what is formation? formation is a prepared flat surface, which is ready to receive ballast of the...
TRANSCRIPT
![Page 1: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/1.jpg)
![Page 2: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/2.jpg)
What is formation?What is formation?
Formation is a prepared Formation is a prepared flat surface , which is flat surface , which is ready to receive ballast of ready to receive ballast of the track.the track.
It is important constituent It is important constituent of the track as it supports of the track as it supports the entire track structure.the entire track structure.
![Page 3: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/3.jpg)
Function of formation
i. To provide a smooth and uniform bed on which the track can be laid.
ii. To bear the load transmitted to it from the moving loads through the section of ballast.
iii.To facilitate drainage.iv.To provide stability to track.
![Page 4: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/4.jpg)
General Description• Prepared either by doing additional earth
work over the existing ground or by excavating existing surface and making cutting.
• Can be either in the shape of embankment or a cutting.
• Height of formation depends upon the ground contours and the gradient adopted.
• The side slopes depends upon the shearing strength of soil.
• The width of the formation depends upon the number of tracks to be laid & gauge of track.
![Page 5: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/5.jpg)
DEFINITIONS
BLANKET
SUB - GRADE
TRACK- FOUNDATION
TRACK STR.
FORMATION
B A L L A S T
CESS
SUB - SOIL
![Page 6: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/6.jpg)
Classification of soil
Good soils Coarse grained soil
Other than Good soils
Fine grained soils such as silts sandy and silty clays
![Page 7: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/7.jpg)
Grain size classificationGravel Coarser than 2.00 mm
Coarse sand 0.6 mm to 2.00 mm
Medium sand 0.2 mm to 0.6 mm
Fine sand 0.06 mm to 0.2 mm
Silt 0.002 to 0.06 mm
Clay finer than 0.002 mm
![Page 8: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/8.jpg)
SOIL – THE SUPPORT SYSTEM
• Mother Earth.
• Has it unlimited Capacity?
• Appears simple but least understood.
• Mostly taken for granted.
![Page 9: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/9.jpg)
SOIL?????
• What is Soil?– Residual– Transported
• Soil Mechanics
• Geotechnical Engineering
![Page 10: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/10.jpg)
HOW SHALL WE PROCEED
• Knowledge of Soil Mechanics– Soil Elements– Common Tests on Soil– Soil Classification– Soil Surveys
• Earthwork in Railway Projects– Definitions– Execution of Earthwork– Blanket
![Page 11: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/11.jpg)
INDEX PROPERTIES• Mechanical (Sieve) Analysis
– Coarse grained soil
• Hydrometer analysis– Fine grained Soil
• Consistency Limits– Liquid Limit LL - WL
– Plastic Limit PL – WP
– Shrinkage Limit
– Plasticity Index PI - IP
![Page 12: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/12.jpg)
SOIL ELEMENTS
Bulk density gm/cc
γ=W/Vt
Dry density gm/cc
γd=Ws/Vt
Voids Ratio e=Vv/Vs
Porosity in %
n=Vv/Vt
Water Content in %w=Ww/Ws
Degree of Saturation in % S=Vw/Vv
![Page 13: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/13.jpg)
PARTICLE SIZE DISTRIBUTION
D10 – Effective size
Coefficient of uniformity - Cu
Cu=D60/D10
Coefficient of Curvature Cc
Cc=(D30)2/D60XD10
D60D30D10
![Page 14: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/14.jpg)
PARTICLE SIZE CURVE
Curve No.1 Cu = 10 Cc = 2.5
Curve No.2 Cu = 1.4 Cc = 1.2
Curve No.3 Cu = 4.0 Cc = 1.6
Curve No.4 Cu = 7.6 Cc = 1.0
![Page 15: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/15.jpg)
LIQUID LIMIT - ATTERBERG’S LIMITS
Liquid Limit is the water content at which 25 blows cause the groove to close.
![Page 16: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/16.jpg)
PLASTIC & SHRINKAGE LIMIT
Plasticity Index PI or IP = Liquid Limit (LL or WL)
– Plastic Limit (PL or WP)
Plastic Limit is water content at which 3 mm diameter roller of soil starts crumbling
Shrinkage Limit is water content beyond reduction which does not cause volume decrease
![Page 17: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/17.jpg)
CLASSIFICATION IS:1498 - 1970
GRAVEL SAND
COARSEBOULDERS
GW GP GM GC SW SP SM SC
SILT & CLAY
GW-GM
GP-GM
GW-GC
GP-GC
GW-GP
SW-SM
SP-SM
SW-SC
SP-SC
SW-SP
Fines<5% Fines>12% Fines<5% Fines>12%
Fines between 5% to 12% Fines between 5% to 12%
75>PS>4.75mm 4.75>PS>75μ
GM-GC
SM-SC
![Page 18: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/18.jpg)
COMPACTION – Primarily Expulsion of Air
![Page 19: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/19.jpg)
COMPATION OF SOILS
18”4.54 Kg
γd = γ/(1+w/100)ID = {(emax-e)/(emax-emin)}x100
ID - Relative density – cohesion less soils
![Page 20: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/20.jpg)
PERMEABILITY OF SOIL
• V = ki– V – Velocity of flow
cm/sec– k – coefficient of
permeability• Porosity of soil• Shape and size of voids
– i - Hydraulic gradient
Type of Soil
K in cm/sec
GRAVEL 102 to 1
SAND 1 to 10-3
SILT 10-3 to 10-6
CLAY Less than 10-6
![Page 21: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/21.jpg)
SOIL SURVEYS
• RECONNAISSANCE SURVEY
• PRELIMINARY SURVEY
• FINAL LOCATION SURVEY
![Page 22: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/22.jpg)
RECONNAISSANCE SURVEY
• General Idea
• No laboratory tests
• Other Surveys, topological maps, geological
• Visual Inspection
• Behaviour of existing structures
• Prospective Borrow Area - Soil & Blanket
![Page 23: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/23.jpg)
PRELIMINARY SURVEY
• Sampling at about 500 m interval• May be for alternative alignments too• Sub-surface soundings• Auger Sampling normally, SPT may be done.• Normally no undisturbed samples• Bore log from disturbed samples • Split spoon sampler• Mechanical Analysis & Index Properties
![Page 24: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/24.jpg)
FINAL LOCATION SURVEY• Sampling at about 200 - 300 m interval• Detailed Investigations – May be at very close
intervals particularly at– Bad Soil Locations– Location of Important Structures
• Major Bridges• High Banks• Deep Cuttings
• Undisturbed Soil Samples• Engineering Geologist• Water table Data and seasonal variations• Additional tests like shear strengths, consolidation,
vane shear, free swell etc.• Sources of Soil and Blanket Material
![Page 25: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/25.jpg)
• Cohesive subgrade – Subgrade constructed with soil having cohesive behaviour i.e. shear strength is predominantly derived from cohesion of the soil. Normally soil having fines (< 75micron) exceeding 12% (As per IS Classification all fine grain soils, GM, GM-GC, GC, SM, SM-SC& SC )
• Cohesionless subgrade – subgrade constructed with cohesionless, coarse-grain soil i.e. shear strength is predominantly derived from internal friction of the soil. Normally soils having fines less than 5% (As per IS Classification GW, GP, SW & SP types of soils)– Other type of soils having fines between 5 to
12% needs detailed study.
![Page 26: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/26.jpg)
• Dispersive Soil – are those, which normally deflocculate when exposed to water of low salt content. Generally, dispersive soils are highly erosive & have high shrink & swell potential.
• Unstable Formation – Yielding formation with non terminating settlements including slope failure, which require excessive maintenance efforts.
![Page 27: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/27.jpg)
FORMATION IN BANK
![Page 28: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/28.jpg)
DESIGN OF RAILWAY FORMATION
• A stable formation should be able to sustain the track geometry under anticipated traffic densities and axle loads during service under most adverse conditions of weather & maintenance of track structure, which are likely to be encountered.
• The formation should be structurally sound – not to fail in shear strength –dead and live loads
• and the settlements of sub grade and sub soil should be within limits.
![Page 29: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/29.jpg)
RAILWAY FORMATION BEHAVIOUR
• Formation behaviour is not only
dependant on axle loads but also on
traffic density & pattern of traffic
• Therefore, simple bearing capacity
formula not applicable.
![Page 30: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/30.jpg)
SUBGRADE
• Main function is to provide a stable foundation for the blanket & ballast layers
• The influence of the traffic induced stresses extends downward as much as five metres below the bottom of the sleepers
• Hence, the subgrade is a very important and has a significant influence on track performance.
![Page 31: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/31.jpg)
Various Aspects of Designing Subgrade/Subsoil • Subgrade and Subsoil should be designed to be safe
against shear failure & large deformation.
• Deficient shear strength of sub-grade and sub-soil:
– Bearing cap, failure of sub-grade causing cess & crib heave, ballast pockets
– Interpenetration failure or mud pumping failure
– Slips in bank slopes or creep deformations
• Large deformation without strength failure due to :
– Swelling & Shrinkage characteristics of bank soil/sub soil.
– In-service compaction & consolidation of bank-soil/sub soil
![Page 32: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/32.jpg)
![Page 33: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/33.jpg)
![Page 34: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/34.jpg)
![Page 35: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/35.jpg)
SUB GRADE PARAMETERS
• Usually side slope 2:1 up to 6.0 m height
• Calculate Factor of safety of slopes– High banks>6.0 m– Poor sub soils including marshy soils– Water table is high (submerged weight)– Long term stability in cuttings
![Page 36: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/36.jpg)
SUB GRADE PARAMETERS
• Unsuitable soils for construction – Organic clay, silts & peat; chalks, dispersive
soils– Poorly graded gravel and sand Cu<2– CH and MH in top 3 m bank
• Special Investigations and remedies if to be done including cutting through shales and soft rocks which disintegrate with water
• Mixed Soils and Boulders – Care to be taken
![Page 37: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/37.jpg)
SUB GRADE PARAMETERS• Top width - 6.85 in filling & 6.25 in
cutting
• Cess width > 900 mm + additional on curve
• Top slope 1 in 30
• Erosion control
• Borrow Pit – away from toe
• Highly cohesive – special treatment
• Minimum height of bank - 1.00m
![Page 38: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/38.jpg)
BLANKET • The layer between the ballast & the sub grade is
the blanket• Functions :
1. Reduce stress to subgrade2. Keep subgrade & ballast separate3. Prevent upward subgrade fines migration4. Prevent subgrade attrition by ballast 5. shed water from above6. Drain water from below
• Ballast fulfills function (1) only• Blanket fulfills all functions and including
function (1), it reduces the otherwise required greater thickness of the ballast.
• In the absence of a blanket layer a high maintenance effort can be expected
• In addition, blanket dampens vibration.
![Page 39: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/39.jpg)
PROPERTIES OF BLANKET MATERIAL • Reduce stress to subgrade :• To serve as a structural material, it must have a
- High enough resilient modulus– Stable plastic strain accumulation characteristic
under repeated wheel load
• To achieve these properties – The material must be permeable enough to avoid
significant positive pore pressure build up under repeated load
– Must consist of durable particles– Must not be sensitive to changes in moisture content
![Page 40: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/40.jpg)
PROPERTIES OF BLANKET MATERIAL (CONTD.)
• SUBGRADE ATTRITION PREVENTION: – High stresses at the ballast contact points
on the subgrade surface are eliminated by the cushioning effect of the blanket
• DRAINAGE: PLAYS TWO ROLES– SHED WATER ENTERING FROM
SURFACE• Its permeability should be smaller than
that of ballast & have a surface sloped for lateral drainage
![Page 41: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/41.jpg)
•Drain water seeping up from the subgrade
To satisfy both roles, the sub-ballast must generally have a permeability between that of the subgrade & that of the ballast•This requirement probably will be achieved just by satisfying the separation criteria. However, an addl. Criterion is used to ensure adequate permeability to drain an adjacent layer :
D15(filter) > 4 to 5 D15 (soil being drained)
![Page 42: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/42.jpg)
•% FINES(PASSING 75µ) UPTO 5% PLASTIC FINES & UPTO 12% NON-PLASTIC FINES.• NO SKIP GRADING, COARSE GRAINULAR & WELL GRADED & MORE OR LESS WITHIN ENVELOPING CURVE•THE MATERIAL –WELL GRADED WITH Cu & Cc AS BELOW:
- uniformity coefficient, Cu = D60 /D10 > 4 (preferably >7)- coefficient of curvature, Cc = (D30)²/D60 /D10 within 1& 3
SPECIFICATION OF BLANKET MATERIAL
![Page 43: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/43.jpg)
REQUIRED BALLAST/BLANKET DEPTH • A min. ballast layer thickness is needed to provide
for maintenance tamping & for void storage space • A min. sub-ballast layer thickness is required for
performing the functions of a separation/filter layer• In addition, the combined ballast/blanket thickness
must be sufficient to prevent progressive shear subgrade failure, and excessive rate of settlement through plastic strain accumulation in the sub-grade
• As per RDSO guide lines, thickness of blanket required is 0 to one meter as per soil used in top one meter of subgrade & Axle load.
![Page 44: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/44.jpg)
DEPTH OF BLANKET LAYER • For axle load upto 22.5 t for different types of
subgrade soils (in top one meter)– No need of blanket for soilsRocky beds except shales & other soft rock,
which are susceptible to weathering or becomes muddy on contact with water
GW – well graded gravelSW – well graded sand Soil confirming to blanket materialSoil having grain size distribution curve lying
on right side of enveloping curve of blanket material in consultation with RDSO
![Page 45: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/45.jpg)
DEPTH OF BLANKET LAYER CONTD.
• 45 cm thick blanket for soils – GP having Cu > 2– SP having Cu > 2– GM– GM-GC
• 60 cm thick blanket for soils– GC– SM– SC– SM-SC– Should increase to one meter if PI > 7
![Page 46: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/46.jpg)
DEPTH OF BLANKET LAYER CONTD.
• 100 cm thick blanket from soils– ML– ML-CL– CL– MI– CI– Rocks which are very susceptible to
weathering
![Page 47: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/47.jpg)
DEPTH OF BLANKET LAYER CONTD.
• Soils having fines between 5 to 12% having dual symbol e.g. GP-GC, SW-SM etc. provide thickness as per second symbol
• Geo – synthetics can be used in consultation with RDSO as it reduced requirement of thickness of blanket.
• Blanket should be provided in new construction on all lines (even with light passenger traffic)– In cohesive sub grade even 100 cycles of
repeated load in excess of threshold strength will cause failure of formation.
![Page 48: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/48.jpg)
DEPTH OF BLANKET LAYER CONTD.
• In case more than one type of soil in top one of sub grade, soil requiring higher thickness of blanket will govern.
• For other types of soils not covered above, RDSO may be consulted for deciding thickness of blanket
• For higher axle loads – Above 22.5t up to 25 t- Add 30 cm thickness over
& above as given for 22.5 t– Above 25 t up to 30t - Add 45 cm thickness over &
above the given for 22.5t
![Page 49: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/49.jpg)
Day 2
![Page 50: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/50.jpg)
EXECUTION OF FORMATION EARTHWORKEXECUTION OF FORMATION EARTHWORK
• Before actual execution, details drawings to be prepared for entire length of the Project giving – Alignment
– Formation levels
– Formation width at ground levels
– Cross-sections of catch water drain & side drains
– Cross section & levels of sub-grade, blanket levels etc.
![Page 51: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/51.jpg)
• Good Practices for execution of earthwork• Preliminary work• Preparation of Natural ground
– Site should be cleared properly for full formation width at Ground level plus one metre
– Benching should be provided on ground having steep slope
• Setting out of construction Limits –Centre line of alignment (@200 m c/c or
so) and full construction width be demarcated with reference pegs about 90 cm away from proposed toe of bank.
![Page 52: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/52.jpg)
• Selection of Borrow area–Sufficiently away from alignment
–Normally not less than 3 m plus height of embankment
–Selected having soil reliable for construction
–OMC & MDD should be checked in Lab
![Page 53: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/53.jpg)
– General aspects
– Field trial for compaction test be done to access
• Optimum thickness
• Optimum number passes for type of roller
planned
– Soil should be wet/dried out to get required
OMC
– Clods or hard lumps to be broken to 75 mm
lesser size
– Each layer to be compacted with specified roller
commencing from sides up to required level of
compaction before putting next layer.
![Page 54: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/54.jpg)
COMPACTION • Compaction – Process of packing soil particles by
mechanical means increasing the dry density, decrease of voids
• Consolidation : Gradual process of vol. Reduction under sustained loading
• Compaction : Rapid reduction mainly in air voids under a loading of short duration viz. blow of a hammer, passing of a roller, vibration.
• Advantages of compaction : – Increase in shear strength– Reduction in deformation under traffic– Reduction in shrinkage & swelling– Reduction in permeability– Reduction in construction time.
![Page 55: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/55.jpg)
FACTORS AFFECTING COMPACTION • Compacting effort – Higher the effort greater the
compaction. • Water content : Lubrication action increase in dry
density till OMC. • Type of soil : Fine grained soils give lower dry
density than coarse grained soils– Well graded soils have higher dry density than
poorly graded soils– Plastics fines have marked effect on compactibility
• Other factors : – Thickness of lift– Contact pressure– Speed of rolling.
![Page 56: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/56.jpg)
FIELD COMPACTION EQUIPMENTS • Three classes : Rollers, rammers & vibrators
• Smooth wheel rollers : – 3 wheel or 2 wheel type – best suited for gravel, sands, crushed rocks and
any material requiring crushing action.
– More no. of passes, more compaction.
![Page 57: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/57.jpg)
• Sheep’s foot Rollers : – Numerous projections
known as feet.– Kneading action from
bottom upwards– When fully compacted
no foot penetration– Suitable for cohesive
soils at low OMC.– Unsuitable for gravels,
sands– More no. of passes
more compaction.
![Page 58: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/58.jpg)
• Pneumatic Rollers
– Compaction effort depends on weight, tyre dia & inflation pressure.
– Both pressure & kneading action
– Suitable for cohesive soils at high natural m/c.
– Cohesion less sands and gravels.
![Page 59: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/59.jpg)
• Vibratory Rollers : – Out-of-balance weight type or pulsating
hydraulic type– Frequency between 1000-3000 rpm. – Suitable for granular soils – Allow compaction to a higher depth. – Not suitable for cohesive soils.
• Rammers : – Pneumatic or internal Combustion type. – Suitable in area with restriction working
space.
![Page 60: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/60.jpg)
ADVANTAGES OF COMPACTED BANK
• Higher speed of opening.
• Opening to goods & pass. Traffic simultaneously
• Max. sectional speed can be achieved in shortest time
• Ballast can be laid directly
• LWR can be laid
![Page 61: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/61.jpg)
MEASUREMENT OF FIELD COMPACTION • determining dry density of soil in-situ
methods : – Sand replacement
• Any type of soils • slow method
– Core cutter • Fine grained cohesive soil • convenient method
– Water displacement • only cohesive soils
– Nuclear • In-situ density & w/c
![Page 62: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/62.jpg)
• Placement of Back-fills on Bridge approach– Back fills resting on natural ground may cause
differential settlement, vis-a-vis abutment, which rest on comparitively much stiffer base
– Back fill should be designed carefully to keep• Settlement within tolerable limits• Coefficient of subgrade reaction should have
gradual change from approach to bridge.– Backfills on bridge approaches shall be placed in
accordance to para 605 of Indian Railways Bridge Manual 1998.
![Page 63: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/63.jpg)
– Fill material being granular and sandy type soil be placed 150 mm on lesser thick layers & compacted with vibratory plate compactors.
– Benching should be made in approach embankment to provided proper bonding.
![Page 64: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/64.jpg)
SKETCH SHOWING BACKFILL DETAILS
![Page 65: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/65.jpg)
IMPORTANCE OF BACKFILL• IMPORTANCE OF BACKFILL GENERALLY NOT UNDERSTOOD.• MAGNITUDE OF LATERAL EARTH PRESSURE DEPENDS ON:
- angle of internal friction – the more the value of ø, the lesser is the magnitude ( table below )
- density- presence of water may increase earth pressure upto 250%
• COHESIONLESS MATERIAL: - provide effective drainage. - value of ø is more.
Grain size Values of Ø in degree
Clay
Sand & Gravel
Blasted rock fragments
30 ( Generally 20)
32 – 41
40 - 50
![Page 66: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/66.jpg)
• Drainage arrangement in banks & cutting
– Effective drainage of rainwater in monsoon is
very important to safe guard subgrade from
failure
– Drainage of embankment
• Cross slope is provided from centre towards
end.
• No side drains required except in case blanket
layer goes below natural ground level
• On double line, central drain should be
avoided as far as possible.
![Page 67: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/67.jpg)
– Drainage in Cuttings• Side drains
–Required water carrying capacity side drains be provided on both sides except where height of cutting is less than say upto 4 m.
–In deep cuttings, catch water drains of adequate capacity are required along with side drains.
![Page 68: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/68.jpg)
![Page 69: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/69.jpg)
• Catch Water Drains
Required to control huge quantity of water coming
from hill slope in cutting from safety consideration
Catch water drains should be made pucca/lined
with impervious flexible material locally available
Catch water drains should be designed properly
with - Adequate slope
–No weep hole
–Sealing of expansion joint
–Regular inspection & maintenance
–Proper protection against tail end erosion.
![Page 70: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/70.jpg)
CATCH WATER DRAIN
![Page 71: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/71.jpg)
LOWERING OF GROUND WATER IN A WET CUT
![Page 72: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/72.jpg)
• Erosion control of slopes on bank/cutting– Exposed surface of bank/cutting
experiences surfacial erosion due to action of wind & water
– Erosion control measures are commonly classified into following four categories..
– 1)Conventional non-agronomical system• This system uses asphalting, cement
stabilization pitching etc.• System is best utilized against seepage,
erosion by wave action etc.
![Page 73: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/73.jpg)
– 2) Biotecnical system• Vegetation is provided on exposed surface• Best suited for soils having some clay
fraction, • Suitable grass used are doob grass, chloris
gyne, Inponea gorneas, casuariva & goat foot creepers, vetiver grass etc
– 3)Engineering System• Geo-jute
–Used in areas having high erosion–Biodegradable & helps in growth of
vegetation on degradation–Two types – fast/slow biodegradable.
![Page 74: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/74.jpg)
– 4) Polymer geogrids• Used under unfavorable soil & rainfall
condition where vegetative growth is difficult• Flexible, non biodegradable. Resistant to
chemical effect, ultraviolet degradation resistant & stable over a temperature of 60-1000C
– Hydro-seeding system • Non-conventional & innovative system of
development of vegetation• Verdyon mulch solution @ 100 to 150 gm/m2
is sprinkled on surface from germination of vegetation as per local soil/climatic condition.
![Page 75: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/75.jpg)
SHOTCRETING
![Page 76: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/76.jpg)
PITCHING
![Page 77: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/77.jpg)
RETAINING WALL
![Page 78: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/78.jpg)
GABIONS
![Page 79: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/79.jpg)
![Page 80: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/80.jpg)
ROCK BOLTING
![Page 81: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/81.jpg)
SOIL NAILING
![Page 82: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/82.jpg)
BOULDERNETS OF GEOSYNTHETICS
![Page 83: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/83.jpg)
BOULDERNETS OF GEOSYNTHETICS
![Page 84: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/84.jpg)
CATCH FENCING
![Page 85: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/85.jpg)
• Other important aspects
• Suitable slope be provided during rolling to avoid ponding of water
• Top slope 1 in 30 way from centre• Extra wide bank by 500 mm on either side &
then cut & dressed to avoid loose earth on shoulders
• Minimum overlap of 200mm between each run of roller
• At the end of working day, fill material should not be left uncompacted.
• Rain cuts should not be allowed to developed deep and wide.
![Page 86: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/86.jpg)
• After finishing formation movement of vehicles should not be allowed on top.
• In conversion/doubling/rehabilitation projects, suitable benching of existing slopes be done before new earthwork is taken up.
• 30cm granular base be provided where water table is high & fill material is fine grained.
• At places where embankment material are not conductive to plant growth, top soils from site clearance/cutting/borrow pits be stored for covering slopes of embankment/cutting.
![Page 87: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/87.jpg)
• WIDENING OF EMBANKMENT -
• Uproots vegetation, remove loose materials.
• Benching at every 30cm ht.
• E/w in layers. Each layer sloping out 1:30.
• Compaction by using vibrating rollers of around
900mm wide.
• 6 to 8 passes normally sufficient
• 98% of MDD or equal to existing bank.
• Density to be checked at 200m length.
• Width of each layer in excess by 300mm.
• Excess width to be cut and dressed
![Page 88: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/88.jpg)
![Page 89: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/89.jpg)
• RAISING OF EXISTING FORMATION -
• Raising to be done after widening.• Raising <150mm, with ballast restricting overall
thickness to 350mm.• Raising 150mm to 1000mm,
• existing ballast to be taken out• granular material to be provided• top 600mm of granular material shall satisfy
the specifications of blanket & compacted • thereafter clean ballast to be inserted.
• Raising >1000mm, desirable to lay a detour temporarily.
• EARTHWORK IN DETOURS• In accordance with RDSO’s guidelines.
![Page 90: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/90.jpg)
• EMBANKMENT ON SOFT SOIL– Soil shall be improved using
• Preloading and stage construction as per the design.
• Installation of vertical sand drains.• Installation of prefabricated vertical drains.
– Selection of particular scheme depends on rate of construction & techno-economic consideration.
– This may be decided in consultation with RDSO.
![Page 91: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/91.jpg)
• SANDWICH CONSTRUCTION OF BANK WITH COHESIVE SOILS– May be adopted with cohesive soils having
very low permeability (< 10-2 cm/sec) & bank height more than 3m.
– A layer of coarse sand (Cu > 2) of about 20 to 30 cm be provided at interval of 2 to 3 m.
– Even up to 3 m bank height, a bottom layer of sand be provided
– Before adopting such construction a detail techno-economic study be carried out if required, RDSO be consulted.
![Page 92: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/92.jpg)
![Page 93: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/93.jpg)
• Safety at work site– Necessary precaution towards safety at
work site including doubling & gauge conversion should be part of contract agreement
• Environmental aspect– Efforts should be made to ensure least
disturbance to surrounding environment– Rules & regulations of Govt. be followed in
this regard
![Page 94: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/94.jpg)
QUALITY ASSURANCE OF EARTHWORK
• Adequate quality control/checks at all stages of construction be carried out– Selection of construction material– Adoption of Method– Use of suitable machinery– During execution of work.
• Setting up of GE lab field lab– No. of GE field labs be set up as per requirement of
project/work site– Aspects to be looked after by GE lab
• Ensure quality of supplied soil and blanket material• Evaluate method of compaction by conducting test• Exercise moisture and density control
![Page 95: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/95.jpg)
– Depending on requirement, field lab to be equipped with minimum equipment to ensure following minimum tests
• Gradation Analysis – Sieve and Hydrometer• Atterberg’s limits – Liquid limit & plastic limit• OMC, MDD & Relative density• Placement moisture content & insitu Density
![Page 96: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/96.jpg)
• QUALITY CHECKS ON EARTHWORK– Quality control on construction Material
• To ascertain suitability of material• To decide OMC & MDD for quality control
inputs for compaction control• These tests to be done for both borrow
material & blanket material • Frequency of Testing of site
– Borrow material• One test at every change in strata• Minimum one test for every 5000 cum
– Blanket Material• Minimum one test for every 500 cum or part
thereof
![Page 97: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/97.jpg)
• Quality control checks on finished earthwork– Compacted earth
• Method of sampling• Acceptance criteria
–All types of soil & when compacted – »by dry density 98% of Max. Dry
density.–During widening/gauge
conversion/rehabilitation work»98% of MDD or»70% of relative density
![Page 98: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/98.jpg)
• Frequency of testing–For blanket/top one meter of subgrade
»One check for every 200 sqm–For other places
»One check for every 500 sqm–At special locations closer frequency
may be adopted–Bank widening
»One check at every 200m
![Page 99: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/99.jpg)
Method of sampling• DEGREE OF COMPACTION OF EACH LAYER ASCERTAINED BY MEASUREMENT OF DRY DENSITY / RELATIVE DENSITY OF SOIL AT LOCATIONS SELECTED IN SPECIFIED PATTERN SHOWN BELOW.
NOTE: x & y AS PER SAMPLING AREA RQUIREMENT
![Page 100: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/100.jpg)
– Formation level• Subgrade 25mm• Blanket +25mm
– Cross slope• 1 in 28 to 1 in 30
– Side slope• Should not be steeper than design
– Formation width• Should not be less than specified
)(
![Page 101: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/101.jpg)
MAINTENANCE OF RECORDS
• Quality control Records – Characteristics of borrow materials– Quality of blanket materials– Field compaction trials– Quality of compaction of earthwork including
blanket material
• Quality of material & its compaction of backfill behind bridge approach etc.
![Page 102: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/102.jpg)
• Details of machineries engaged in execution of earthwork including output as per Performa decided by field engineers
• Permanent Records– Desirable to prepare completion drawing of
embankments and cutting including special features like• Toe walls• breast walls• Catch and side drains• Cross section of embankments/cutting• Type of soil in subgrade• Depth of blanketing material• Geological features.
![Page 103: What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the track. It is important constituent of the track as it](https://reader038.vdocuments.us/reader038/viewer/2022103100/56649ec15503460f94bcdc62/html5/thumbnails/103.jpg)
THANK YOU