost or longevity,
because the deterioration of geotechnical structures
proceeds with weathering and erosion of foundation.
Forecasting of these phenomena should be a task of

Photo.12 Old dam constructed before and after WorldWar Ⅱ.

Table 2 Engineering geological problems in old dams and future necessary techniqueEngineering geological problems in old dams
（Deformation of dam and foundation）
・ Displacement, open crack, subsidence deformation of
dam and related facilities caused by foundations（dambody and joint, spillway, training wall, footing, etc.）（Problems on ground water and surface water ）・Leakage water (Increase of leakage, Occurrence of
muddy water from drain hole under dam)・Increase in uplift pressure
・Erosion and piping of foundation（Low quality of rock and soil materials）
・Deterioration of rock materials （concrete aggregate, rip
lap rock of fill dam, etc.）
・Deterioration of dam materials or earth structures（by freezing and thawing, alkali aggregate reaction, etc.）（Slope movement, landslides）
・Landslides, rapid slope failures（dam slopes, cut slopes, banks, reservoir slopes）（Active fault）(There is no problem on the displacement of dam in Japanbecause all large dams have been avoided constructing on
active faults. )（Lack or insufficiency of information）
・Luck of geological data of foundation or monitoring data

5

Necessary technique・Investigation method to determine the cause of
deformation or displacement
・Evaluation method for stability of foundation
・Monitoring and forecasting of deformation inlong period
・Repairing method
・Investigation of groundwater flow
・Investigation to determine the cause of uplift・Evaluation of erosion resistance・Monitoring and forecasting of deterioration inlong period
・Repairing method
・Investigation method to determine the cause ofdeterioration
・Monitoring and forecasting of deterioration inlong period
・Repairing method
・Stability evaluation of reservoir landslide
・Forecasting destabilization by wave erosion
・Efficient monitoring
・Assessment of influence of rapid landslide・Countermeasure of rapid landslide・Distinguish method of active or non-active
・Evaluation method of activity in mountain area
・Assessment of influence of active fault
・Investigation of the foundation of old dams andreservoirs, and making these database10th Asian Regional Conference of IAEG (2015)engineering geologists.

Asset Management (EGAM) are proposed. To
progress EGAM, it is important to improve theprecision of engineering geological investigation andmonitoring, simulation and evaluation techniques onlong deterioration of foundations.

5.3 Procedure of engineering geological asset
management
Engineering geologists have to detect thedeterioration of foundations and its change, clarify
the mechanism, analyze and forecast the deterioration
speed and its influence to structures, and plancountermeasures by engineering geologicallyeffective methods. The above PDCA cycle is justEngineering Geological Asset Management (EGAM)
and is challenging issue for future engineering
geology.
For example, in the case that the deterioration of
a cut slope by weathering was found near a dam, we
have to investigate not only weathering depth and thestrength of deteriorated rock mass at present but also
estimate deterioration speed, slope stability in future,
influence for dam and the long-term effectiveness ofvarious countermeasures. After that, we have topropose the best countermeasure and its execution
time in the viewpoint of cost and safety. Especially, it
is important to estimate deterioration speed and thechange of stability in future, this will be a core
mission for engineering geologists.
Engineering geological investigation in theconstruction stage is mainly performed by direct
methods such as drilling surveys or edit tunnels toknow geology and engineering geological values.
But in the maintenance stage, we have to know
these changes for long period. It is a difficult task andneeds very precise investigations. Furthermore, thedirect methods are restricted because old structures
exist on the foundations and the structures are still
used.
Therefore, multiple investigation should become
more important, which consists of direct methods,
non-destructive methods such as geophysical survey,
field measurements and monitoring.
Conceptual flow of EGAM is shown in Fig.4. The
examples of technique contain not only commercial
techniques but also developing and conceptual
techniques. Engineering geologists should improvethese techniques and EGAM system to contribute to
make sustainable world.
5.

Flow of EGAM

Example of technique

Detectdeterioration

Investigation technique

Clarifymechanism
Analyze
speed andinfluence ofdeteriorationPlanmeasures・ Lidar, UAV or drone,
・ Multiple Geophysical prospecting
・ High quality core sampling and testing・ Borehole TV observation
・ Crack mapping by high resolution camera
・ Field measurements
・ Borehole measurements, etc.

Analyzing and simulating technique・ Database of deteriorated structures
・ Database of deterioration
・ Deterioration modeling・ Simulation of deterioration
・ Evaluation method of stability, etc.

Planning technique・ Menu of measures, new measures
・ Simulation of the effect of measures
・ Monitoring of the effect, etc

Fig.4 Conceptual flow of EGAM

Acknowledgements
The author is grateful to the members of dam
offices in MLIT and Prefectures reported above.
References
The Japanese Ministry of Land, Infrastructure,
Transport and Tourism (2013): Manual forcomprehensive inspection for dam, 112p.
The Japanese Ministry of Land, Infrastructure,
Transport and Tourism (2014): Technical criteria
for river works; practical guide for the maintenanceof dam, 67p.
Vessely,M (2013): Geotechnical asset management–implementation concept and strategies-,
No.FHWA-CFL/TD-13-003,62p.

Conclusions

Comprehensive inspection of old large dams has
started and revealed that 4 types of engineering
geological problems have often occurred, namely
deformation of dam or foundation (temporaloccurrence rate; 27%), water problems such asleakage, erosion and rise in uplift pressure (13%),deterioration in rock materials (20%), and slope
movements or landslides near dams or reservoirs(37%). To detect such problems and propose effective
measures, the concept of Engineering Geological6