Source: https://kupdf.net/download/uic-719-rpdf_5c8a5784e2b6f52b6568209a_pdf
Timestamp: 2020-01-23 19:22:03
Document Index: 578438299

Matched Legal Cases: ['art 1', 'art 2', 'art 3', 'art 2', 'art 5', 'art 7', 'art 10', 'art 12', 'art 1', 'art 2', 'art 1', 'art 2', 'art 3', 'art 4', 'art 5', 'art 6', 'art 8', 'art 9', 'art 12', 'art 13', 'art 14']

UIC 719 r.pdf - Free Download PDF
March 14, 2019 | Author: Ja Va | Category: Sand, Soil, Infrastructure, Civil Engineering, Materials
Download UIC 719 r.pdf...
Application: With effect from 1 February 2008 All members of the International Union of Railways Ra ilways
Terminology Terminology and classific classification ation of soils and subgrades subgrades ................ ......................... .................. ................ ....... 2 1.1 - Definitions.............. Definitions....................... .................. ................... ................... .................. ................... ................... .................. ................... ................... ............. 2 1.1.1 1.1.2 1.1.3 1.1.4 1.1.4 -
Geotechnical Geotechnical symbols, terms, definitions definitions and units .............. ..................... .............. ............... ............... ....... 2 Schematic cross section .............. ...................... ............... .............. ............... ............... .............. .............. .............. .............. ............ ..... 6 Geosynthetics Geosynthetics .............. ..................... ............... ............... .............. .............. .............. .............. .............. .............. ............... ............... .............. ....... 8 Maintena Maintenance nce of earth earthwork workss and track track bed on existing existing lines lines ...... .......... ....... ....... ........ ....... ....... ...... .. 8
1.2 - Geotechn Geotechnical ical classificati classification on of soils ................. ......................... ................ ................ ................. ................... ................... ............. 9 1.2.1 1.2.2 1.2.3 1.2.4 -
General ............. .................... ............... ............... .............. ............... ............... .............. .............. ............... ............... .............. ............... ............... ........... 9 Mineral soils ............. ..................... ............... .............. ............... ............... .............. .............. ............... ............... .............. ............... ............... ....... 10 Organic soils .............. ..................... ............... ............... .............. .............. .............. .............. .............. .............. .............. ............... ............... ....... 12 Mixture of mineral and organic soils ............... ...................... .............. ............... ............... .............. ............... ............. ..... 13
1.3 - Classification of subgrades subgrades according to bearing capacity..................... capacity ................................. ............ 14 1.3.1 - Soil quality quality classes............... classes...................... .............. .............. ............... ............... .............. .............. ............... ............... .............. ........... .... 14 1.3.2 - Bearing capacity classes for subgrade .............. ...................... ............... .............. ............... ................ ............... ......... 16
1.4 - Frost Frost susceptibil susceptibility ity of soils...................... soils............................... ................. ................ ................ ................ ................. ................. ............ 17 2-
Earthworks Earthworks and track bed for new lines .................. ............................ ................... .................. ................... ................... ......... 19 2.1 - Geotechn Geotechnical ical and hydrogeologi hydrogeological cal studies studies ............... ........................ .................. ................. ................ ................ ........ 19 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.1.6 -
General ............. .................... ............... ............... .............. ............... ............... .............. .............. ............... ............... .............. ............... ............... ....... Preliminary Preliminary studies........ studies............... .............. .............. .............. ............... ............... .............. .............. ............... ............... .............. ........... .... Main ground investigation investigation .............. ...................... ............... .............. .............. ............... ............... .............. ............... ............... ....... Supplementary Supplementary ground investigation......... investigation................. ............... .............. .............. ............... ............... .............. ........... .... Supervision Supervision of investigations investigations ............... ...................... .............. ............... ............... .............. ............... ............... .............. ........... Geological Geological and geotechnical geotechnical report ............. .................... .............. .............. .............. ............... ............... .............. ...........
2.2 - Suitability of soil for substructure works............................................. works....................... ....................................... ................. 23 2.2.1 - Body of the embankment embankment ............. ..................... ............... .............. ............... ............... .............. ............... ............... .............. ........... 23 2.2.2 - Prepared Prepared subgrade (embankments (embankments and cuttings)................. cuttings)........................ .............. ............... ............. ..... 23
2.3 - Design and construction of earthworks............................................................... 24 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 -
General ............................................................................................................ 24 Stability analysis of earthworks........................................................................ 24 Construction of embankments and prepared subgrades ................................. 25 Earthworks on highly compressible or expansive soils.................................... 26 Transitions between structures and earthworks .............................................. 28
2.4 - Composition and thickness of the track bed layers to give the desired bearing capacity............................................................................... 36 2.4.1 - Typical track bed construction ......................................................................... 36 2.4.2 - Determination of the thickness of the track bed layers to give the desired bearing capacity ............................................................................ 36
2.5 - Protection against frost....................................................................................... 38 2.5.1 - Track bed layers .............................................................................................. 38 2.5.2 - Parameters for determination of required depth of frost protection ................. 38 2.5.3 - Use of frost penetration depth chart................................................................. 38
2.6 - Properties of materials and construction of track bed layers.............................. 40 2.7 - Control of compaction......................................................................................... 42 2.8 - Drainage of subgrade......................................................................................... 42 2.8.1 - Ground water ................................................................................................... 42 2.8.2 - Surface water................................................................................................... 43
2.9 - Special construction methods and materials for new lines................................. 45 2.9.1 2.9.2 2.9.3 2.9.4 2.9.5 -
Treatment of soil stabilisation with binding agents........................................... 45 Track bed layers of limestone compacted with cement or bituminous layers .. 46 Asphalt coating ................................................................................................ 48 Concrete sub-ballast ........................................................................................ 48 Industrial by-products and recycled products .................................................. 48
2.10 -Ballastless track................................................................................................. 49 2.10.1 - Definition used in this paragraph ..................................................................... 49 2.10.2 - Interfaces between supporting structure and earth work ................................. 50
Maintenance of earthworks and track bed on existing lines ................................ 53 3.1 - General maintenance ......................................................................................... 53 3.2 - Maintenance of earthworks on existing lines...................................................... 53 3.2.1 - General remarks, inspection and day-to-day maintenance ............................ 53 3.2.2 - Geotechnical and hydrogeological investigation.............................................. 54 3.2.3 - Inventory of remedial measures (with comments) ........................................... 55
3.3 - Maintenance of track bed layers......................................................................... 56 3.3.1 - General ............................................................................................................ 3.3.2 - Determining factors.......................................................................................... 3.3.3 - Methodology of studies for maintenance of the track bed layers and subgrade ................................................................................................... 3.3.4 - Local repairs ....................................................................................................
3.4 - Vegetation control............................................................................................... 66 Appendix A - Example of method of investigation for the maintenance of track bed layers on SNCF...................................................................... 67 A.1 - "Track bed maintenance coefficient" k................................................................ 67 A.2 - Increase in the depth of the track bed layers required as a function of the value of the "track bed maintenance coefficient k" ................................... 68 A.3 - Methodology of studies of track bed layer maintenance on major lines (lines on which renewal is systematic)................................................................ 69 A.4 - Definition of the quality class of soils based on Standard NF P 11 300 ............. 72 Appendix B - Example of flow chart for subgrade improvement (DB and DR)............ 73 Appendix C - Example of rehabilitation of track beds SBB/CFF ................................... 75 C.1 - Typical track bed construction ............................................................................ 75 C.2 - Planning.............................................................................................................. 76 C.3 - Drainage ............................................................................................................. 78 C.4 - Repair methods for foundation layers................................................................. 79 Appendix D - Inventory of remedial measures................................................................ 82 D.1 - Soft ground ......................................................................................................... 82 D.2 - Rock slopes (natural or excavated) .................................................................... 92 D.3 - Voids and subsidence beneath the track.......................................................... 100 D.4 - Miscellaneous................................................................................................... 101 Appendix E - Example of methodology for bed layers design in existing lines (ADIF, Spain) ............................................................................................. 102 E.1 - Basis of design ................................................................................................. 102 E.2 - Evolution of the levelling operations with traffic................................................ 102 E.3 - Object of design................................................................................................ 102 E.4 - Application of Dormon’s law ............................................................................. 102 E.5 - Reference axle.................................................................................................. 103 E.6 - Characteristics of the track and bed layers....................................................... 103
1 - Terminology and classification of soils and subgrades 1.1 - Definitions 1.1.1 1.1.1.1 -
The geotechnical symbols used in this leaflet are listed in the table below; these symbols conform to the recommendations of the ISSMGE (see List of abbreviations - page 105). Other symbols and units used exceptionally by certain railways are given in the comments column. Table 1 : Geotechnical symbols
Table 1 : Geotechnical symbols
Dn, d n
Defined by: D60 /D10 ; d60 /d10
D 60 × D 10
a. Conventions adopted for the SI units: m, s, kg, N, N/m 2 (Pa) 1: for dimensionless values expressed as a r eal number (e.g. S r = 0,93) %: for the same values, which can also be expressed as % (e.g. S r = 93 %) -: for values which are defined as % (e.g. W L = 45)
Some terms are given below together with the most commonly used definitions and symbols. Table 2 : Terms and definitions
Table 2 : Terms and definitions
2 1----,---5-----r---Δσ ------ ( MN ⁄ m ) Δs
with: r : plate radius Δσ : increment of pressure under plate Δs : increment of settlement of plate
e r u t c u r t s r e p u S r o e m e r r u r u t o t f t c c u a u r l r t t p s s r b a r o f u n e S i d a r g b u S
Subgrade level Ballast Blanket layer Track-bed layers
Prepared subgrade or form layer Embankment or excavation surface Longitudinal drains
Fig. 1 - Schematic cross section
NB : Some countries include the blanket layer in the superstructure Track bed layers By virtue of their nature and thickness, the track bed layers play an important part in track performance with respect to track support stiffness, maintenance of track geometry and drainage. The general term "track bed layers" refers to both the ballast and sub-ballast layers. The design thickness of the track bed layers depends on: -
The thickness of the ballast layer should be taken into consideration when designing the blanket layer.
Ballast The ballast is considered to form part of the superstructure. For this reason, problems relating to the ballast layer and ballast materials are only referred to here in so far as they affect the quality of the infrastructure and track bed.
The blanket layer may consist of one or several layers (sub-ballast layer, frost protection layer, filtering layer). It may include granular, cement or lime treated layers, bituminous layers, geosynthetics or frost isolation plates.
Earthworks A general term applying to cuttings, embankments and composite cross sections.
Subgrade and platform The subgrade is the upper part of the earthworks, on which the blanket layer rests. On embankment, the subgrade will be formed of imported soil whereas in cutting it will be the naturally occurring soil or a layer of imported soil. The platform is the upper surface of the subgrade.
Prepared subgrade or form layer The upper part of the subgrade is formed into a prepared subgrade layer, which normally has a crossfall. The function of the prepared subgrade is considered differently by the different railways (e.g. bearing capacity, soil protection during the works and the whole life of the track, frost protection).
Longitudinal drains Longitudinal drains collect and discharge surface water, seepage water and ground water. Generally, a distinction is made between: -
Structural elements made of synthetic materials for use in earthworks and track bed constructions. A distinction is made between:
Geotextiles (see ERRI report D 117/RP 24) (see Bibliography - page 106) Geosynthetics (woven or non-woven) which may be used for: -
Geomembranes Geosynthetics (synthetic or bituminous layers) impermeable to water, which may be used for protection of sensitive subgrades against penetration of surface water or for protecting ground water against pollution.
Geogrids Fine or coarse mesh geosynthetics may be used for separation and reinforcement.
Geocomposites Compound structures made of at least 2 layers of geosynthetic materials.
Renewal Renewal is an operation in which one or several parts of the track bed are replaced.
Routine maintenance The term day-to-day maintenance refers to operations aimed at keeping the system in a state of repair compatible with service requirements.
1.2 - Geotechnical classification of soils 1.2.1 -
A mineral soil may be identified by its particle size distribution (PSD) curve which is obtained by sieving and/or sedimentation tests. Figure 2 - page 10 shows an example of a PSD curve. The ISSMFE advocates the use of the size limits given in table 3 - page 10. Some railways use slightly different limits. CLAY ) t h g i e 100 w 90 y 80 b ( g 70 n 60 i s s 50 a 40 p e 30 g a 20 t n 10 e c 0 r e P
0,002 0,006 0,02 0,06
100 90 80 70 60 50 40 30 20 10 0 0,002 0,005 0,02 0,05
Fig. 2 - Example of a particle size distribution curve (logarithmic scale of abscissas)
Table 3 : Particle sizes classification (according to EN ISO 14688-1: 2002) Soil fractions Very coarse soil
For the soil shown in Figure 2 - page 10, therefore: CU
d 60 -------d 10 2
d 60 × d10
1, 2 0, 06
2 ( 0, 3 ) 1, 2 × 0, 06
These are used in conjunction with the diagram derived from the Casagrande plasticity chart (Figure 3 - page 13), to give a further classification of the soil. Even a very small proportion by weight of organic material can affect the classification of fine soils according to the plasticity chart.
The sensitivity of a clay to water can be characterised by the Methylene blue test (blue value MBF). Similarly, the sensitivity of a soil to water can be characterised by the clay content (MB). When MB < 0,1, the soil is said to be insensitive to water; when MB > 0,2, the soil is sensitive to water.
1.2.2.4 -
High plasticity y a l C
60 ) % ( P
x e d n i y t i c i t s a l P
s l i o s c i n a g r o d n a t l i S
20 IP = 0,73 (wL - 20)
70 60 50 Liquid limit wL (%)
Fig. 3 - Plasticity chart for the classification of fine grained soils (after Casagrande)
Organic muds are organic soils deposited under water by sedimentation, and they originate from the decomposition of plant and animal matter and micro-organisms. They are often mixed with sand, clay or limestone and have an elastic, spongy texture.
NB : some railways use different values. Soils containing organic matter can also be classified according to plasticity using figure 3.
1.3 - Classification of subgrades according to bearing capacity To classify a subgrade, it is necessary to: -
Table 5 : Soil quality classes
Soil type (geotechnical classification) 0.1
Soft soils containing more than 15 % of finesa, with a high moisture content, unsuitable for compaction Thixotropic soils b (e.g. quick-clay)
Contaminated ground (e.g. industrial waste) Medium-organic soils b
High plasticity soils with more than 15 % of fines, collapsible soilsc or expansive soils d
Rocks which are very susceptible to weathering E.g.:
- Chalks with ρd < 1,7 t/m3 and high friabiity - Marl - Weathered shale 1.3
Soils containing more than 15 to 40 % of finesa (except for soils classified under 0.2 or 0.7)
Soft rock E.g.:
Microdeval wet (MDE) > 40 and Los Angeles (LA) > 40 Soils containing from 5 to 15 % of fines a except collapsible soils c
Well graded soils containing less than 5 % of finesa
Methods of classification used vary from one Railway to another. One of the methods is given in table 6. Table 6 : Determination of the bearing capacity of the subgrade
Embankment or excavation surface Quality class of the soil
1.4 - Frost susceptibility of soils Soils may be divided into three classes according to their degree of susceptibility to frost: -
A soil which is not susceptible to frost is one which does not cause unacceptable disturbance to the track geometry as it freezes and thaws. A soil which is susceptible or very susceptible to frost is one in which lenses of ice (formed under certain conditions of temperature and water availability) cause unacceptable disturbance of the track geometry. For individual gradings, the frost susceptibility of a soil can generally by deduced from its particle size using table 7. Table 7 : Frost susceptibility of the various soils types
Degree of frost susceptibility
In practice, it is essential to consider the overall grading. A soil composed mainly of coarse particles (which are unaffected by frost) will become frost-susceptible when the percentage of clay or silt rises above a certain critical level. It is therefore essential to use the concept of a critical percentage of fine particles. Casagrande's criterion is the best known; it gives the critical percentage of particles with a diameter of d < 0,02 mm (table 8) for soils having uniformity coefficients CU of 5 and 15 respectively. For other values of CU, the critical percentage may be found by interpolation. Table 8 : Critical percentage of fine particles (d < 0,02 mm) in a soil with regard to its frost susceptibility
Uniformity coefficient CU of the soil under consideration
fine medium coarse finemedium coarse ) t h 100 g i e 90 w 80 y b ( 70 g 60 n i s 50 s a p 40 e 30 g a t n 20 e 10 c r e 0 P
l e b i t p e l b i c e l e b p t i u s t l e e s b p c i s r y p t c e s u v e c e u s s s t s u n o
2 - Earthworks and track bed for new lines 2.1 - Geotechnical and hydrogeological studies 2.1.1 -
Table 9 : Geophysical methods
General methods Electrical
Table 10 : Mechanical methods
General methods Borehole
Mechanical Soils and rocks properties of soil Soils
Plate loading test Permeability tests
Mechanical Soils properties of soil Soils
Soils Rocks
NB : Requirements for performing most of the "in situ" tests indicated in the table are given in EN ISO 22476-1 to EN ISO 22476-6, EN ISO 22476-8, EN ISO 22476-9, EN ISO 22476-12 and EN ISO 22476-13 . Requirements for performing laboratory tests for soils of the type indicated in the table can be found in CEN ISO/TS 17892-5 (deformability). CEN ISO/TS 17892-7 to CEN ISO/IS 17892-10 (shear strength).
2.2 - Suitability of soil for substructure works 2.2.1 -
Body of the embankment
2.3 - Design and construction of earthworks 2.3.1 -
Where a soil susceptible to water or frost is used to form the body of an embankment, it should be protected by a covering of better quality soil. In areas susceptible to flooding, the sides of an embankment must be protected with a layer of rockfill or stones with an intermediate granular layer if required.
Cuttings: In ground which is sensitive to frost or water, cutting slopes should be protected by a coarse granular layer. The water can be eliminated by appropriate methods (toe drains, counterfort drains, ditches, filter layers, etc.). Other methods may also be used (surfacing of embankment, nailing, cantilevered or anchored retaining walls, etc.). Frost protection of cutting slopes shall be considered in cohesive soils in cold climate areas.
The degree of compaction and minimum deformation modulus, which are specified for each layer, are generally as follows:
Embankment fill: 95 % of the maximum dry density as determined from the reference compaction test (Standard Proctor test or Modified Proctor test depending on the type of line, high of the embankment and country)
EV2 /EV1
Often it is necessary to install a geogrid-reinforced soil body between the track bed layers and the pile like foundation system to have a good load distribution, load transmission into the piles and reduction of horizontal deformation.
2.3.4.2 -
8 Protective layer 9 Drainage layer 10 Section through embankment or
Top of rail 20 cm sub-ballast 50 cm foundation layer
11 Weephole 12 Foundation construction depth 13 Concrete fill
EV2 ≥ 80 MN/m2 EV2 ≥ 45 MN/m2 Backfill compacted in 15 to 30 cm thick (layers CU ≥ 5) Fig. 6 - MAV example
Embankment construction after the bridge L ≥ 20 m I = H: 1 ≥ 8 m ≥3m x
m a 1 5 %
A B C D E F G I Hr Hr
Bituminous concrete subballast Strongly compacted layer Md ≥ 800 Kg/cmq ; ds ≥ 98 % AASHTO mod ; CBR ≥ 50 Embankment Md ≥ 400 Kg/cm² ; ds ≥ 95 % AASHTO mod Alternate layers of cemented mixed and strongly compacted earth (thickness: 20 cm per layer) Layers of cemented mixed (thickness: 20 cm per layer) Layers of granulated mixed strongly compacted ds = 98 % ; Md ≥ 800 Kg/cm² ; CBR ≥ 50 ; max 30 cm Loose granulated mixed, A1 - A3 Drenaige = H if H ≤ 4 m = 3 m if H > 4 m
Zone de transition (schéma) H ou 5 m mini Sous couche traitée à 3 % de ciment sous couche couche de forme
m 0 5 , 0
lD= 0,85 100 % PS sandy gravel l = 0,80 crushed gravel D
Fig. 13 - ZSR (Slovakia)
When the structure abutment is not perpendicular to the track axle, the solution indicated schematically in the plan view on fig 14 can be adopted.
2.4 - Composition and thickness of the track bed layers to give the desired bearing capacity 2.4.1 -
Typical track bed construction
e=E+a+b +c+d+f (e in metres) Ballast e
Blanket layer Subgrade
=0 2, 50 -----L-= --------------- – 2
when the nominal maximum axleload of hauled vehicles does not exceed 200 kN (seeUIC Leaflet 700)
when the nominal maximum axleload of hauled vehicles does not exceed 225 kN (seeUIC Leaflet 700) when the nominal maximum axleload of hauled vehicles does not exceed 250 kN (seeUIC Leaflets 700 and 724)
2.5 - Protection against frost If a subgrade is frost-susceptible, frost must be prevented from penetrating down to it, especially w hen hydrogeological conditions are unfavourable.
The materials used for track bed layers must not be susceptible to frost and thus satisfy the conditi ons described in point 1.4 - page 17. The adverse effect of frost on the subgrade can be countered by increasing the overall thickness of the bearing layers or by adding a prepared subgrade made up of soils not susceptible to frost. The total thickness of the track bed layers is first calculated according to the bearing capacity of the subgrade (see point 2.4 - page 36). The depth of construction must then be increased as necessary to give the desired protection over frost-susceptible soils.
0 °C hb
) m ( n o i t c e t o r p t s o r f f o h t p e d d e r i u q e R
1 600 1 200 Frost index (degree days)
3 Average annual temperature
Fig. 16 - Required depth of frost protection
When the average temperature is below 0ºC the insulating effect of the snow is taken into consideration by national directions
2.6 - Properties of materials and construction of track bed layers Ballast: Ballast is formed from crushed stone and consists of particles in the size range 20 to 63 mm, characteristics of aggregates for use as ballast material may be found in EN 13450:2000/AC 2004 (see Bibliography - page 106). No further details of ballast are given in this leaflet.
Sandy gravel for the blanket layer: Procedures to determine the characteristics of aggregates susceptible to be used for blanket layer may be found in EN 13242:2002/AC 2004 and EN 933-1 to 933-9. Text for thermal and weathering properties of aggregates are given in EN 1367-1 to 1367-5 (see Bibliography - page 106). Where a sandy gravel is placed directly in contact with the ballast, it must be well-graded, as indicated in point 1.2.2.1 - page 10, and the materials used should be sufficiently durable, e.g.: -
Some railways fix a maximum value of permeability to limit the water inflow to the subgrade (e.g. k ≤ 10-6m/s for the required density) and define a minimum crossfall of the subgrade. The crossfall should be in the range 3 % to 5 % (2,5 % for ballastless track over cement treated embankments and cuttings).
NB : It is necessary to ensure: -
γd ≥ 100 - 103 % of the Normal Proctor density or γd ≥ 98 - 100 % of the Modified Proctor density
depending on the country -
Some countries include EV2 /EV1 ≤ 2,2 for EV1 less than the minimum value prescribed for EV2.
E V2 (MPa)
2.7 - Control of compaction The compactness of an earthwork and track bed must be monitored. It is usual to control the density and the deformation modulus. Concerning density, either nuclear or traditional methods may be used. At present the deformation modulus can be monitored by means of the plate load bearing test. When plate load bearing test is used, the load interval for the estimation of Ev might be 0,3 - 0,7 of the maximum load. This maximum load depends on the plate diameter (0,5 MN/m2 for the 300 mm plate and 0,25 MN/m2 for the 600 mm plate may be used). This test is strictly intermittent in nature. Some railways are trying out continuous longitudinal or surface monitoring methods using dynamic devices: -
2.8 - Drainage of subgrade 2.8.1 -
Any rainwater falling on the surface and likely to penetrate to the subgrade must be quickly evacuated. This requires:
2.8.2.1 - Correct crossfall of the subgrade towards the longitudinal drainage system (cuttings) or towards the shoulder (embankment) in both straight and curved track. The crossfall should be in the range 3 % to 5 % (2,5 % for ballastless track over cement treated embankments and cuttings). However, in canted sections, the subgrade for double-track lines may be designed with a single continuous crossfall. The top of the blanket layer must also have a crossfall, as was mentioned above. Provided that the blanket layer is well-graded and well compacted (see point 2.6 - page 40), about 80-85 % of rain water (run-off coefficient c ≈ 0,80-0,85) runs away directly from the ballast/blanket-layer interface to the drainage system. The remaining runs into the blanket layer, whose rapid drainage is also facilitated by the crossfall of the subgrade. Some countries use high permeability blanket layers with run-off coefficients up to 0,1 for high permeability non water sensitive natural soils, so drainage could not be necessary.
2.8.2.2 - Correct dimensioning of the components of the lineside drainage system. These must be capable of accommodating the run-off produced during the design storm corresponding to the return period (at least ten years): -
a) Calculation of run-off coefficient QP This flow can be calculated by the following formula: QP
v u --
K ⋅ i ⋅ c ⋅ A
b) Calculation of run-off coefficient Q V The run-off coefficient is calculated according to: -
Charts may be compiled to determine the run-off for regions where there is a considerable difference in rainfall patterns. Examples are given in ERRI D 117/RP 13. Nevertheless, these calculations should be reviewed according to the national codes of practice.
2.8.2.3 - correct design of the filtering materials placed directly against the longitudinal drainage system. The main rules to be observed in this respect are the following: -
fine medium coarsefine medium coarse fine medium coarse ) t h g i e w y b ( g n i s s a p e g a t n e c r e P
2.9 - Special construction methods and materials for new lines In addition to the construction methods and materials described in the preceding points of this leaflet, there are special methods and materials which may be considered in certain circumstances. In the following pages, only those methods and materials are presented, for which sufficient experience is available.
This treatment consist on mixing "in situ" clayey soils with lime (CaO or Ca(OH)2) in order to improve the geotechnic behaviour, workability and to decrease the water content of the material to be used on the foundation, core or top of the embankment and in the bottom of cuttings. The layer treated with lime might be protected by a sufficiently impermeable sub-ballast layer or by surface treatment with bitumen in order to prevent the lime from being washed out by rain water sealing the drainage system.
2.9.1.2 -
The FS has had good experience with two methods for more than 20 years.
90 ) t h g i e w y b ( g n i s s a p e g a t n e c r e P
8 13 19 32 Particle size d (mm)
Fig. 19 - Grading envelope for asphalt conglomerate
FS (Italy) has decided to provide all its new lines, including high-speed lines, with a bituminous mix sub-ballast layer, placing a 12 cm sub-layer of bituminous mix under the ballast, both in embankments and cuttings - in order to distribute the loads and protect the soil in embankments from water infiltration. The advantages of using the bituminous sub-ballast are: -
70 (1/10 mm)
Fig. 20 - Comparation of permanent way systems
According to the project team for UIC I/03/U/283 ballastless track project, the ballastless track system on earthwork can generally be separated in 3-subsystems: -
For dimensioning the supporting structure it is necessary to have the deformation modulus of the earth work. Information about measurement of deformation modulus and about relations with bearing capacity and compaction can be found in point 2.3.3 - page 25. Example of load criteria: DB requires for slab track system in lines with speed > 230 km/h an Ev2 = 120 MN/m2 for the earth work under hydraulically bonded layer.
2.10.2.2 -
Fig. 21 - Settlements of embankments
Settlement predictions shall show, not only how fast construction is to proceed, but also demonstrate that any settlements, which occur after the line is opened, can be rectified according to adjustable fastening capacity or other technical method.
When settlement criteria cannot be achieved, the use of ballasted track or a special design (on pile foundation for example) must be chosen. In the last case, the rules for ballastless track on bridges may be applied.
2.10.2.3 -
For plain track the supporting structure is considered as continuously supported with enough contact area and no particular device is required for transmission of horizontal forces. However particular design or devices are required when the continuity of supporting structure is stopped to limit the longitudinal displacement induced by thermal expansion.
2.10.2.4 -
3 - Maintenance of earthworks and track bed on existing lines 3.1 - General maintenance The organisation of maintenance on any given line must be optimised with regard to the technical (safety and comfort) and economic aspects. General maintenance work involves: -
3.2 - Maintenance of earthworks on existing lines 3.2.1 -
General remarks, inspection and day-to-day maintenance
NB : serious problems may sometimes occur without any previous detectable signs. 3.2.1.2 -
3.3 - Maintenance of track bed layers 3.3.1 -
When the ballast is renewed, care must be taken to ensure, of course, that the layer between the ballast and the subgrade is kept intact and not rendered dangerously thin or even removed altogether.
1 1 Traces of lines in ballast 2 Base of excavation 3 New drain required
Fig. 23 - Manual cleaning of ballast between sleepers
If necessary, geotextiles can be placed vertically between the tracks to protect the renewed ballast from the polluted ballast on the adjacent track.
3.3.2.3 -
When the level of stress is "acceptable", i.e. when the ballast + blanket thickness is at least equal to the values given in point 2.4.2 - page 36, a marked deformation of the subgrade through the effects of traffic is not likely to occur (provided the rules on filtering and correct hydraulic behaviour referred to in points 3.3.2.1 - page 57 and 3.3.2.2 - page 57 have been observed). Point A.2 - page 68 describes a method developed by the SNCF for evaluating the increase in thickness of the track bed layers required according to the "maintenance coefficient" defined in point A.1 - page 67. Appendix E - page 102 describes a method incorporated by ADIF.
3.3.2.5 -
Precise statistical data on the frequency of lifting work together with on-site observations regarding slurry patches, work on the drainage system, etc., will provide the detailed information required to determine what form of day-to-day maintenance is required. The scientific approach used on the SNCF in the assessment of maintenance requirements of the track bed and subgrade has been developed on this basis. It is described in point A.3 - page 69.
Generally, railways undertake systematic geotechnical investigations to determine the maintenance requirements of the subgrade and track bed layers. Examples of this type of approach are given in Appendices B - page 73 (DB and DR) and C - page 75 (SBB/CFF).
3.3.3.3 -
The methodology used for establishing the thicknesses of the bed layers (ballast + subballast) is based upon the concept of settlement-conservation coefficient and upon Dormon's law (Question ORE D 117, Rep. 28) which have been used to define the thicknesses given in point2.4.2 - page 36. An example of methodology for bed layers design in existing lines is given in Appendix F (ADIF, Spain).
Several methods for improving bearing capacity are listed below, with comments:
Increasing the thickness of the blanket layer during renewal Track renewal is carried out as follows: -
If these measures are to be lasting, they must be accompanied by repair work to the longitudinal drains or by the building of such drains if they do not already exist (see point 2.8 - page 42).
Complete substitution of the track bed layers Several techniques can be used: -
Fig. 24 - Enhancement of bearing capacity recommended. Model of solution by geocells slab (ZSR)
Geocomposites for improving the bearing capacity consists on a reinforcement component (for example geogrid) and a filter component (a geotextile). They can be used in or beneath the blanket layer (including the formation layer) or at the subgrade. Geocomposites improve the load distribution. Therefore it is possible to reduce the thickness of the blanket layer and/or formation layer. For example, the regulations of the DB AG (Ril 836) permit reduce the thickness of the blanket layer 10 cm, if a geocomposite is used. These materials should be selected taking into account the long time behaviour of their properties.
NB : The use of subgrade improvement methods on existing lines is described in UIC Leaflet 722 (see Bibliography - page 106).
The design of trackside drainage systems is given in point 2.8 - page 42.
3.3.4.3 -
2 Extruded polystyrene foam insulation layer 3 Sandy gravel
1 °C 5 °C 0,80 ) m m (
h r e y a l n o i t c e t o r p t s o r f f o s s e n k c i h T
hi = 100 mm -1 °C 2 °C -0,5 °C
0,40 5 °C
0,20 4 °C
1 000 1 500 500 Frost index in degree days
Fig. 25 - Required thickness h s of sandy gravel frost protection layer as a function of the frost index and the average annual temperature for the reference year for different thicknesses h i of extruded polystyrene foam
3.4 - Vegetation control Environmental protection considerations prompted the railways to review current policies concerning the use of herbicides for vegetation control. This is not just a problem which affects the ballast, but extends to side paths, slopes and drainage systems. For reasons of operating safety and maintenance costs, vegetation growth must be controlled at regular intervals, at least on lines with heavy traffic. Proper drainage of the sub-ballast layers and prepared subgrade is an important pre-requisite for creating conditions which are hostile to the growth of vegetation. Herbicides must be used in minimum dosages, the weather conditions must be suitable (as far as possible: work in daytime, absence of wind and rain). The herbicides must have been tested and approved by the relevant authorities. Additional restrictions may govern the use of herbicides in special areas and for protection of the water table. When, by suitable measures (regular cutting, for example), vegetation is limited to grass only in a strip of about 3 m to either side of the track, the growth of vegetation towards the track can be reduced. The growth of vegetation can also be hindered by reducing the supply of nutrients near the track. The growth of vegetation in the track itself can be reduced by the installation of an asphalt layer under the ballast and on the side paths.
10 k=4 k=3 Is 5
Appendices The representative curves depend on the traffic carried on the lines (classified according to UIC Leaflet 714) (see Bibliography - page 106), on the maximum nominal axle load for hauled vehicles and the characteristics of the track subgrade. It is possible to reduce the value of k by increasing the thickness of the track bed layers (by raising the track, for example) as shown in the example of figure 29. Variation in depth (m) 0,50 0,40
B2s B.C. Hydro. Clean and well graded Very hard
The quality class corresponds to a ratio of 0/50 0/50 ratio of class QS0 w ≥ 1,25 wopn
c i f f a r T
h / m k 0 6 1 ≤
v < 0 2 1 c
d - / t / d 0 0 - t 0 0 0 0 0 0 0 0 0 0 0 2 3 0 0 2 > < 6 > <
d / t 0 0 0 6
A n o i t a c i f i s s a l C
h / m k 0 h 2 / 1 m k ≤ v 0 8 < ≤ 0 v 8
c e B h t b 3 C h ? N s g i l n b i c r A a e t b b s w A B 2 e o d a a a l A B C o e h t y t b b p n t e m Y i s o n d c a t l o i l n t 0 d a e c 2 e t b e b n n l i s t a ? s h e a s s m a t h l n r t s l e o o o a r i s n r t I c b o c Y e d m s e 6 i y k f i c b c a e d r p e t s d g e e e n h o t c l s x n I e i
c c B C b b b A B C a a a A B C
o t y r a s ? s e e c c n e e a n n t s e i a t e n s r i a c a n m W i 1
r e e t , r y d a a a d t n h l e n e i o t c 1 t o t e m a m t a k e i n l w s k l k n b n o n r g a l a o m i o l t f i a o r s o o b w n s r e t s b l l i h e a a f e m t a e u h t d v e i s n q i t u e a e d t h i v h e i t h o s m w m d m t e o d r e l t d e r e k d o f r n c s u o n o n d r a e e t c t u t r i i . h c 2 e i o e c v c e d u d r o i f d e r e a f a q e d a y r e e b e n , a g r i h d t n l e d t e a b l t s o f t n s u d h 1 s s e a t o c n c u k s a r n e o r k e c n f n e o h w o l o e h a i w b t d 2 c h t t h h t i a e d a e s c t i n h n e h e m r a o h a f a T a I n w u r l q f w e o p x X E X X
y t i c C m r X o f 5 i n u c f ) B 2 o b X N t ( C X n e 3 d e i a c c r i A f X f g b b b e A B X o u a a a 2 c s ? A B C e e 3 h > h t t s f I o U x 2 Y 5 1 e ) Y v 1 o i t s . . e b c h a c ? o T a d c e n 6 v n 9 o r i o 1 r e n Y e s t f 8 i b r o o 1 c t N l t e f i s I i s d o o s o a t s r n D r , f s d i o E s e c e g n h a s ) S d ? t , o a 2 a U ( ? r c s E l I C i g S e e G l , l d o d s , T 3 e a r I a r G r 1 S a g l g w , , I b u b e u G u v U s n s i a , s G r e g e e s W p h h t e S t h o u s , c o s r s e W e n r g o a o o o f G D c ( D n o 0 N 1 1 1 N
N l a ? c " o s l t e y k n c a o e p r t e s h a t l l e a r b A " 5
c c A B b b b 2 A B C a a a A B C
t c c C e p X s ? 5 e r d c h e t B n i i b X a N w C X t 3 n y i t i l i a c A b m X a b b ) t 2 A B X s ( a a a 2 A B C g t s n i a r l l e t l a i f b e e x h Y 5 t t h s t o I
y t i c i t s , a l M p T m , L ? u i T s d l e , i o M s m r U , d o L e w d U o , a l f T r g o S l l s , e l i U w o s S , e v T i e h G s t , e e U h r o A G c 5 N 1
c B b X C X
c A X b b A B X a a a 2 A B C
C X d e X n 4 n e a l c c h A B t p f n N b b X B C X o o i a 2 t e C a g l l a a X n b i t s X A a n r 1 a a i d A B s t i ? n r m e o r i e c t i f ) 2 f c ( t r u C X o s e h d s X e a 4 r e r e g h c h t b t B u n X b s I s i C X 3 8 Y Y c 1 A b b X A B X 2
t x e ) n S t h x t S i ) w e P l y l n ( u t h r k a s t c h e i e i v u r t w a a q e l d l t d v o d l e e e e l t l l k l l a x n l a e l a t a t s l t n n s b n r s i n i o i a e f r e t e b i e b b l d a t h t t w s l u l e s o t u u h h u o a s u a m w h h d n m r S r S n e S n e S e o d S a i v v c S e P ( s P o P o i e c n e s 1 2 3 D i
N o t . c ? c d a e n v r o e i r s e b t i r o c e t d s n o r a r f e g h a s t a s I C B 7
h t i w y t i t s l i a l b l a a t s b e g h ? n t i d r o e e t n t l i t i f c t a e e n i h p t s a e s I r m
U t r e n t e i a c e i f f r g e ) o c 2 ( y e t i d a m r r o g f i b n u u s ? 3 e e h t n t h a s f h I o t
f o l i o s y t i c ? i t ) s y a a l l p c ( h g A i T h a p t i u o s r I g 6 1
4 c c A B b b b A B C 2 a a a A B C
y t i c i t s a l p ? h ) g i 4 h e e g v a a h p , s 6 l i 9 o 1 s 8 e 1 h t N I o D D ( 8
d c c e B C n b n C 4 a a l p Y c C A e n b b h o i t t 2 A B f l a a a o l A B a e t g s a n i n i e a r h t d s ? t i n m e r r i o e c ) t i f 2 f ( t r u o s e h c d e C r a s 4 e r e g h h t b t s u n N c c I s i
d e r i u q e r t o n S S P
t k n e c a r m t n e g i h l t t a ? s i t 5 s d n r n o a n a n o h c l w c e o g N e v h n d e i l s d ? a ) ? r s r e k g s 6 t Y b r l o N r r l 9 e ) o e u c i 1 u 1 e a r w o w s ( W f o k l s 8 l e 1 a e d c r o v d t a i a u r t s n r t y g 2 r a e a t a n b h u 4 s o e o s u c 5 h 0 e s g t e 1 c h n n i s e t y N e o r n n I Y f r o f D e o a D o ( b p c t o n i t A l e l e 7 i N h h w W t
d e r i u q e r y l l a m r o n t o n S S P
A B b b b A B C 2 a a a A B C
A b b X e A B X h a a a 2 t A B C f n o o i ? t e a m g l l a a r n t e i s t a n r r i t d o s h t i n r s e o e i c ) h i f f 2 ( t u n s e i c d d e C a e r r X e g n X h t b n 4 a l u s s I p c c A B b X 7 N b B C X 1 a 2 C b A a a A B
y t i c a p a c g n i ? r t a s e a l l b a e b t a e u h t q e h t d a a e e r n e r e h t d s n I u 9 1
e c a r e f t h u N X X o t 3 n f s e s o h i e t e h e m e t s g d n f d r n o o n a i a t e e i r r s t s n g r - e e a g - s e b h r a t h e b p u f m u s o t s p x r , n i " e e m m n p t m r r e s u e n b u t e a p u t e ) n e m e e s a r h e e l h h t e t d r t c u " P e t i G , , d t t t r d a t r r o a x s c e " g r x u r e t e h o g t t t m b e r n h n s w b o s u u o t b u c e n s c n n s a b u a s i l y s i s i e i r p a m h d h c h w t e r t t s d l e h r i e s f e E r t G o I n u ( n d " a I ) ) 1 2
Appendix C - Example of rehabilitation of track beds SBB/CFF C.1 - Typical track bed construction C3 C2
Fig. 31 - Schematic cross-section
Table 2 : Terms and examples
The basic data are intended for the geotechnical expert and for the project planner. They must be collected as comprehensive as possible in planning stage 1 and incorporated into the geotechnical remit.
Check list for basic data collection: -
yes no The track belongs to group 1 yes no Check the economic implications of reinstatement/additional maintenance Additional maintenance is justified economically no
the the mea measur sures es requi required red for for the the infra infrast struc ructur ture, e,
deter determin minati ation on of the type type of of super superstr struct uctur ure. e. Sandy gravel blanket layer
exist xistin ingg cond condititio ions ns ar are uncl unclea earr,
infr infras astr truc uctture ure pr prob oble lems ms ari arise se,,
difficu difficulti lties es are are likely likely to to be encounte encountered, red, when when tr track ack loadi loading ng is increase increased. d.
the the tra track ck does does not not run run on an emba embank nkme ment nt,,
the the soil soil is sens sensititiv ivee to to rain rain wate water, r,
tren trench ches es or cune cunett ttes es are are inef ineffe fect ctiv ive. e.
Generally, infrastructure drainage should be constructed at the time when the superstructure is renewed. The presence of water in the infrastructure causes the loss of bearing capacity of the individual layers and under dynamic traffic loading, the layer boundaries can be disturbed. distu rbed. This leads to the inter-mixing of the infrastructure materials and even to mud rising into the ballast. ball ast. The penetration of water into the infrastructure, therefore, must be prevented. For dimensioning drainage systems, systems , a run-off coefficient of 0,8 is assumed for the superstructure. The minimum diameter of drain pipes is 0,20 m. When using pipes of synthetic materials, products made of polyethylene should generally be preferred (avoid PVC). So as to prevent inter-mixing of the layer arrangement of the infrastructure under dynamic traffic loading, the dynamic filtering criteria at the interfaces must be observed. This generally requires the installation of a filter layer. In many cases, a geotextile is sufficient to separate the adjacent layers.
Appendices C.4 C.4 - Rep Repair met metho hods ds for for found foundat atio ion n layer layerss C.4.1 -
prot protec ectition on laye layerr of grav gravel el (CFF (CFF), ),
prot protect ection ion laye layerr of grave gravell (CFF (CFF)) and and non-w non-wove ovenn geotex geotextil tile, e,
drain drainage age layer layer of of perm permeab eable le gra gravel vel and and geote geotexti xtile, le,
drai draina nage ge lay layer er wit withh imper imperme meab able le mem membr bran ane, e,
ligh lightt mate materi rial al with with grav gravel el..
C.4. C.4.22 -
SubSu b-ba ball llas astt laye layerr of grav gravel el (CFF (CFF))
incr increa ease se the the bea beari ring ng capa capaci city ty,,
ensur nsuree filt filter erin ingg stab stabililitity, y,
keep permea meabil bility ity low, ow,
reduce frfrost ef effects.
The thicker the layer is, the better it can fulfil fulfi l these functions. Generally, Generall y, a depth of 0,30 m is sufficient. However, when the bearing capacity of the ground is too low (CBR < 4 %), a depth of 0,30 m is inadequate and it should be increased to 60 - [40 • log CBR] (depth in cm, CBR in %) when settlement under dynamic loading is acceptable. When this is not the case (settlement under dynamic loading is too high), the method described in point C.4. C.4.66 - page 81 81 should should be used. A layer depth of 0,30 m requires about 0,7 t of material per m2. This method can be used when the soil on the site contains up to 85 % fines (screen gauge < 0,06 mm). If the percentage percentage of fines is greater, greater, the filter filter stability stability and protection protection against fines is no longer ensured.
Appendices C.4. C.4.33 -
Sub-b Su b-bal alla last st lay layer er of of grav gravel el (CF (CFF) F) and and non non-w -wov oven en tex textil tilee
This method is used when the content of fines in the soil in situ exceeds 85 % (screen gauge < 0,06 mm). It requires requires the installation installation of a non-woven non-woven geotextile under under the sub-ballast sub-ballast layer (for protection) as an additional filtering layer. As a protection against sharp edges and to improve the filtering process, a sand layer of at least 0,05 m thickness is installed underneath the geotextile. This method is recommended, for example, if the subgrade consists of marl or its degeneration products.
C.4. C.4.44 -
Drai Draina nage ge laye layerr of of perm permea eabl blee gra grave vell and and geot geotex extil tilee
When the ground water table is high and, exceptionally, the water can seep from the bottom into the foundation layers, the use of CFF gravel as a sub-ballast layer (for protection) is not permitted. Since CFF gravel is relatively impermeable, pore water pressure can build bui ld up which, under dynamic loading, can result in break-up of the foundation layer and local rising of fine particles. In this case, the foundation layer must consist consis t of permeable gravel, permitting the pore water to run into the side drains without pressure. The coefficient of permeability must not be lower than 10-5 m/s. Generally, this requirement is fulfilled by gravel 1 (Standard SN 670 120). In order to ensure the filtering action, a non-woven or finely woven geotextile is installed underneath the foundation layer. A sand layer at least 0,05 m thick should be provided under the geotextile. The surface of the drainage layer is protected by a "sub-ballast" blocking layer so that the surface water cannot infiltrate, but runs away from the railway subgrade.
C.4. C.4.55 -
Drai Draina nage ge laye layerr with with an imper imperme meab able le memb membra rane ne
Installation of an impermeable membrane prevents water from penetrating into the infrastructure. This method is only suitable for track with light traffic and on embankments. The bearing capacity of the existing infrastructure must be adequate. The thickness of the synthetic geomembrane must not be less than 1,5 mm. When laying the membrane, the ends must be welded together in accordance with the manufacturer's instructions. A drainage layer of permeable material (e.g. (e.g. clean sand) with a permeability coefficient of not less than -5 10 m/s and with a thickness of 0,10 mm must be installed under the geomembrane. In this layer, the water must drain away laterally, otherwise a damp path could form under the geomembrane, which would soften the ground and reduce the bearing capacity at this point so that the ballast and geomembrane "float" on the natural subgrade. A layer of sand, or possibly po ssibly gravel 0,05-0,10 m deep must be installed in stalled on the geomembrane geo membrane in order to protect it against the ballast so that it will not be pierced by the ballast particles.
Measurement of surface movements
• Plots showing cumulative displacements of several lengths of rail. • Measurement survey reference points (vertical and horizontal). • Measurement of surface rotations. -
Measurement of sub-surface movements
• Inclinometer surveys. • Establishment of position of slip planes with alkathene tubes. • Measurement of settlements. -
Piezometric surveys
• Level of water table. • Pore water pressure. -
NB : some of these systems may include equipment which can trigger a suitable warning system if the movements become critical. Drainage -
Drainage of embankments and slopes1
• Ditches for collecting surface water, for example toe drains or crest drains; it should be noted that these ditches may be the cause of instability and, if necessary, should therefore be sited some distance away (several metres or more according to the nature of the soil and the height of the slope) and should have impermeable linings. • Deep drains to dewater a slope as well as collect surface water (Fig. 33 - page 83). Construction of deep drains in unstable ground is very specialised and must be undertaken in the most favourable hydrological period and be monitored by a system of piezometers. • Interceptor drains, used on natural slopes and cutting and embankment slopes (Fig. 34 page 83) where seepage occurs in wet weather. 1.
5 6 1 Deep drain
5 Piezometric level after installation
3 Perforated pipe
6 Drainage ditch
2 1 Direction of steepest slope
2 Drainage ditch
Fig. 34 - Example of interceptor drains
Comments on figures 33 and 34 The trenches of both deep and surface drains can be infilled with free draining aggregate or pebbles. If pebbles are used, the trenches must be lined with a filtering, anti-contamination geotextile. -
to lead water, which ponds in an embankment, towards the side slopes or to stop longitudinal flow under the track at the cutting/embankment transition point. This is only minor work but it may have a considerable effect on track geometry while it is being carried out. -
Counterfort drains in embankment or cutting slopes (Fig. 35 - page 84 )
The base of the drain must be located well below the slip surface so that as well as having a hydraulic function it also also acts as a buttress. Temporary support should be given to the track when work is in progress on embankment slopes.
3 ~1,5 m
4 Slip surface
5 Topsoil
3 Drain Fig. 35 - Example of a counterfort drain
Sub-horizontal drains
Set into cutting or embankment slopes to drain deep water bearing layers (perforated plastic pipes possibly surrounded with a geotextile, and other arrangements). -
Electrochemical stabilisation of soil consists of improving the cohesive soil in situ by injection of calcium chloride with the application of 60V direct current over a prolonged period of time. The advantage of this method is that the cohesive soil need not be replaced. Electrochemical stabilisation results in an improvement of the rheological and mechanical properties of unstable cohesive soil, improving its bearing capacity, consistency and resistance to water and frost. Preliminary field and laboratory tests must be carried in order to determine whether this method is suitable for the particular case.
~ h2 --
3 Topsoil removed
4 Permeable layer Fig. 36 - Example of a berm
This method is not recommended when the slip circle is too high on the slope or when the embankment is set on an inclined terrain. (The dimensions of the berm, h/2 x h/2, are only applicable where the slip circle ends close to the base of the slope).
Mechanical action, by retaining the base of a slope This method is used when the available ground space is insufficient for construction of a berm. Most of the methods described below also have the effect of loading the toe of the slope.
2 Fig. 37 - Example of a piled concrete beam
Retaining wall , cast in situ deep foundation, if necessary, or a simple reinforced concrete beam
set on a group of piles (Fig. 37) or anchored in the underlying strata (Fig. 38).
Fig. 38 - Example of an anchored beam
Traditional piles (Fig. 39) : rows of staggered piles placed in the lower part of the slope (wooden,
steel or reinforced concrete piles, prefabricated or otherwise). Sometimes it may be advisable to bore holes beforehand to reduce vibration effects due to ramming. The piles must penetrate beyond the surface of the slip.
Fig. 39 - Example of stabilisation of the base of slope using conventional piles
NB : when the soil under the embankment is very prone to settlement, the reinforcements can be made more effective by inclining the piles as required (Fig.43 - page 90). -
Micropiles: staggered over the whole surface of the unstable part of the slope. Each micropile
(several centimetres in diameter) is reinforced with a steel tube and/or one or more round steel bars and injected with a cement grout (possibly containing an additive). If appropriate, the treatment may be limited to discrete short sections of the slope in the form of injected counterforts. While injection work is taking place, any movements must be carefully monitored. When elements of reduced inertia are used (micropiles, old rails, low diameter piles, etc) for stabilizing earth masses, their axial resistence (nailing effect) rather than their shear resistence should be used. In case of using micropiles, a "wall effect" may be introduced, in order to give inertial resistence to each set of micropiles installed in a cross section of the mass to be stabilized. This can be achieved by grouting, not only the roots of the micropiles within the firm ground, but also the upper part, keeping a distance between micropiles adequate for the grounting of the different units to overlap.
Injection of the body of the earthwork (Fig. 41 - page 89): treatment of earthworks formed from
cohesive soils. An aerated, highly viscous form of cement-sand grout should be used (for example, 3 parts (weight) sand for 1 part cement and a foaming additive) to form a grout plane in the slip surface (or surfaces if there are multiple slips). A series of grouting tubes are installed in staggered rows in the bank, and the grout is injected below the slip surface. Injection should start with the lower rows. 87
Fig. 40 - Improvement technique of transition zones without disturbance to traffic by means of hydraulic fracture grouting (CEDEX Spain)
Injection may be used in ballastless track to control the settlements. -
Injection of ballast pockets
• substitution of material which has slipped by a non-cohesive material, • surface treatment: this can help to avoid erosion of the surface. -
Planting vegetation: favours transpiration and strengthens the earthwork. However, it must be cut
back as required. -
Protective cover of non-cohesive soil (Fig. 42).
This process, which is very common in Northern Europe and North America, performs three tasks: drains water from the ground, protects the bank from water erosion, avoids failures occurring during thaws in harsh climates (liquefaction and erosion of the surface soil).
1 Granular soil 2 Cohesive soil 3 Longitudinal drainage
Fig. 42 - Example of a protective granular layer
NB : if the foundation soil is of very poor quality for a considerable depth or if the slip surfaces are deep seated, especially when existing subgrades are being widened or deepened, the problems may be so difficult to resolve that special designs need to be produced by a geotechnical expert.
Fig. 43 - Examples of stabilisation measures for embankments on soils of low bearing capacity
The following figure shows an example of the use of a mounting sleeve in the installation of a embankment plate (VR, Finland)
b: Plate mounting plan Fig. 44 - Example of the use of a mounting sleeve
in the installation of a embankment plate (VR, Finland)
Appendices D.2 - Rock slopes (natural or excavated) Detection and monitoring methods The aims of these methods are to monitor movements in rock slopes before, during and after repair work is undertaken. Electric trigger wires which activate a special signal. Surface measurements of movement
Measurement of deep-seated movements (in boreholes or wells)
Measurement of load (e.g. in rock anchors). Other measurements (eg. endoscopic examination of bore holes, geophysical measurement on the
surface or in bore holes, passive microseismic measurements).
Methods of rockfall protection Track side barriers
This solution is frequently adopted for a number of reasons (the problem may originate in an area that is inaccessible or too extensive; the land may not belong to the Railway; barriers are easy to erect from within the railway boundary; they are easy to maintain and inspect, etc.). For a barrier to be effective, it must be high enough to intercept any falling boulders and strong enough to resist the impact. From this point of view, a flexible barrier (which can absorb kinetic energy by plastic displacement or bending) is preferable to a rigid one.
Appendices "Rail-sleeper" barriers (or similar) (Fig. 45), which are quite effective in the case of rock falls of limited
1 End stays
10 Direction of slope
11 Lower post stay
3 ≥ 3 m
1 Earth bund 2 Steepest slope possible with available materials 3 Debris catchment area accessible to earthmoving machine Fig. 47 - Example of an earth bund with debris catchment area Gabions barriers (Fig. 48).
Appendices Barriers placed on the slopes (using the same techniques as above).
It is important that the barriers are placed where the falling rocks are likely to have the lowest kinetic energy (Fig. 49).
3 Track to be protected
Fig. 49 - Example of barrier placed on a slope Extra wide cess at the base of a rock cutting (stone traps).
This technique of allowing extra width is used for rocky cutting slopes both on new lines (see point 2.3.2.2 - page 24) and when slope stabilisation is undertaken. RITCHIE1 has made design recommendations, which are reproduced in Fig. 50; they must of course be adapted for each case (presence of other berms on the slope, nature and weathering of the ground, etc.).
Fig. 50 - Recommendations for the dimensioning of extra width at the bottom of slopes for protection against rock fall (according to RITCHIE)
Table 4 : Protection against rock fall
Incline of bank
Height of bank h (metres) 5 - 10 10 - 20 > 20
Width of trap l (metres) 3 5 6,5
Depth d (metres) 1 1,5 1,5
(degrees) 80 to 90
Control of direction of fall
Appendices Manual removal
This is used for smaller rocks. It is a day-to-day maintenance operation, but care should be taken to ensure that removal of one rock does not cause instability of a larger mass.
NB : the use of explosive for these operations is a very difficult operation, which requires detailed preparation, many precautions and specialised operators. Protective gallery (Fig. 51) This very expensive solution is used, when rock falls cover a wide area or in the case of a very steep bank, when no cheaper solution is practicable.
Fig. 51 - Example of a protective gallery
Stabilisation of rock slopes Surface treatment
Appendices to a minimum thickness of about 0,05 m on the most prominent areas of the rock face. Water should be directed away from behind the face to avoid the danger of further frost action.
NB : sometimes, it is sufficient to treat only the offending parts with unreinforced sprayed concrete.
3 Weep holes
4 Sub-horizontal drainage
Fig. 52 - Example of protection with sprayed concrete Support buttresses
This procedure is used for rock overhands with a clearly subscribed unstable part (Fig. 53).
Appendices Rock anchors
3 5 1 Grouted anchor
5 Stable rock
3 Protective facing Fig. 54 - Example of prestressed anchors
1 Un-prestressed anchor 2 Slip surface 3 Stable rock Fig. 55 - Example of a non-prestressed anchor
Appendices D.3 - Voids and subsidence beneath the track The method of treating voids and subsidence varies according to the nature (cause and subsequent development) of the problem. A distinction is made between:
Problems with natural causes Such problems occur where soluble layers in the ground are dissolved by running water, e.g. gypsum, rock salt, limestone and chalk). The ground overlying the resulting void collapses and this may ultimately progress upwards to the ground surface (subsidence and swallow holes). Dissolution may be accelerated as a result of industrialisation and urbanisation (e.g. industrial pumping). Even if the areas of soluble soils are known, the voids themselves are very difficult to detect. When a sensitive area is identified (e.g. when subsidence occurs), it is necessary to define the potential problem areas: -
The most common method of treatment is grouting. This may be carried out through the small boreholes referred to above. The quantities injected at each point must be carefully monitored as the injection tube is raised. The voids are filled by gravity with a material not liable to settlement; care should be taken to avoid using materials which are too permeable, thereby forming a vertical drain which may generate further problems. The upper part must be filled in with materials that are resistant to rainwater (concrete, sand/cement grout or similar mixture), which is sometimes aided by vibration. At the same time, the drainage system should be checked to ensure that it is watertight with respect to the subgrade. In very difficult cases, the track layout may have to be modified or load-distributing slabs laid under the track.
Man-made problems These include disused quarries, mines or war trenches. Where they are known to exist and can be inspected, they must be: -
Mud flows (erosion of both fine and coarse material) Attempts may be made to prevent the formation of mud flows by drainage, planting shrubs and trees or building dykes.
Avalanches in mountainous regions Appropriate solutions include planting of forests on the slopes, protection works in areas where avalanches form and works to protect the track.
Snow-drifts To protect exposed sections of the track from drifting snow, hedges should be planted or barriers or fences erected at an appropriate distance from the track. These will stop the snow before it reaches the track. In extreme situations, it may be necessary to build protective galleries.
Flooding and erosion near water courses and lakes The railway subgrade can be protected against flooding and erosion by structures such as: -
Appendix E - Example of methodology for bed layers design in existing lines (ADIF, Spain) E.1 - Basis of design The methodology used for establishing the thicknesses of the bed layers (ballast + subballast) is based upon the concept of settlement-conservation coefficient and upon Dormon's law (Question ORE D 117, Rep. 28) which have been used to define the thicknesses given in point2.4.2 - page 36.
E.2 - Evolution of the levelling operations with traffic A reference traffic To of 45 Mt is considered. Let T [Mt] be a fictitious traffic, corresponding to a real traffic which has circulated on the track since the last rail renovation (or traffic opening), obtained according to the formulation and coefficients given in UIC Leaflet 714, paragraph 1. The relative traffic τ is defined as τ = T/To. Given a relative traffic τ, which has been made necessary a number Z of levelly operations Z = k Z1, where Z1 = 0,45 (0,8 τ + 20,2 τ - 1), and k is the settlement-conservation coefficient. It is experimentally verified that the variation of k with τ is small. When Z is not known, in order to obtain the k value for a given line, time intervals of at least 5 years must be considered, and if τ is the total relative traffic when a levelling operation is carried out, and τ + Δτ the total relative traffic when the next levelling operation is necessary, then k can be established with a sufficient degree of accuracy by means of the formula: K = 1/ (0,36 + 0,06.2 0,2 τ + 0,1
) Δτ
When more than 2 successive levelling operations are considered, several values of k may be obtained through the procedure described. Then, a representative value of k is taken as the arithmetical mean of those values.
E.4 - Application of Dormon’s law Dormon's law relates k to the maximum stress transmitted to the platform. This law indicates that if an axle transmits a stress σ1 to the platform of a track having a k1 coefficient, this track will behave as having a k2 coefficient for a transmitted stress σ2 verifying: σ2 / σ1 = (K 2 /K 1) 0,2
NB : In case more precise data are not available, the following reference values for ballast and subballast may be considered: Table 5 : Reference values for ballast and subballast
c: Cohesion ϕ:
E.8 - Modification of a track K coefficient If the l coefficient of a track has to be modified, the following procedure may be followed. The present value k1 of the coefficient is determined and, preferably by elasto-plastic analysis, using the laws and methods of the continuum mechanics (or experimentally) the stress, transmitted to the platform, under a rail, by the dynamic loads acting on the track, is obtained. The object is to change the value k, to a new value k2. By applying Dormon's law, the new stress σ2 to be transmitted to the platform will be σ2 / σ1 = (K 2 /K 1)0,2. Because of the modification to be introduced in the superstructure (track and ballast). σ2 will depend upon the thickness, esb, of the subballast layer (in general, σ diminishes as esb increases). An easy approach to obtain esb will consist upon considering 4 different thicknesses of subballast (for instance 0 m, 0,2 m, 0,3 m and 0,4 m) and adjusting a function σ = σ (esb), from which esb would be obtained for a σ2 value of the stress transmitted to the platform. The values obtained for esb may be rounded off to multiples of 5 cm. The value obtained for esb may be different to the value finally adopted for other reasons (for example, for homogeneity of adjacent sections).
Bibliography 1. UIC leaflets International Union of Railways (UIC) UIC Leaflet 700: Classification of lines - Resulting load limits for wagons, 10th edition, November 2004 UIC Leaflet 714: Classification of lines for the purpose of track maintenance, 3rd edition of 1.1.89 UIC Leaflet 722: Methods of improving the track formation of existing lines, 1st edition of 1.1.90 UIC Leaflet 724: Track equipment for 25 tons (250 kN) axle loads on ballasted track, 1st edition, May
2. Minutes of meetings International Union of Railways (UIC) Way and Works Committee (Item 9.1.5 - Earthworks and track bed construction for rail way lines - New edition of Leaflet 719), June 1993
3. ERRI reports European Rail Research Institute (ERRI) - International Union of Railways (UIC) ERRI D 117/RP 13: Optimum Adaptation of the Conventional Track to Future Traffic - Hydraulic performance of track bed structures and soil u nder the influence of rainfall, 1.10.1979 ERRI D 117/RP 15: Optimum Adaptation of the Conventional Track to Future Traffic - The influence of frost on the foundation of railways: Design of protective measures, 1.9.1980 ERRI D 117/RP 16: Optimum Adaptation of the Conventional Track to Future Traffic - Filtration and drainage. Part 1: General filtration rules suitable for drainage systems, 1.4.1981 ERRI D 117/RP 21: Optimum Adaptation of the Conventional Track to Future Traffic - Filtration and drainage. Part 2: Filtration rules suitable for materials of track bed structures, 1.9.1981 ERRI D 117/RP 24: Optimum Adaptation of the Conventional Track to Future Traffic - Filtration and drainage. Part 3: Use of geotextiles, 1.4.1983 ERRI D 117/RP 28: Optimum Adaptation of the Conventional Track to Future Traffic - Design charts for the track/foundation system, 1.9.1983 ERRI D 230.1/RP 3: Bridge Ends - State of the Art Report (Report only available in English), 1.11.1999
5. International standards International Organization for Standardization (ISO) CEN ISO/TS 17892-2:2004 Geotechnical investigation and testing - Laboratory testing of soil - Part 2: Determination of density of fine grained soil, 2004 CEN ISO/TS 17892-5:2004 Geotechnical investigation and testing - Laboratory testing of soil - Part 5: Incremental loading oedometer test, 2004 CEN ISO/TS 17892-7:2004 Geotechnical investigation and testing - Laboratory testing of soil - Part 7: Unconfined compression test on fine-grained soil, 2004 CEN ISO/TS 17892-10:2004 Geotechnical investigation and testing - Laboratory testing of soil - Part 10: Direct shear tests, 2004 CEN ISO/TS 17892-12:2004 Geotechnical investigation and testing - Laboratory testing of soil - Part 12: Determination of Atterberg limits, 2004 EN ISO 14688-1:2002 Geotechnical investigation and testing - Identification and classification of soil - Part 1: Identification and description, 2002 EN ISO 14688-2:2004 Geotechnical investigation and testing - Identification and classification of soil - Part 2: Principles for a classification, 2004 EN ISO 22476-1:2005 Geotechnical investigation and testing - Field testing - Part 1: Electrical cone and piezocone penetration tests, 2005 EN ISO 22476-2:2005 Geotechnical investigation an d testing - Field testing - Part 2: Dynamic probing,
2005 EN ISO 22476-3:2005 Geotechnical investigation and testing - Field testing - Part 3: Standard penetration test, 2005 EN ISO 22476-4:2005 Geotechnical investigation and testing - Field testing - Part 4: Menard pressuremeter test, 2005 EN ISO 22476-5:2005 Geotechnical investigation and testing - Field testing - Part 5: Flexible dilatometer test, 2005
EN ISO 22476-6:2005 Geotechnical investigation and testing- Field testing - Part 6: Self-boring pressuremeter test, 2005 EN ISO 22476-8:2005 Geotechnical investigation and testing- Field testing - Part 8: Full displacement pressuremeter test, 2005 EN ISO 22476-9:2005 Geotechnical investigation and testing- Field testing - Part 9: Field vane test,
2005 EN ISO 22476-12:2006 Geotechnical investigation and testing - Field testing - Part 12: Mechanical cone penetration test, 2006 EN ISO 22476-13:2006 Geotechnical Geotechni cal investigation and testing - Field Fie ld testing - Part 13: Waterpressure test in rock, 2006
6. Miscellaneous Design and construction of earthworks ADIF Pliego de prescripciones técnicas tipo para los proyectos de plataforma, 2006
BR - Specifications for Roads and Bridges. Department of the Environment. HMSO - The moisture condition test and its potential applications in earthworks. Transport and Road Research Laboratory - Supplementary Report 522, 1979
DB - DIN 18127 Proctorversuch - DIN 4084 Gelände - und Böschungsbruchberechnungen - DS 836: Vorschrift für Erdbauwerke - ZTVE-StB 76/78: Zusätzliche Technische Vorschriften für Erdarbeiten im Strassenbau (Additional technical contractual conditions and guidelines for earth work in road construction. Part 14.1: Testing methods for soil compaction), 94/97
RFI Tecnica di impiego delle terre. CNR-UNI 10006, 1963
SBB/CFF R 211-1:Infrastructure 211-1:Infrastructure et ballast. Prescriptions pour lignes lign es nouvelles et réfection des lignes lig nes anciennes,
Schaible L. Frost und Tauschäden an Verkehrswegen, W. Ernst und Sohn, Berlin, 1957
SETRA-LCPC - Guide technique : réalisation des remblais et des couches de forme,
SNCF - Cahier des Prescriptions Communes : Book 5-12, 5-1 2, Volume II, Grands Terrassements - Notice technique relative aux ouvrages en terre d'une ligne nouvelle à très grande vitesse systems,
Others Beskow G. Soil Freezing and Frost Heaving, Statens Väginstitut, Stockholm, 1935
Ril 836 Erdbauwerke planen, bauen und instand halten, 1999
TP BF-StB part E - Technical testing instructions for soil and rock in road construction. Surface covering dynamic compaction control methods, 2nd edition 1994
Report "UIC 719 r.pdf"
Share & Embed "UIC 719 r.pdf"