3c64ad12 Bfd2 4446 b56a 2d26a65b469f Bidding Document Transmission

8/10/2019 3c64ad12 Bfd2 4446 b56a 2d26a65b469f Bidding Document Transmission

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on the foundation pad with the sides of the pyramidal cone of earth at an angle equal to the angle of repose of the soil with


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vertical. The weight of concrete including reinforcement shallalso be considered for resisting the uplift. In case the frustumof earth pyramid of two legs superimpose each other, the earthfrustum shall be assumed truncated by a vertical planepassing through the centre line of the tower base. The angle of internal friction and density of various types of soils and theproperties of concrete are given in Section-II of theSpecification.

(ii) RESISTANCE AGAINST COMPRESSION FORCE/DOWNTHRUST:

The total compression force/down thrust load includingadditional effective weight of concrete and weight of embeddedsteel parts shall be resisted by limiting bearing pressure of thesoil acting on contact area of footing with soil. The limitingbearing pressures for various types of soil likely to be

encountered enroute the 132 kV D/C line are given inSection-II .

(iii) RESISTANCE AGAINST THE SIDE THRUST:

The horizontal shears / side thrusts shall be assumed to beresisted by the passive pressure of soil around the footing

considerations. Slab type R.C.C. footings shall be provided atlocations where, from techno-economical considerations, pyramid


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types of foundations are not acceptable.

1.27.8.3 Seismic Forces: Design of foundations for towers against seismicforces shall conform to IS: 1893-2002 and other InternationalPractices. The importance factor to be considered in the calculationof seismic forces shall be 1.5 and other factors shall be as perabove code. In the event of award of contract, detailed supportingdesign calculations regarding adequacy and safety of foundationsagainst seismic forces shall be furnished by the contractor.

1.27.8.4 All foundations shall be designed so as to satisfy and meet thefollowing requirements:

(a) The chimney of the foundation shall at least be 300 mmsquare providing a minimum clear concrete cover of not lessthan 100 mm to any part of the stub angle in case of dry foundations and at least 400 mm square with minimum

clear concrete cover of not less than 150 mm to any part of the stub angle in case of wet, partially submerged and fully submerged foundations.

(b) The chimney top shall extend 300 mm (Minimum) aboveground level inclusive of coping and coping shall be up to50 mm below the joint between the bottom bracing and the

(f) The depth of foundation below ground level shall not bemore than 3.0 m.


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(g) The joints between the tower stubs and the superstructurebracing members shall be 350 mm above ground level.

(h) The centroidal axis of the stub shall coincide with axis of the chimney and pass through the centre of the footingbase. The design of the foundation shall take into accountthe additional forces resulting from eccentricity introduceddue to non-compliance of above requirements.

(i) The chimney shall be designed as a composite member forcombined action of axial forces and bending moments. Themaximum compression/tension force along with momentsin both the directions due to horizontal shears viz.transverse and longitudinal shall be considered in thedesign of chimney. The adequacy of chimney section shallbe checked as per above and necessary reinforcement in

chimney shall be provided as per design requirement. Thechimney shall be designed as a composite section consistingof concrete, steel stub and reinforcement bars. The designshall be carried out as per limit state method of design inaccordance with IS: 456-2000. Irrespective of designrequirements, minimum reinforcement consisting of 0.15%of the cross sectional area of the chimney or 4 Nos of 12

(d) The grade of concrete used in Pyramid type foundation inchimney and Pyramid portion shall be M20.


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1.27.8.6 The slab type R.C.C. foundations shall also satisfy and meet thefollowing requirements is addition to requirement specified inClause 1.27.8.5 above:

(a) The structural design of foundations shall be strictly inaccordance with IS: 456-2000 and other relevant I.S.codes.

(b) The design of R.C.C. foundations shall be carried out by limit state method in accordance with IS: 456-2000, usingpartially safety factors as given in the clause 1.27.5.1.

(c) The minimum thickness of footing slab for foundationsshall not be less than 250 mm in case of dry locations and300 mm in case of wet locations.

(d) As specified in IS : 456-2000, the minimum thickness of footing slab at the edges shall not be less than 150 mm.

(e) In case of stepped foundations, the reinforcement at topface of each step shall be separately provided. Thereinforcement from one step to another step at top face of the footings shall not be permitted

1.27.8.8 PILE FOUNDATION:


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Pile foundation may be required at some tower locations especially located in flood plain of rivers where there are chances of scouringduring floods or at locations where bearing capacity of soil is very poor and shallow foundation cannot be provided.

Bored pile shall be provided in case pile foundations are foundnecessary. The design of Bored pile foundation shall be inaccordance with IS: 2911(Part - I). The pile foundation shall alsosatisfy and meet the following requirements:

(i) The minimum diameter of pile shall be not less than400mm.

(ii) The grade of concrete shall be minimum M-25.

(iii) The minimum clear cover to reinforcement shall be not lessthan 50mm.

(iv) The minimum spacing of piles shall not be less than 3.0times the diameter of pile.

(v) The minimum longitudinal reinforcement in the pile shaftshall not be less than 0.4% of the cross-section area of pileshaft.

(vi) The minimum diameter of main reinforcement bars shallnot be less than 16mm and minimum diameter of links

1.28 FABRICATION


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1.28.1 The fabrication of towers shall be in accordance with the provisionsmade in the following sub-clauses.

1.28.1.1 Except where here-in-after modified, details of fabrication shallconform to the relevant clauses of IS : 802(Part -II) -1990 or latestedition.

1.28.1.2 The Contractor during fabrication of tower members shall ensurethat mild steel and high tensile steel do not get mixed up duringfabrication and as such identification mark shall be embossed oneach and every H.T.Steel section at the time of shearing of members. The tenderer in his tender shall clearly bring out the meansadopted to identify the mild steel and high tensile steel sectionsduring fabrication.

1.28.1.3 All parts of the towers shall be cut to correct lengths and fabricatedin accordance with the shop drawings approved by the Purchaser.Welding of two or more pieces to obtain the length of memberspecified will not be allowed. Members shall be straight to thepermissible tolerances or better when required to ensure proper fitbefore being laid off or worked and after galvanising.

gusset, and it shall be connected at the point of intersection by oneor more bolts.


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1.28.1.7 The tower members shall be accurately fabricated to bolt togethereasily at site without any undue strain on them or the bolts.

1.28.1.8 No angle member shall have the two leg flanges brought together by closing the angle.

1.28.1.9 All parts of the towers shall be accessible for inspection andcleaning. Drain holes shall be provided at all points where pocketsor depressions are likely to hold water.

1.28.1.10 All similar parts shall be made strictly interchangeable. No roughedges shall be permitted any where throughout the work.

1.28.2.1 STRAIGHTENING:Straightening shall be so done that it does not injure the material.Hammering shall not be permitted for straightening / or flattening

of members. Sharp bends shall be a cause for rejection.

1.28.2.2. CUTTING : The cut surfaces shall be clean , smooth, reasonably square andfree from any distortion.

1 28 2 3 BENDING :

holes shall be maintained with the use of proper templates/jigsand fixtures. The limit of punching for H.T. Steel section may bei di d i h bid


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indicated in the bid.

1.29 FASTENERS : BOLTS, NUTS AND WASHERS

1.29.1 All bolts and nuts shall conform to IS: 6639-1990 and IS 12427-1988 or latest edition. All bolts and nuts shall be galvanised andshall have hexagonal head and hexagonal nut. The heads beingforged out of the solid truly concentric, and square with the shank,which must be perfectly straight ultimate stresses in the bolts shallbe as given in table - I of cl. 5.4.1 of IS 802(part I /Section 2 ) 3rdrevision.

1.29.2 Fully threaded bolts shall not be used. The length of bolts shall besuch that the threaded portion will not extend into the plane of contact of the member.

1.29.3 All bolts shall be threaded to take the full depth of the nut and

threaded for enough to permit firm gripping of the members, but notfurther. It shall be ensured that the threaded portion of each boltprotrudes not less that 3mm and not more than 8mm when fully tightened. All nuts shall fit and tight to the point where the shankof the bolt connect to the thread.

1 29 4 Flat and tapered washers shall be provided wherever necessary

1.29.8 Bolts at the joints shall be so staggered that nuts may be tightenedwith spanners without fouling.


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1.29.9 SPACING OF BOLTS AND EDGE DISTANCE :

The minimum spacing of bolts and edge distances shall be as givenbelow:---------------------------------------------------------------------------------------------Bolt Hole Minimum Minimum edgeDistance(mm)dia- dia- bolt Hole centre Hole centremeter meter spacing to rolled or to sheared(mm) (mm) (mm) sawn edge or flame cut edge---------------------------------------------------------------------------------------------

16 17.5 40 20 2320 21.5 48 25 2824 26.0 60 33 38

------------------------------------------------------------------------------------

1.29.10 LOCKING DEVICES

Electrogalvanised/hot dip galvanised spring washers of type B of thickness indicated below corresponding to bolt diameter shall beprovided for insertion under all nuts.

Bolt Thickness of Diameter spring washer

1.29.12.5 Tolerance on guage distance shall be within 0.5mm.


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1.30 ERECTION MARK

1.30.1 Each individual member shall have erection mark conforming to thecomponent number given to it in the fabrication drawings. Thismark shall be punched with marking dies of 16 mm size beforegalvanising and shall be legible after galvanising.

1.30.2 Erection Mark shall be A-BB-CC-DDDA = Purchaser's code assigned to the contractors-

Alphabet.BB = Contractor's Mark-NumericalCC = Tower Type-AlphabetDDD = Number mark to be assigned by Contractor-

Numerical.

1.31 CHECK ASSEMBLY OF TOWERS.

1.31.1 Before proceeding with the bulk fabrication of any type of tower, theContractor shall fabricate and assemble in his works for inspectionby the purchaser or his authorised representative, one tower of eachtype as finally approved by the Purchaser for checking thefabrication accuracy and workmanship. The check assembly shallbe in a horizontal position Proto assembly made on ground in

details of which shall be given in the tender) for protection againstwhite rust formation during sea transportation.


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1.33 STUB SETTING TEMPLATES

Stub templates shall be designed, fabricated and supplied by thecontractor for all types of tower with or without extensions and alsofor leg extension. Stub templates suitable for standard towers andtower with extension of 3 metre, 6 metre, and 9 metre shall be of adjustable type. The stub templates shall be painted withanticorrosive paints. The number of templates of each type of toweris to be arranged by the contractor to the satisfaction of thepurchaser for timely completion of line. The quantities of templatesindicated in the Schedule are required by the purchaser for keepingin stores.

1.33(a) Thickness of Stubs:The thickness of stub-section should be kept 2mm more than thethickness of the last leg members connected to the stub.

1.34 DRAWINGS AND BILL OF MATERIALS.

1.34.1.a The following technical drawings and documentation are to besubmitted along with the tender without which the tender is liableto be rejected:-

Dimensioned drawings for anti-climbing device.Loading diagram for all towers under different working conditions.Dimensioned drawings for foundations for each type of standard


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Dimensioned drawings for foundations for each type of standardtower, and tower with 3 metre, 6 metre, & 9 metre extensions with

detailed design computation resisting uplift, down thrust and sidethrust shall be furnished. Drawings shall show all details of keyingrods, cleat angles, etc. to be provided for concrete foundations.For foundations of each type of towers, the drawings shall furnishthefollowing information:-

a) Dimensions of excavation per leg.b) Volume of concrete.

The capacity charts for all types of towers to be used for smallerangles and longer spans shall be furnished after award of Contract.

1.34.2 Award of contract:- The contractor shall submit after placement of letter of award detailed designs of tower, extension, alongwithcomputer output together with sample calculations for few criticalmembers etc.A soft copy of input files of computer program used for

analysis of various type of towers shall also be supplied for chekingthe tower designs.

1.34.3 The design and drawings as covered in clause 1.34.1.b. above shallbe approved/commented by the owner as the case may be with inthirty (30) days of receipt of designs/ drawings in Chief Engineer'soffice If the designs/drawings are commented by the owner the

d) Bill of Materials: A complete bill of material for each type of tower shall be submitted with the erection drawingsindicating each part number required quantities for one


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indicating each part number, required quantities for onetower section of member length, calculated weight and

relevant design drawing reference.e) Bolts, Nuts and washer Schedule: Bolts, nuts and washers

schedules shall list the number of bolts and washersrequired per tower alongwith the sizes and lengths of boltsand number, type and size of washers. The shank lengthand length of threaded portion of various types of boltsshall be indicated in drawing / table.

1.35 TESTING OF TOWERS

1.35.1 All standard tests, including quality control tests in accordancewith relevant Indian Standards shall be carried out.

1.35.2 1.35.2 An ungalvanised (black)tower of each type complete with9m extension shall be subjected to design and destruction tests by

first applying test loads equivalent to the specified ultimate towerloadings and applied in a manner approved by the purchaser. Thetower shall withstand these tests without showing any sign of failureor permanent distortion in any part. Thereafter the tower shall besubjected to destruction by increasing the loads further in anapproved manner till it fails. The tower shall be tested for all theconditions considered for the design of tower The successful Bidder

inspection of materials during manufacturing stage and also duringtesting of the same.


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1.35.4 In case of any premature failure even during waiting period, the

tower is to be retested with rectified members. However, if thefailures are major in nature and considerable portion of tower is tobe re-erected, in such cases all the tests which has been carried outearlier to be reconducted again to the entire satisfaction of Purchaser.

1.35.5 No part of any tower subject to test shall be allowed to be used onthe line. The price will be quoted after allowing rebate for the scrapvalue of the tower material which will be retained by the successfulBidder.

1.35.6 The Contractor shall ensure that the specification of materials andworkmanship of all towers actually supplied conform strictly to thetowers which have successfully under gone the tests. In case any deviation is detected the Contractor shall replace such defective

towers free of cost to the Purchaser. All expenditure incurred inerection, to and fro transportation, any other expenditure or lossesincurred by the Purchaser on this account shall be fully borne by the successful Bidder. No extension in completion time shall beallowed on this account.

The Purchaser however reserves the right to waive off the testing of

of the test. The decision of the Purchaser's representative regardingwhich member and number of members to be tested is final andbinding The successful bidder shall make suitable arrangement for


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binding. The successful bidder shall make suitable arrangement forthe same.

1.35.11 Prefix 'T' shall be marked on all members of test tower in addition tothe mark no. already provided.

1.35.12 Calibration of Measuring Instruments

All measuring instruments shall be calibrated atleast 20% above themaximum anticipated load to be applied during testing with the helpof standard weights. The test loads shall be corrected with the helpof calibration curves.

1.35.13 TESTS

The procedure for conducting the tower test shall be as specified inIS: 802 (Part - III) (latest edition).

1.35.13.1 BOLT SLIP TEST :

The test loads shall be gradually applied upto the design loadsaccording to rigging diagram, kept constant for two(2) minutes at thedesign loads and then released gradually. The initial and finalreadings on the scales before application and after the release of

For normal as well as broken-wire tests, the tower shall be keptunder observation for five minutes with 100% ultimate design loadapplied to it


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applied to it.While the loading operations are in progress, the tower shall be

constantly watched and if it shows any tendency of failureanywhere, the loading shall be immediately stopped, released andthen the entire tower shall be inspected. The re-loading shall bestarted only after corrective measures are taken.

The deflection of the tower shall be recorded at each intermediateand final stage of normal load/ broken - wire load test by means of atheodolite and graduated scales fitted on the tower. The structuresshall be considered to be satisfactory if it is able to support thespecific ultimate load for five(5)minutes with no visible deformationafter unloading (such as bowing, buckling )and no breakage of elements or constituent parts. Ovalization of holes and permanentdeformation of bolts shall be considered as failure.

1.35.13.3 Destruction Tests : If desired by the purchaser, all types of towers

shall be tested to destruction. The test shall be carried out undernormal condition. All the provisions as stated in clause 1.35.13.2shall be applicable to destruction test. However, the loads shall beincreased in steps of 5% after the ultimate design loads have beenreached.

1 35 13 4 Material Test : In case of failure of towers after retest coupons shall

steel wire with ends twisted tightly. Gross weight of any bundleshall not exceed approximately 450 kg.


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1.36.3 Cleat angles, brackets , fillet plates and similar small loose pieces

shall be nested and bolted together in multiples , and securely wired together through holes, wrapped round at least four timeswith No.9 guage galvanised steel wire and ends twisted tightly.Gross weight of each bundle shall not exceed approximately 70kg.

1.36.4 The correct number of bolts, nuts and washers to be packed inheavy gunny bags accurately tagged in accordance with the contentsand a number of bags packed in a solid box of 22mm thick lumberwith panelled ends to be securely nailed and further reinforced with22mm x No. 18 guage iron band stretched entirely around thebattons with ends over lapping at least 150mm. Gross weight of each box shall not exceed approximately 70kg.

All packing shall be subject to the approval of the Purchaser, or hisappointed representatives.

The packing shall be carried out with caution to protect the materialfrom moisture, salt or any impurities which may cause rust orharmful effects.

The packages shall be new and sufficiently sturdy in construction towithstand normal service incident to shipping and field handling

shall be stated in the Schedules in Section III,and shall not bechanged without the approval of the Purchaser. The tenderer shallalso submit the details of manpower available with his Organisation


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also submit the details of manpower available with his Organisationindicating clearly the number of personnels engaged in the design,

fabrication of supporting structures and for erection/construction of the transmission lines. The tenderer shall give a brief profile of theOrganisation(s)

1.39 GUARANTEED TECHNICAL PARTICULARS

1.39.1 The tenderer shall fill in the guaranteed technical particulars in theSchedule-A in section-III of this Specification and submit the samewith tender.

1.40 SCHEDULE OF REQUIREMENTS AND DESIRED DELIVERY

1.40.1 The schedule of requirements (tentative ) and desired deliveries isgiven in Section -II of this Specification.

1.41 PERFORMANCE SCHEDULE

1.41.1 The tenderer shall furnish the details of his performance in respectof the major works carried out by him involving supplies of materialsfor and/or erection of such EHV lines preferably 132 kV lines whichare in service, at least for the last five years, in the performanceschedule contained in Section - III of this Specification

1.44 PAYMENTS

The payments towards supply of tower part shall be in accordance


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The payments towards supply of tower part shall be in accordancewith the section General Condition of Contract(GCC) and of section

Special Condition of Contract (SCC) of volume I of this specification.

CHAPTER-2SURVEY


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2.1 SCOPE

2.1.1 This chapter covers finalisation of alignment of the transmissionlines, detailed survey, route profile, tower spotting and soil testingfor determining the characteristics of soils at selected locations fordesign of foundation along the transmission lines route.

2.2 TRANSMISSION LINE ROUTE

2.2.1 The proposed route of the transmission lines is shown in exhibit-I. The contractor shall examine the proposed route from the undermentioned considerations and prepare the route alignment mapindicating clearly the changes, if any, considered necessary by thecontractor in the interest of economy/better alignment for theapproval of the purchaser.

a) The lines are near to and along the available roads in the area.b) The route should be as short and as straight as possible.

c) The number of angle towers should be minimum and withinthese the number of heavier angle towers shall be as small aspossible.

d) G d f i t i li i l i il d

2.3 DETAILED SURVEY

2.3.1 The Contractor shall submit the proposal for detailed route survey


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.3. p p ybased on approved preliminary route alignment. The contractor shall

finalize and submit proposal for all obligatory points within three (3)months from the date of commencement of work at site. Theseobligatory points shall include all the River crossings, Railway Crossings, Power Line Crossings or any other important crossingsencountered in the transmission line route. The following scheduleshall be adhered to in respect of obligatory points:

Submission of proposal andprofile to WAPCOS/ CEA

3 months from the date of award of contract i.e. date of receipt of advance

Submission of soil investigationReport

1 month from the date of approvalof profile.

The Bidder should note that Owner will not furnish thetopographical maps prepared by Survey of India but will makeavailable any assistance that may be required in obtaining thetopographical maps.The detailed survey shall be made along the approved alignment

2.5 PROFILE PLOTTING AND TOWER SPOTTING

From the field book entries, the route plan with reroute details and


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, plevel profile shall be plotted and prepared to scales of 1 : 2000

horizontal & 1 : 200 vertical on 1.0, 10 mm squared paper as perapproved procedure. Reference levels at every 20 meters along theprofile are also to be indicated on the profile besides, R/Ls atundulations. Areas along the profile which, in the view of thecontractors, are not suitable for tower spotting, shall also be clearly marked on the profile plots. If the difference in levels be too high thechart may be broken up according to requirement. A 10 mm overlapshall be shown on each following sheet. The chart shall progressfrom left to right. Sheet shall be 594 mm wide in accordance withthe IS Standard. For as built profiles these shall be in A1 size.

2.6 TOWER LOCATION

2.6.1 SAG TAMPLATE

Sag template drawing will be prepared and submitted by thecontractor at the time of detailed survey for approval of theWAPCOS/ CEA. Based on the above drawing, the Contractor has toprepare sag template on rigid transparent plastic sheet and providetwo sets of the same to Owner for checking purpose.

2 6 2 TOWER SPOTTING

shall support at least the minimum weight span as providedin the designs. In case uplift is unavoidable, it shall beexamined if the same can be overcome by adding standard


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y gbody extension to the towers failing which tension towers

designed for the purpose shall be employed at such positions.

d) Road CrossingAt all important road crossings, the towers shall be fittedwith normal suspension or tension insulator stringsdepending on the type of towers but the ground clearance atthe roads under maximum temperature and in still air shallbe such that even with conductor broken in adjacent span,ground clearance of the conductor from the road surfaces willnot be less than 6.10 meters. At all national highways,tension towers shall be used. The crossing span, howeverwill not exceed 250 meters in any case.

e) Railway CrossingsRailway crossings shall be supported on B, DB type or C, DC

type or D, DD type towers on either side, depending on themerits of each case and shall be constructed in conformity with the specification laid down by the Railway Authorities.Necessary copies of tracings and prints of plan, profile etc.,required for the approval of railway crossings shall besupplied by the Contractor to the Owner free of cost.In case of rail crossing the minimum height above rail level of

g) Telecommunication Line Crossing The angle of crossing shall be as near to 90 0 as possible.However, deviation to the extent of 30 0 may be permitted


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y punder exceptionally difficult situations.

When the angle of crossing has to be below 60 o , the matterwill be referred to the authority in charge of thetelecommunication system. On a request from theContractor, the permission of the telecommunicationauthority will be obtained by the Owner. Also in thecrossing span, power line support will be as near thetelecommunication line as possible, to obtain increasedvertical clearance between the wires.

h) Details EnrouteAll topographical details, permanent features, such as trees,building etc.,13.5 m on either side of the alignment shall be detailed onthe profile plan.

2.7 CLEARANCE FROM GROUND, BUILDING, TREES ETC.Clearance from ground, buildings, trees and telephone lines shall beprovided in conformity with the Indian Electricity Rules, 1956 asamended upto date.

2.7.1 The tree-cutting shall be the responsibility of the owner including forthat required during survey If any tree cutting by the contractor is

in square meters, clearly indicating the growth intree/bush statement.


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2.7.3 The contractor shall be responsible for tree enumeration for the

purpose of initiating proposal for obtaining forest clearance fromMinistry of Environment & Forest. The contractor shall submit 10copies of the complete proposal to be moved for forest clearance tothe satisfaction of the engineer-in-charge of the work.

2.8 PRELIMINARY SCHEDULE The profile sheets, duly spotted, alongwith preliminary schedulesindicating type of towers, type of foundations, wind span, weightspan, angle of deviation, river or road crossing and other detailsshall be submitted for the approval of the owner. After approval,the Contractor shall submit six more sets of the approved reportsalongwith one set of reproducible of final profile drawings to theowner for record purpose.

2.9 GEO-TECHNICAL INVESTIGATION:

2.9.1 The contractor shall be required to carry out the following field/laboratory tests or any other test which may be necessary forascertaining the soil properties required for design of thefoundations:

Sl Type of test Depth below NGL

edition of following IS codes and soil conditions available at site shall becarried out:


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IS: 1080 Code of practice for design and

construction of simple spreadfoundations.

IS: 1498 Classification and Identification of Soil forgeneral Engineering Purpose.

IS: 1892 Code of practice for SubsurfaceInvestigation for Foundation.

IS: 1904 Code of practice for design andconstruction of foundation in Soils:

General Requirements.

IS: 2131 Method of Standard Penetration Test forSoils.

IS 2720(Part 1) Methods of test for soils: Part 1Preparation of dry soil samples forvarious tests

IS 2720(Part 2) Methods of test for soils: Part 2Determination of water content

IS 2720(Part 3/Sec-1) Methods of test for soils: Part 3Determination of specific gravity, Fine

d l

content relation by constant mass of soilmethod

IS 2720(Part 10) Methods of test for soils: Part 10


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IS 2720(Part 10) Methods of test for soils: Part 10Determination of unconfined compressivestrength

IS 2720(Part 11) Methods of test for soils: Part 11Determination of the shear strengthparameters of a specimen tested inunconsolidated undrained triaxialcompression without the measurement of pore water pressure

IS 2720(Part 12) Methods of test for soils: Part 12Determination of shear strengthparameters of soil from consolidatedundrained triaxial compression test withmeasurement of pore water pressure

IS 2720(Part 13) Methods of test for soils: Part 13 Directshear test

IS 2720(Part 14) Methods of test for soils: Part 14Determination of density index (relativedensity) of cohesion less soils

IS 2720(Part 15) Methods of test for soils: Part 15Determination of consolidation properties

IS 2720(Part 24) Methods of test for soils: Part 24Determination of cation exchangecapacity


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IS 2720(Part 25) Methods of test for soils: Part 25Determination of silica sesquioxide ratio

IS 2720(Part 26) Methods of test for soils: Part 26Determination of pH value

IS 2720(Part 27) Methods of test for soils: Part 27Determination of total soluble sulphates

IS 2720(Part 28) Methods of test for soils: Part 28

Determination of dry density of soils, in-place, by the sand replacement method

IS 2720(Part 29) Methods of test for soils: Part 29Determination of dry density of soils in-place, by the core-cutter method

IS 2720(Part 30) Methods of test for soils: Part 30Laboratory vane shear test

IS 2720(Part 31) Methods of test for soils: Part 31 Fielddetermination of California bearing ratio

IS 2720(Part 33) Methods of test for soils: Part 33Determination of the density in place by the ring and water replacement method

IS 2720(Part 39/Sec2) Methods of test for soils: Part 39 Directshear test for soils containing gravelSection 2 In-situ shear test


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IS 2720(Part 40) Methods of test for soils: Part 40Determination of free swell index of soils

IS 2720(Part 41) Methods of test for soils: Part 41Measurement of swelling pressure of soils

IS 2809 Glossary of terms and symbols relating tosoil engineering May 2010

IS: 2911(Part 1/Sec2): Code of practice for design and

construction of Pile foundations: BoredCast in- situ concrete Piles.

IS: 2911 (Part 4): Code of practice for design andconstruction of Pile foundations: Loadtest on Piles.

IS: 6403 Code of practice for determination of Allowable Bearing Pressure on Shallowfoundation.

IS: 6935 Method of determination of Water level ina Bore-Hole.

IS: 8009 Code of practice for calculation of settlement of foundation subjected to

l l l d

2.9.4 The Geotechnical investigation report shall recommend the limitingbearing capacities at all the test locations for footing sizes 2.0m,2.5m, 3.0m, 3.5m and 4.0m at 3.0m depth below ground level.


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2.9.5 Strength parameters and consolidation parameters shall beevaluated by various field and laboratory tests e.g. tri-axial sheartest, direct shear test, Unconfined compression test, consolidationtest etc. depending on the available soil type.

2.9.6 The geo-technical investigation report shall include classification of soil, gradation, specific gravity, Atterberg limits e.g. Liquid limit,Plastic limit, plasticity index, in-situ density, bulk density, dry density, natural moisture content, void ratio and compression indexultimate & limiting bearing capacity of soil, strength parameters i.e.cohesion C and angle of internal frication , angle of response of soil etc.

2.9.7 The contractor shall submit the report of soil investigation of eachtower location in three copies to Purchaser for approval.

CHAPTER 3CHECK SURVEY, ERECTION, TESTING & COMMISSIONING


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3.1 SCOPE

3.1.1 This chapter covers check survey, erection, testing andcommissioning of the transmission lines enumerated in Section I -"GENERAL TECHNICAL REQUIREMENT". The successful bidderwill transport the tower members, tower accessories and otherline materials to the work sites.

3.1.2 The erection work shall also include the cost of labour, all toolsand plants including tension stringing equipment and all otherincidental expenses in connection with the check-survey, erection,testing & commissioning of the lines.

3.1.3 VARIATION IN QUANTITIES The rates indicated in the Price schedule shall hold good upto +

20% variation in quantity. When quantity against any itemexceeds 20% of the scheduled quantity the contractor shall bringthe fact to the notice of the Chief Engineer (Hydro), WAPCOS Ltd.well in advance and obtain his approval before commencingexecution of such excess quantity.

3 2 SPECIFIC TECHNICAL REQUIREMENTS

3.3 STANDARDS

3.3.1 Except where otherwise specified or implied the erection, testingd h ll f h f


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and commissioning shall conform to the provisions of IS :5613

(part 2 / Section-2) -1985 (as amended upto date).

3.3.2 The Indian Standard Specifications mentioned below shall beapplicable to the materials and processes used in executing thework.

i) IS: 383-1970 : Course and Fine Aggregatesfrom Natural Sources forConcrete.

ii) IS:1200-( Part I)-1974

: Method of Measurement of Building and Civil EngineeringWorks: Earthwork

iii) IS:456-1978 : Code of Practice for plain andReinforcement Concrete.

iv) IS:2502-1963 : Code of Practice for Bendingand Fixing of Bars forConcreteReinforcement.

v) IS:3043-1966 : Code of Practice for Earthing.


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reinforcement bars shall also be stored in separate piles in asuitable manner to minimise corrosion. Other line material shallbe stocked properly with a view of ease of handling, issue,

i i i i l h


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accounting minimum exposure to inclement weather etc.

3.7.3 The Erection Contractor shall store the aggregates on hardsmooth and clean surfaces so that there is no possibility of intrusion of any foreign materials. Aggregates of different gradesshall be stored in piles which shall be spaced well apart toprevent their intermixing.

3.7.4 Engineer-In-Charge shall have the right of excersising inspectionof Contractor's stores at any time to ensure no damages to thematerial.

3.8 RIGHT-OF -WAY, CUTTING OF TREES, ETC.

3.8.1 The purchaser will arrange the right of way along thetransmission line route. Any avoidable or deliberate damagedone to standing crop or private property by the Erection

Contractor's labourers shall be the Erection Contractor'sresponsibility.

3.8.2 The Purchaser will acquire only such piece of land as is actually required for each tower foundation. Any extra land required by the Erection Contractor temporarily for dumping of theconstruction material and consequent damage to crops etc shall

route shall be carried out with the types of structures and atangles as indicated in the approved profile sheets and towerschedules , ensuring that the minimum clearances at maximumt t i till i d diti ft t ki th ff t f


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temperature in still wind condition, after taking the effect of

conductor creep and slack caused by the broken conductor inthe adjoining span are not less than the relevant clearancesspecified in Section -II of this specification.

3.9.2 The crossings of railway tracks, telecommunication lines anderection of lines in the vicinity of aerodromes shall in additionmeet the requirements of the regulations/ code listed below:i) Regulation for Electrical crossing of Railway Tracks

issued by the Ministry of Railways.

ii) Code of Practice for Crossings between power andtelecommunication lines -1974 ( as amended upto date).

iii) Requirements for routing of over head lines in the vicinity of Aerodromes laid down by the Director, General of Civil

Aviation, Govt. of India.3.10 CROSSING OF PUBLIC UTILITIES

3.10.1 The Erection Contractor shall be responsible for giving requisitenotice to the appropriate authorities and intimate them the dateand time when he proposes to carry out erection of the

safety of the public. The time taken to effect the crossing shallbe kept to the minimum.

3 11 ERECTION TOOLS AND PLANTS


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3.11 ERECTION TOOLS AND PLANTS

3.11.1 The Erection Contractor shall provide at his own expenses allnecessary erection tools and plants such as surveyinginstruments, tackles, spanners, wrenches, pumps, timbering,scaffoldings, jacks, winches, ropes and all constructionmachinery such as tractors, bull dozers, hydraulic compressorsand dies, dynamometers, come along clamps, tension stringingequipments, camping requisites etc.

3.12 EXECUTION OF WORKS

3.12.1 Setting out and Check Survey

3.12.1.1 The duly approved profile sheets and tower schedules preparedon the basis of detailed survey shall be handed over to the

Contractor for carrying out the check survey. A preliminary tower schedule based on the check survey will be submitted by the Contractor. The locations of towers so marked shall be gotinspected from the authorised representative of the Purchaser.

The changes desired by the Purchaser in the preliminary towerschedule shall be carried out by the Contractor who shallthereafter submit a final tower schedule for the approval of the

3.14. CONSTRUCTION OF TOWER FOUNDATIONS :3.14.1 GENERAL

3 14 1 1 The type of foundation to be constructed at each tower location


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3.14.1.1 The type of foundation to be constructed at each tower location

shall be based on the soil characteristics indicated on the routeprofile sheets and as determined by the Purchaser during theprogress of the work. The Purchaser reserves the right to changethe type of foundation at any location where conditions duringthe progress of work indicated the use of a different type of foundation.

3.14.1.2 Each tower shall have four identical footings each of which shallhave steel stub angle embedded in concrete. The footings foreach tower in a straight section of the line shall be placed so thatthe longitudinal axis of the tower cross arm will be in a planeperpendicular to the transverse of the line. Unless otherwisedirected by the Purchaser, the footings for each angle tower shallbe placed in a manner so that the tower cross arms lie in a planebisecting the interior angle formed by the intersection of thetransverses of adjacent sections of the line.

3.14.1.3 Foundations shall be constructed in accordance with theapproved foundation drawings

3.15 SETTING OF STUBS :

filling. The sub-surface data regarding nature of soil, sub-soilwater etc. shown on drawings or otherwise furnished to thecontractor shall be taken as a guidance only, and any variationthere from shall not affect the terms of the contract The


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there from shall not affect the terms of the contract. The

Contractor must satisfy himself of the character and volume of all works under this item and expected surface, sub-surface, and/or subsoil to be encountered. He must also satisfy himself about general conditions of transmission line route and ascertainthe existing and future obstructions likely to come up during theexecution of the contract to carry out the work under this scope.

3.16.2 For purposes of excavation of earthwork, the term 'soil ' shallapply to all kinds of soil containing any percentage of kankar,moorum or/and shingle etc.

3.16.3 Excavations shall include the removal of all materials required toexecute the work properly and shall be made with sufficientclearance to permit the placing, inspection, setting of forms andcompletion of all works for which the excavation was made.

3.16.4 Sides and bottom of excavation shall be cut sharp and true tothe slopes indicated in the drawing. Undercutting shall not bepermitted. Earth sides of excavation shall not be used in lieu of formwork for placement of concrete unless authorized, inspecial cases, by the Purchaser or his representative wherelimitations of space for large excavation necessitate such a

3.16.9 Excavation shall not be carried below the foundation level of structures close by, until required precautions have been taken.

3 16 10 The contractor shall be responsible for assumptions and


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3.16.10 The contractor shall be responsible for assumptions and

conclusions regarding the nature of materials to be excavatedand the difficulty of making and maintaining the requiredexcavations and performing the work required as shown on thedrawings and in accordance with these specifications.Cofferdams, sheeting, shoring, bracing, and draining,dewatering etc. shall be furnished and installed as required.

The contractor shall be held responsible for any damage to any part of the work and property caused by collapse of sides of excavation. Material may be salvaged if it can be done withsafety for the work and structures, as approved by thePurchaser and no extra claim shall be entertained for materialsnot salvaged or any other damage to contractor's property as aresult of the collapse. He shall not be entitled to any claim forredoing the excavation as a result of the same.

3.16.11 Excavations for foundations where specified shall be carried atleast 100 mm below the bottom of structural concrete and thenbe brought to the required level of placing lean concrete of M-10(1: 3: 6) mix with coarse aggregate of 40 mm maximum nominalsize.

3 16 12 The contractor shall control the grading in the vicinity of all


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lines and grades as approved by the Purchaser. Payment forsuch excavation, including the associated grading shall bemade at the unit rate per cubic meter quoted in the Schedule of prices


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prices.

3.18. EXCAVATION FOR TOWER'S FOUNDATIONS:

3.18.1 SCOPE

This item covers excavation for the individual tower footings etc. The excavation shall be carried out as per clause 3.16.0 aboveand as described herein.

3.18.2 Except as hereinafter provided, all excavations for footings shallbe made to the lines and grades of the foundation designsapproved by the Purchaser. Any excavation done beyond thelines of the foundation shall be at the expense of theContractor. Any sand, mud, salt or other undesirable materialswhich may have accumulated in the excavated pits shall beremoved by the Contractor at no extra cost to the Purchaser,before placing the concrete. The rate of excavation shallinclude all associated activities like shoring, strutting,dewatering, stocking piling, dressing, back filling the foundationafter concreting with excavated / borrowed earth (irrespective of lead) and consolidation of earth, carriage of surplus earth to thesuitable point of disposal as required by the Purchaser or any

volume of excavation. The decision of the Purchaser shall befinal and binding with reference to the classification of soils.

3 18 5 The cost of drilling blasting & chiseling shall be included in the


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3.18.5 The cost of drilling, blasting & chiseling shall be included in the

quoted rates for hard rock excavation. Blasting materials shallbe arranged by the contractor at his own cost. For soils otherthan hard rock excavation rate to be quoted shall include thecost of back filling with excavated soil/borrowed soil.

3.18.6 Where rock is encountered, the holes for tower footings shallpreferably be drilled, but where blasting is to be resorted to asan economy measure, it shall be done in accordance with therelevant Indian Standard and with utmost care to minimize theuse of concrete for filling up the blasted areas. All necessary precautions for handling and use of the blasting material shallbe taken as per the requirements of the relevant Safety Codes.Only the persons having certificate for blasting issued by thecompetent authority shall be deployed for carrying out theblasting.In case, unnecessary large quantities are excavated / blastedresulting in the use of large volumes of concrete, payment forconcrete shall be limited to the guaranteed volume and the costof any concrete in excess of that shall be borne by theContractor. In case drilling is done, the stubs may beshortened suitably as approved by the Purchaser.

a) Where additional excavation is called for on account of alteration in the dimensions of excavation for a footing as aresult of the use of improper methods of excavation or


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result of the use of improper methods of excavation or

means for supporting excavation or providing inadequateprotection to the excavation against weathering or delay between excavating the pit and placing of the concrete by the Contractor, the cost of all additional excavation andalso that of all additional reinforcement, cement, concrete,backfilling and compacting shall be borne by theContractor.

b) Where additional excavation is called for due to change of the type of footing on account of different soil conditions,payment shall be made in accordance with the provisionexisting in this Specification.

3.19 EXCAVATION OF BORROWED EARTH FOR BACKFILL:

3.19.1 SCOPE: This item covers excavation of borrowed earth required forbackfill at the borrow areas designated by the Purchaser.

3.19.2 The Contractor shall strip the borrow area of all unsuitablematerial as may be necessary to obtain the required quantitiesof borrowed materials of approved quality The surfaces of

excavation cleaned of all trash, debris and perishable materials.Backfilling shall begin only with the approval of the Purchaser.

3 20 3 Back filling shall normally be done with the excavated soil


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3.20.3 Back filling shall normally be done with the excavated soil

unless it consists of large boulders/stones in which case theboulders shall be broken to a maximum size of 75 mm. Thebackfill material shall be clean and free from vegetation, piecesof timber and other undesirable materials. Back filling shall bedone with inorganic materials, obtained from the excavation orborrow pits and subject to the approval of the Purchaser.

3.20.4 Backfill shall not be dropped directly upon or against any foundation or facility where there is danger of displacement ordamage.

3.20.5 Backfill shall be placed in horizontal layers not to exceed 200mm in thickness. Each layer shall be compacted with propermoisture content with such equipment as may be required toobtain a density not less than 95% of maximum proctor dry density as determined by the relevant Indian Standards (latestedition). Trucks or heavy equipment for depositing orcompacting backfill shall not be used within 1.5 m of foundation that may damage the foundation by their weight oroperation. The methods of compaction shall be subject to theapproval of the Purchaser. Pushing of earth for backfilling shallnot be adopted under any circumstances

drawings or as directed by the Purchaser. Finished surfaceshall be free of irregularities and depressions and shall bewithin 50 mm of the specified level.


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3.20.11 MEASUREMENT:

The cost of backfilling and compaction is deemed to be includedin the unit prices quoted for excavation in clause 3.18.7.

3.21 FORM WORK:

3.21.1 SCOPE:

This section covers technical requirements for furnishing andinstallation of formwork for construction of tower foundations.

The contractor shall furnish all labour, equipment andmaterials required for complete performance of the work inaccordance with the drawings and as described herein.

Formwork shall be as per IS: 456-2000 and shall be composedof steel and /or best quality shuttering wood of non-absorbenttype timber. The timber shall be free from knots and shall be of medium grain as far as possible.

3.21.2 The formwork shall conform to the shape, lines and dimensionsof the footings as per the approved foundation drawings All

3.21.4 MEASUREMENT

The cost of formwork is deemed to be included in the unitprices quoted for concreting.


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prices quoted for concreting.

3.22 CONCRETE

3.22.1 SCOPE

This section covers the technical requirements in respect of materials used in forming, mixing, placing, finishing, curingand testing of plain and reinforced cement concrete forfoundation for transmission line towers. The contractor shallfurnish all materials, labour, equipments etc. required forcomplete performance of the work in accordance with thedrawings and as described herein.

3.22.2 STANDARDS

a) Except where otherwise specified or implied, the concreteshall conform to the provisions of IS:456 - 2000.

b) The Indian Standard Specifications mentioned below shallbe applicable to the materials and processes used in thepreparation of concrete.


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c) FINE AGGREGATES

Coarse and fine sand shall be well graded within the limitsby weight as specified in IS: 383(Latest). Fineness modules


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y g p ( )

shall not vary by more than plus or minus 0.20 from that of the approved sample. Fineness modules for sand shall notbe less than 2.5. Washing of fine aggregates by approvedmeans shall be carried out, if found necessary by Purchaser. Coarse and fine aggregates shall be batchedseparately.

Fine aggregates shall be so stored so as not to get mixedwith soils or other deleterious materials. The fine aggregateshall be stored on hard firm ground having sufficient slopeto provide adequate drainage for rainwater. The stack of the fine aggregates shall be such that the same may bemeasured easily whenever found necessary by the owner orhis authorized representative.

d) WATER

Water used for mixing and curing the concrete shall beclean, fresh and free from injurious amounts of oil, acids,alkalies, organic material or other deleterious matters insolution or in suspension in such amounts that may impairthe strength or durability of the concrete Saltish and


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aggregates and cement expected to be used on the job toascertain the ratios by weight of cement to totalquantities of fine and coarse aggregate and the watercement ratio required to produce a concrete of specified


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q p p

strength and desired workability.

c) Mix design for all grades of design mix concrete shall beundertaken to investigate the grading of aggregates,water cement ratio, workability and the quantity of cement required to give concrete the minimum strengthspecified in IS: 456 and these specifications whichever ismore. The proportions at the mix shall be determined by

weight. Adjustment of aggregate proportions due tomoisture present in the aggregate shall be made.

-----------------------------------------------------------------------------------------------Grade of Concrete M-15 M-20 M-25

--------------------------------------------------------------------------------------------------- -----(i) Preliminary Tests at 28 days 20N/mm 2 26N/mm 2 31N/ mm 2

(ii) Work tests at 7 days 10N/mm 2 13.5N/mm 2 17N/ mm 2(iii) Work tests at 28 days 15N/mm 2 20N/mm 2 25N/ mm 2

---------------------------------------------------------------------------------------------

Note:(i) P li i T t A t t d t d i l b t th t i l i

3.22.9 CONCRETE MIX REQUIREMENTS

a) Design mix concrete as defined in IS: 456 shall be used forall foundations unless permitted otherwise.


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b) Concrete mix shall conform to IS: 456 and thesespecification.

c) MINIMUM CEMENT CONTENT IN CONCRETE

The minimum quantity of cement content for each grade of concrete notwithstanding the strength requirements

specified in the specification, shall not be less thanspecified in Table-5 of IS:456-2000 depending on exposureor as given below whichever is more.

Grade Of Concrete

Minimum Cement Content Per CubicMeter

M-10 240 KgM-15 280 KgM-20 320 KgM-25 350 Kg

d) Based on the contractor's mix design, if the actualrequirement of cement for a grade of concrete is found tobe more than those specified above such excess quantity of

Complete certified reports prepared by an independenttesting laboratory and covering the materials andproportions shall be submitted to the Purchaser. Review of these reports shall be for generally acceptability only and


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continued compliance with all contract provisions only shallbe required. The Purchaser shall have the option to witnessthe preparation of the trial mixes, testing etc.

b) Reports on admixture shall include the classification, brand,manufacturer and active chemical ingredient. Alladmixtures, conforming to relevant IS Codes, shall be theproducts of one manufacturer approved by the Purchaser.

c) Reports on the coarse aggregates shall include the source,type, gradation, deleterious substances, soundness,abrasion loss and the results of all tests required to comply with IS: 383 (Latest edition).

d) Reports on the fine aggregates shall include the sources,type, gradation, deleterious substance, soundness and theresults of all tests required to verify compliance with IS: 383(Latest edition).

e) Using concrete materials acceptable to the Purchaser, atentative concrete mix shall be designed and tested for eachsize and gradation of aggregates and for each consistency

test.

9. Time of initial set.

10. Weight of cement used in the mix.


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g) Concrete tests specimens shall be made, cured and tests inconformity with IS: 516 (Latest edition). These tests shall beconducted at approved laboratory. The mould and materialsfor cubes shall be supplied by the contractor who shall alsoarrange to transport the cubes to laboratory at his cost.Actual cost of the testing shall also be borne by theContractor.

3.22.11 CONCRETE MIXING

a) Concrete mixing shall conform to IS: 456-2000. Concreteshall normally be mixed in a mechanical mixer. Mixing onmetallic watertight platform shall be allowed only in very difficult approach area with 10 % additional cement at noextra cost to Purchaser.

b) The proportion of fine and coarse aggregates, cement andwater shall be as determined by the mix design in case of controlled concrete. The quantities of fine and coarseaggregates shall be determined by weight. The Purchasermay allow the quantity of aggregates to be determined by

additional 0.75 cu.m or fraction thereof. All concrete shall bedischarged within 3 minutes after the introduction of mixingwater to the cement and aggregates, unless a different timeis specified by the Purchaser.


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d) Before beginning a run of concrete, all partially set orhardened concrete and foreign material shall be removedfrom the inner surfaces of mixing conveying equipment. Thefirst batch of concrete for use in the works, through acleaned mixer and shall contain 10% additional cement atno extra cost to allow for loss in the drum. All conveyances,buggies and barrows shall be thoroughly cleaned at frequent

intervals during the placing of concrete. Concrete shall berapidly handled from the mixer to the place of final depositand shall not be delivered by spout or troughs nor dumpedinto carriers with a free fall from the mixer of more than 1.0M. Every possible precaution shall be taken to preventsegregation or loss of the ingredients while transporting theconcrete.

3.22.12 CONCRETE PLACEMENT

(a) The handling, depositing and compacting of concreteshall conform to these specifications, subject toadjustments by the Purchaser for weather or placementconditions During hot or cold weather the concreting

position without moving it laterally in the forms for adistance in excess of 1.5 meter.

(e) Concrete shall be deposited in approximately horizontal


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layers to proper depth for affecting compaction. However,the depth of a layer shall not exceed 300 mm. Each layerof concrete shall be plastic when covered with thefollowing layer and the forms shall be filled at a rate of vertical rise of not less than 150 mm per hour.Construction joints shall be provided as necessary and asaccepted by the Purchaser to comply with theserequirements.

(f) Plastic concrete is defined as concrete which can be re-vibrated at least to the extent that an immersion typevibrator stud shall penetrate into the concrete at least 25mm by vibration action and its weight. Concrete which isnot longer plastic but which must be covered by anadditional lift shall be immediately chipped back to wellconsolidated concrete and flushed with mortar puddle asfollows:

The surface of hardened concrete upon which freshconcrete is to be placed shall be rough and clean anddamp. Surface mortar shall be removed to expose theaggregate The hardened surface shall be cleaned of all

deposit as rapidly as practicable by methods, which shallprevent segregation.

(i) Concrete shall normally be placed in continuous


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horizontal layers. Construction joints in foundationsshall not be permitted. Concrete shall be compacted tothe maximum practicable density during the placementand thoroughly worked around the reinforcement, if any,and around the embedded stubs and into the corners of the formwork, with vibrators or any other meansapproved by the Purchaser.

(j) Repairs of imperfection in concrete shall be completedwithin 24 hours after the removal of forms. Repair of concrete shall be performed only in the presence of thePurchaser or his authorized representative. All exposedcorners shall be slightly rounded or chamfered. Concretein the top of footings shall be sloped to provide drainageaway from stub angles.

3.22.13 TEMPERATURE OF CONCRETE

i) In hot weather, the temperature of concrete when it isplaced in the forms shall not be more than 38 deg C. Inextreme hot weather, some suitable means out of thosementioned below shall be employed to lower the

iii) If subject to the approval of Purchaser, heating of aggregateis used, the aggregate shall be heated uniformly andcarefully avoiding overheating and excessive drying. The


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average temperature of aggregate shall not exceed 65 deg Cand the maximum temperature shall not exceed 100 deg C.

3.22.14 STRIPPING TIME

Under fair weather conditions with average daily temperaturenot less than 20 deg C and when ordinary cement is used,forms may be struck after 24 hours of placing the concrete. In

very cold temperatures, the forms shall be struck after 48 hoursof the placing of concrete.

3.22.15 PROTECTION OF CONCRETE

a) In very cold weather, the concrete shall be protected fromfreezing for at least 48 hours of placement when the meandaily temperature is 4.5 deg C. When the mean daily temperature in the vicinity of work site falls below 4.5 deg Cfor more than one day, the concrete shall be maintained ata temperature not less than 10 deg. C for at least 72 hoursafter it is placed. Concrete cured by water curing shall beprotected at 10 deg C

retention of the original heat of concrete plus heat of hydration. Curing shall be carried out for longer periods tothe satisfaction of Purchaser, to ensure that the concreteattains the strength and quality.


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3.22.17 SAMPLING AND TESTING

a) Samples shall be cured under laboratory conditions exceptwhen in the opinion of the Purchaser, the extreme weatherconditions may prevail at which time the Purchaser may require additional cubes cured under job conditions.

b) The Contractor shall promptly furnish to the Purchasercertified reports of all tests made by the testing laboratory.

c) If the strength of the cubes for any portion of the concretework falls below the specified compressive strength, thecriteria for acceptance of the portion of the work shall be asstipulated in IS: 456-2000. The Purchaser shall alsoreserve the right to reject whole or any part of the work. Incase of acceptance of such works, the standard deviationsshall be worked out, and examined by the Purchaser and if he is satisfied only then such works can be accepted at thereduced rates provided with reduced strength of concrete,the design of foundation is found to be safe. Furthermore,the Purchaser shall have the right to order a change in the

3.23 REINFORCEMENT

3.23.1 SCOPE:


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This section covers the technical requirements for supply andinstallation of reinforcement steel in foundation work of transmission line towers. The contractor shall furnish allmaterials, labour and equipment required for completeperformance of the work in accordance with the approvedfoundation drawings and as described herein.

3.23.2 Reinforcing steel shall be clean and free from loose mill scales,

dust, loose rust and coats of paints, oil, grease or othercoatings, which may impair or reduce bond. It shall conform tothe following IS Specifications:

High Yield Strength Deformed reinforcement steel of grade Fe-415 or Fe-500 conforming to of IS: 1139 and IS: 1786 shall beused. All steel reinforcements including and above 6mmdiameter shall necessarily be of tested quality.

3.23.3 Reinforcement accessories shall be furnished by the contractor.Binding wire shall be annealed iron wire quality not less thanNo. 16 swg (1.65mm dia.). Bar support, chairs and bolstersshall be sufficiently strong to support the steel reinforcementproperly

packed with boulders. The top seal cover of the revetment workshall be done with M-15 grade concrete. The Contractor shallfurnish recommendations for providing protection at suchlocations. Where the ground surface is irregular, the

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