What is formation? Formation is a prepared flat surface, which is ready to receive ballast of the...

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.

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.

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.

DEFINITIONS

BLANKET

SUB - GRADE

TRACK- FOUNDATION

TRACK STR.

FORMATION

B A L L A S T

CESS

SUB - SOIL

Classification of soil

Good soils Coarse grained soil

Other than Good soils

Fine grained soils such as silts sandy and silty clays

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

SOIL – THE SUPPORT SYSTEM

• Mother Earth.

• Has it unlimited Capacity?

• Appears simple but least understood.

• Mostly taken for granted.

SOIL?????

• What is Soil?– Residual– Transported

• Soil Mechanics

• Geotechnical Engineering

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

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

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

PARTICLE SIZE DISTRIBUTION

D10 – Effective size

Coefficient of uniformity - Cu

Cu=D60/D10

Coefficient of Curvature Cc

Cc=(D30)2/D60XD10

D60D30D10

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

LIQUID LIMIT - ATTERBERG’S LIMITS

Liquid Limit is the water content at which 25 blows cause the groove to close.

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

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

COMPACTION – Primarily Expulsion of Air

COMPATION OF SOILS

18”4.54 Kg

γd = γ/(1+w/100)ID = {(emax-e)/(emax-emin)}x100

ID - Relative density – cohesion less soils

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

SOIL SURVEYS

• RECONNAISSANCE SURVEY

• PRELIMINARY SURVEY

• FINAL LOCATION SURVEY

RECONNAISSANCE SURVEY

• General Idea

• No laboratory tests

• Other Surveys, topological maps, geological

• Visual Inspection

• Behaviour of existing structures

• Prospective Borrow Area - Soil & Blanket

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

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

• 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.

• 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.

FORMATION IN BANK

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.

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.

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.

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

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

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

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

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.

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

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

•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)

•% 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

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.

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

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

DEPTH OF BLANKET LAYER CONTD.

• 100 cm thick blanket from soils– ML– ML-CL– CL– MI– CI– Rocks which are very susceptible to

weathering

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.

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

Day 2

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.

• 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.

• 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

– 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.

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.

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.

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.

• 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.

• 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.

• 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.

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

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

• 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.

– 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.

SKETCH SHOWING BACKFILL DETAILS

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

• 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.

– 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.

• 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.

CATCH WATER DRAIN

LOWERING OF GROUND WATER IN A WET CUT

• 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.

– 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.

– 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.

SHOTCRETING

PITCHING

RETAINING WALL

GABIONS

ROCK BOLTING

SOIL NAILING

BOULDERNETS OF GEOSYNTHETICS

BOULDERNETS OF GEOSYNTHETICS

CATCH FENCING

• 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.

• 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.

• 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

• 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.

• 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.

• 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.

• 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

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

– 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

• 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

• 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

• 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

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

– 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

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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.

• 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.

THANK YOU