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NAME OF THE PROJECT–
DESIGN & CONSTRUTION OF ELEVATED STRUCTURES (VIADUCT) EXCLUDING STATION PORTIONS IN REACH 4 BETWEENSHIVASHANKARA CIRCLE ON K.R. ROAD TO R.V.ROAD.
CLIENT–
BANAGLORE METRO RAIL CORPORATION LTD.
EPC CONTACTOR –
NAGARJUNA CONSTRUCTION CO.LTD.
CONSULTANT–
RITES – OCCL – OC – SYSTRA
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CERTIFICATEThis is to certify that the project entitled
“BANGALORE METRO RAIL PROJECT-REACH 4”has been successfully carried out at our NCC
site, byRAHUL CHAUHAN, student of final year B.E. in
Civil Engineering fromSIR M VISVEVARYA INSTITUTE OF TECHNOLOGYhas submitted this report under our guidance,
during the academic year 2010-2011.
Mr. R. G. SHANBHAG (Sr. Manager)
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CONTENTS
General Profile
Introduction of Elevated Structures
Construction of Pile Work
Construction of Pile Cap
Construction of Pier and Pier Cap
Casting of Precast Segments
Erection of Segments
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GENERAL PROFILE
The work consists of design & construction of Elevated Structures (viaduct) excluding station portions in reach 4 between shivashankaracircle on K.R.Road to R.V.Road end. The whole contract consists of construction of 142 Piers from P-1 to P-141 on the proposed site. The construction detail of piers is explained. The general route of this contract is shown in diagram below: -
INTRODUCTION OF ELEVATED STRUCTURES
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The construction of such elevated structures is divided into 5 categories which are mentioned below: -
1. Construction of Piling
2. Construction of Pile Cap
3. Construction of Pier and Pile Cap
4. Casting of Precast Segment
5. Erection of Segment
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CONSTRUCTION OF REGULAR PILING WORK
PURPOSEThe purpose of this procedure is to follow uniform work methodology and to perform various activities in sequence for construction of regular piling works.
DETAILS OF PILES Total length – 10m-30mTotal no. of spans - 142 nos.No. of bored cast-in-situ pile - as per designMax. Length of pile – 30mDiameter of pile - Min. spacing between piles (c/c) - Max. Spacing between piles (c/c) -Min. spacing pile group (c/c) - Max. Spacing pile group (c/c) -Open foundations envisage between pile group – yesPermanent casing of pile – as per site conditionNo. of Pile in group – as per design
CONSTRUCTION MATERIAL DETAILS
(a). Concrete –S no. Material Specification
1 Cement IS 4552 Aggregates IS 3833 Water C 15.4 of IS
4564 Admixtures IS 9103
(b). Reinforcement steel –S no. Material Specification1 All dimensions of reinforcement
steelIS 1786
(c). Structural steel –S no. Material Specification1 All dimensions of plates IS 2062
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Other construction material shall be procured on later stages as & when need arises.
CONSTRUCTION ACTIVITIES
(a) Layout of Structure: Construction of piling shall start after carrying out survey for alignment &level in accordance with approved drawings. Grid pillars shall be constructed at regular intervals and reference for construction shall be taken from these grid pillars. The same shall be duly checked and reviewed by clients. Then each pile location shall be marked at ground before starting the piling work for the location.
STEP-1BORED PILING
(b) Aligning the Piling Rig: Piling rig shall be mobilized to the positioned by keeping Kelly bar true to vertical at the piling location.
STEP 2
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1. Set out the positions of bored piles as per construction drawing.
2. Mark the pile position with pegs.
3. Survey the existing ground level at the pile positions.
4. Inform the existing ground level to the section in charge.
1. Mobilize the boring plant to the intended bored pile position.
2. Position the centre of auger/bucket exactly above the pile point.
3. Check the vertically of Kelly bar before boring commences.
4. Offset two reference points perpendicular to each other from the pile position.
(c)Boring of Pile in Soft Strata: After aligning the boring rig in position boring in top soil shall be commenced with soil barrel buckets/ soil augers upto the non-collapsible length. During boring the verticality of the drilled hole shall be constantly checked. And also the position of the bore shall be cross checked with the reference points.
STEP 3BORED PILING
(d) Installation of Temporary Casing: while boring through the soft strata the stability of boring is most important to arrest any collapse of the soil in to the bore and making the shaft into the constant diameter.MS liner/casing shall be installed up to the bottom of the soft strata with the help of service crane or secondary winch from the boring rig.
STEP-4
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1. Commence boring at the pile position.
2. Check the verticality of drilled hole during boring works.
3. Cross check the position of bore hole before advancing the boring works.
4. Observe the stability of bore hole.
5. Collect the soil sample to verify the soil strata.
6. Observe any ground water table is available.
1. Observe the stability of bore hole during boring work.
2. If the bore hole is unstable insert a temporary casing into the bore hole.
3. Check the verticality of temporary casing during installation. Use 2 plumbs in positioned in perpendicular direction to each other.
(e) Boring of Pile in soft strata or hard strata after installation of guide casing : after installation boring into the soft strata shall be advanced further with soil barrel bucket or soil auger till the design depth or up to the hard soil. If the boring is to be done in weak strata, bentonite may be usedafter due consultation with engineers to avoid collapse of bore side. The properties of bentonite should be as per the technical specification.
(f) If hard material is encountered during boring use chisels or rock tools to penetrate into the hard stratum.
STEP-5
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(g) Termination of bore hole: after reaching the borehole up to designed depth the same shall be offered to clients/contractor for inspection & review. The comments and suggestion of clients/contractor shall be attended promptly.
(h) Cleaning of borehole: after attending the comments & suggestions given by clients/contractor. After the inspection, cleaning of the base of bore hole shall be carried out with a cleaning bucket.
STEP 6
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1. Continue boring with an auger or boring bucket depending on soil condition as shown in fig. (a) & (b).
2. Continue to check the verticality of Kelley bar till the completion of bore hole.
3. Carry out boring till the designed depth is achieved or hard stratum encountered.
4. If the hard material is encountered during boring, use chisel or rock tools to penetrate into the hard stratum as shown in fig.
5. Carry out boring till designed depth is achieved.
(i) Placing & lowering of reinforcement cage: specially fabricated reinforcement cage brought to the site shall be checked for intact & dimensions, cover blocks, etc., and are appropriate to the intended pile. Sufficient preventive care shall be taken for the handling disturbances. Then the cage shall be hoisted with the service crane/rig winch and gently lowered to the bore hole. The cage shall be anchored to the guide casing with the help of rebar. If any additional length is to be added to form the required length. Then second cage shall be hoisted with the help of service crane/rig winch and brought to the location and positioned on top the anchored cage. Then two cages shall be welded/coupled together firmly and the full cage shall be hoisted to the service crane. Anchoring arrangements shall be removed and the full cage shall be lowered up to the pile base.
STEP-7
(j) Lowering of Tremie pipe: After placing the reinforcement cage tremie of appropriate dia. i.e.200/250mm tremie pipe with hopper shall be lowered in to the bore hole. Before lowering the pipe it will be ensured that the joints are water tight and intact. The gap between the base of pile and bottom of the tremie shall be kept 150mm if the bore hole is wet and if it is dry bore the gap between base of pile and
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1. After reaching the design depth, clean the base of borehole with a cleaning bucket.
2. Verify and confirm the pile length with engineer’s representative.
4. Hoist the reinforcement cage to the service crane.
6. Verify lower the reinforcement cage into the bore hole to the base of bore hole or to cut-off-level.
7. Ensure that the cage is maintained at the cut off level during concreting works.
1. Check & ensure the reinforcement and dimensions of cage are appropriate for the intended pile.
2. Ensure that the cage is intact for handling.
3. Ensure the cover blocks are in position.
tremie shall be maintained less than 1.5m. A plug is also placed on the hopper for the first charge.
(k) Concreting of borehole:1. Concreting in dry hole condition : An indent for the concrete will be sent to the
centralized batching plant in charge after approval of the borehole for concreting. Concrete produced as per the approved design mix in centralized batching plant at casing yard shall be brought to the site through transit mixers along with the docket specifying the mix details, qty of concrete, bathing time, initial slum, temperature, etc. After receiving the docket the concrete shall be sampled for the slum, temperature and cube casting. After the site QC engineer certifies the concrete, the concrete shall be discharged directly in to the hopper of the tremie. When concrete has reached above cut-off-level stop the concrete works. It shall be ensured the sound concrete has reached the cut-off-level.
STEP -8
2. Concreting in wet hole condition : An indent for the concrete will be sent to the centralized batching plant in charge after approval of the borehole forconcreting. Concrete produced as per the approved design mix in centralized batching plant at casting yard shall be brought to the site through transit mixers along with the docket specifying the mix details, qty of concrete, bathing time, initial slum, temperature, etc. After receiving the docket, the concrete shall be sampled for the slum, temperature and cube casting. After the site QC engineer certifies the concrete, the concrete, the concrete shall be discharged directly in to the hopper of the termie. It shall be ensured that the gap between base of the pile and bottom of the termie shall be of 150mm. The plug shall be placed in the tremie before charging the tremie with concrete. After filling the tremie with concrete then plug shall be removed with help of service crane. Then after concrete shall
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1. Discharge concrete directly from the transit mixer in to the hopper.
2. When concrete has reached above the cut-off-level, stop concreting works.
3. Ensure that sound concrete has reached above the cut-off-levels.
be poured in to tremie continuously. It shall be ensured that the end of tremie shall be in concrete minimum of 3m. Draw tremie pipe as concrete rises upwards. When concrete has reached above cut-off-level, stop the concrete works. It shall be ensured the sound concrete has reached above the cut-off-level. Extract the guide/temporary casing from the bore hole upon completion of concreting works. It shall be ensured that the guide casing shall be extracted vertically and no disturbance to the concrete and mixing of soil with the concrete.
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1. Insert the concrete plug at the top of the tremie pipe hole.
2. Lower the tremie pipe to the toe of the borehole.
3. Discharge concrete directly from the transit mixer in to the hopper and fill it.
4. Remove tremie plug with the help of service crane.
5. Fill concrete from the bottom of bore hole which displays the sludge as concrete rises to the top.
6. Withdraw the tremie pipe as concrete rises upwards.
7. Always maintain minimum 3 m length of tremie is embedded in to the concrete during concreting works.
8. When concrete has reached above the cut-off- level withdraw tremie pipe.
9. Ensure that the sound concrete has reached above the cut-off-level.
TESTING & RECORD
The following routine test shall be carried out on the fresh concrete during concrete work and to be carried out prior to placing of concrete.Slump/workability test shall be carried out at the pouring location.Records shall be kept for all batches of concrete and sampling of concrete shall be done. The pour card/slump test report and recording of following shall be done:—location/volume of concrete.—grade of concrete.—concrete mix used.—slump of concrete.—sampling of concrete for test cube.
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1. Insert the concrete plug at the top of the tremie pipe hole.
2. Lower the tremie pipe to the toe of the borehole.
3. Discharge concrete directly from the transit mixer in to the hopper and fill it.
4. Remove tremie plug with the help of service crane.
5. Fill concrete from the bottom of bore hole which displays the sludge as concrete rises to the top.
6. Withdraw the tremie pipe as concrete rises upwards.
7. Always maintain minimum 3 m length of tremie is embedded in to the concrete during concreting works.
8. When concrete has reached above the cut-off- level withdraw tremie pipe.
9. Ensure that the sound concrete has reached above the cut-off-level.
1. Extract guide/temp casing from the borehole upon completion of concreting works.
2. Ensure that the temp casing is extracted vertically.
Concrete cube shall be cast for compressive strength tests. Frequency of testing shall be as per IS 456-2000.
Quantity of Concrete in m³ No. of samples0-5 16-15 216-30 331-50 451 & above 4 plus on additional sample for each 50m³
or part there ofHalf the total cubes cast shall be crushed for 7 days compressive strength and the remaining half shall be crushed for 28 days compressive strength. Additional cubes shall be taken for testing on 1 day &3 days for the shuttering and lifting etc.
EQUIPMENTS TO BE USED
Following is the list of various equipments to be used for Pile concrete:-
Sl.no. Equipment description Unit Quantity1 Batching plant -60-30 m³/hr or more capacity Nos. 12 Trailor NO 13 Transit mixer-6m³ capacity Nos. 1 to 3 nos.4 Hydraulic piling rig Nos. 15 Tremie pipe with hopper set Nos. 16 Service crane Nos. 17 Guide casing Nos. 18 Boring tools Set 19 Survey equipment Set 1
10 Cube moulds Nos. As required11 Slump cone Nos. 1
CONSTRUCTION OF PILE CAP
PURPOSE
The purpose of this procedure is to follow uniform work methodology and to perform various activities in sequence for construction of pile caps.
CONSTRUCTION MATERIAL DETAILS
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(a). Concrete –Sl.no.
Material Specification
1 Cement IS 4552 Aggregates IS 3833 Water C 15.4 of IS 4564 Admixtures IS 9103
(b). Reinforcement steel –Sl.no Material Specification1 All dimensions of reinforcement steel
TMT Fe500IS 1786 Gr Fe500
CONSTRUCTION ACTIVITIES
(a) Layout of structure: all structures shall after carrying out survey for alignment and levels in accordance with approved drawings. Grid pillars shall be constructed at regular intervals and reference for construction shall be taken from these grid pillars. The same shall be duly checked and approved by clients/contractor.
(b) Earth work in extraction for pile cap: layout of excavation area: the area to be excavated shall be clearly marked over the ground. This should be done using lime powder or similar means. Area to be excavated should be sufficient to allow for the working space. Initially the road portion shall be excavated with the help of pavement breaker attached to the compressor. Depending upon the site condition, either the mechanized or the manual excavation shall be done to reach the level as required by the drawings/specifications. If any utilities are encountered at the time of excavation, the same shall be informed to clients/contractor/the local authorities for removal/diversion. After reaching required level, approval from clients/contractor shall be taken for further activity.
(c) Chipping of excess Concrete of Piles: after excavation of the surface for pile cap up to the required level, the excess concrete at the top shall be removed up to the pile cut off level with the help of concrete breaker attached to compressor or with electro pneumatic breakers as per the site conditions. Then the pile surface
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will be cleaned and any loose concrete/disturbed concrete will be removed from the surface.
(d) Laying of PCC: The strata on which PCC shall be laid to be cleaned for any loose soil, debris etc. M15 PCC shall be laid as per approved mix design concrete shall be placed in position with the help of a chute. Concrete shall be levelled and compacted with the hand float of wooden/aluminium box section. Curing of concrete shall commence after 8-10 hours of placement. Curing shall be done by covering with wet hessian cloth or sprinkling water on concrete surface. The layout/centre line shall again be transferred over the PCC as reference for further construction activities. The rebar positions for the pile caps shall be marked in the layout and shall be checked by the site Engineers for the foundations.
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(e) Reinforcement: All the reinforcement used shall conform to IS 1786 grade TMT Fe500. The bars shall be placed/stacked on wooden sleepers/CC blocks. The bars shall be stacked in lots and diameter wise at yard. Cutting & bending of reinforcement will be done at yard and will be brought to site through trailers/trucks. Then the rebar will be placed on top of the already laid PCC with required cover blocks. And tying of reinforcement shall be as per approved BBS/drawings. Due care will be taken for maintaining the required cover to reinforcement. The cover blocks shall be PVC or of higher grade of concrete already cast and cured at laboratory.
(f) Embedded parts: All the embedded parts shall be fixed as per drawings.
(g) Formwork: The formwork shall have sufficient strength to withstand the weight and pressure of concrete and other constructional loads without deflection, distortion, bulging or loosening the supports.
(h) Concrete: The concrete grade of M35, as required for the pile caps foundation shall be produced after receiving indent from the section in charge. The concrete produced in batching plant at casting yard shall be transported to the site by means of transit mixers. All transit mixers shall be insulated properly and kept wet till completion of concrete for better retention.
(i) Concrete Placement: The Engineer’s representative at site shall inform to their Q.C representative at casting yard to start concrete production, after giving approval for concrete pour. Before commencement of concreting the pour area shall be made free from pieces of timber, rebar and other foreign material. If necessary the earlier concrete shall be conveyed to placement point through chute/crane bucket/concrete pump depending on the necessity and situation. Concrete shall be placed in layers of 450mm thick panels covering the entire plan area in to two/three panels. Then the successive layers shall be placed with in 6 hours from the production time of the previous layer. Due care shall be taken that the two layers shall be properly keyed when the concrete is in green condition.
(j) Concrete Compaction: Freshly laid concrete shall be duly vibrated in layers by mechanical vibrator, to ensure the full compaction of concrete and reach of
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concrete in all corners and pockets of pour. Around embedded parts, care shall be taken while vibrating the concrete. The concrete shall be vibrated to achieve maximum density. For this purpose immersion type high frequency vibrators shall be used and the vibrator needle shall always be inserted vertically. The vibrator needle shall be allowed to penetrate in the concrete by its own weight and external force shall not be applied. Insertion of the vibrator needle shall be done at an interval of 400-600mm. The best vibration time is 15-20sec. Over vibration shall be avoided. In case plastic shrinkage cracks are noticed during concrete in spite of all precautions being taken, the rectification work shall be followed.
(k) Curing of Concrete: After 8-10 hours of concrete pour, curing shall be started by covering with hessian cloth or sprinkling of water on it.
TESTING & RECORD
The following routine test shall be carried out on the fresh concrete during concrete work and to be carried out prior to placing of concrete.Slump/workability test shall be carried out at the pouring location.Records shall be kept for all batches of concrete and sampling of concrete shall be done. The pour card/slump test report and recording of following shall be done: —location/volume of concrete. —grade of concrete. —concrete mix used. —slump of concrete. —sampling of concrete for test cube.Concrete cube shall be cast for compressive strength tests. Frequency of testing shall be as per IS 456-2000.
Half the total cubes cast shall be crushed for 7 days compressive strength and the remaining half shall be crushed for 28 days compressive strength. Additional cubes shall be taken for testing on 1 day &3 days for the shuttering and lifting etc.
EQUIPMENTS TO BE USED
Following is the list of various equipments to be used for Pile concrete:-
Sl.no. Equipment description Unit Quantity1 Batching plant -60-30 m³/hr or more capacity Nos. 12 Transit mixer-6m³ capacity Nos. 33 Vibrator with 60mm needles Nos. 44 Concrete pump Nos. 1
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5 Crane with bucket Nos. If required6 Survey equipment Set 17 Cube moulds Nos. As required8 Slump cone Nos. 1
CONSTRUCTION OF PIER AND PIER CAP
PurposeThe purpose of this procedure is to follow uniform work methodology and to perform various activities in sequence of construction of Pier and Pier Cap.
Details of PIERTotal length – 3610m.Total no. of spans – 135 nos.No. of Piers – 142 nos.No. of abutments – 1 no.Minimum height of Pier – 1.5m.Maximum height of Pier – 13m.Minimum spacing of Pier – 22m.Maximum spacing of Pier – 31m.
Construction Materials Details(a). Concrete –S no.
Material Specification
1 Cement IS 122692 Aggregates IS 3833 Water IS 4564 Admixtures IS 9103
(b). Reinforcement Steel –S no. Material Specification1 All dimensions of reinforcement
steelIS 1786-Fe500
(c). Structural Steel –S no. Material Specification1 All dimensions of plates IS 2062
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Construction Activities
(a) Layout of Pier/Pier Starter: Construction of Pier and Pier Cap shall start after completing the construction of Pile Cap/Open foundation. The layout of Pier starter shall be marked on top of the Pile Cap for alignment and levels in accordance with the approved drawings.
(b) Pier Starter Construction: The formwork shall be placed in the position and properly supported. Any loose concrete on top of the Pile cap shall be removed and the surface shall be made wet. Approved bonding agent shall be applied as per the manufacturer instructions. 4 nos. of shear keys of size 200x150x150mm shall be provided. Concretes are used laid as per specified approved designed mix concrete shall be produced form 60 cu.mt. Per hour batching plant and shall be transported to location through transit mixture. Concrete shall be placed in position with the help of wheel barrow or with white ghamela. Concrete shall be levelled and compacted with internal needle vibrator of 40mm needle and hand float of wooden sections to get the required level as per the approved drawing. Curing of concrete shall commence immediately after 8-10 hours of placement. Curing shall be done as per CI.3.10.6 of TS. The layout/centre/outer line shall again be transferred over the pile cap/footing as a reference of further construction activities.
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Cross-section of Pile Cap/Open foundation(c) Placing, positioning and tying of rebar: False Work (supports) for fixing rebar shall
be erected in position along with templates for controlling the rebar position. The false work to be used shall be as per the approved design and drawing. Then the fabricated rebars shall be placed in position and tied with eachother to maintain its position. Then the cover blocks shall be fixed to the rebar to maintain the cover to the reinforcement. Utmost care shall be taken to support the reinforcement in vertical position to avoid any untoward accident.
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Placing, positioning and tying of rebar(d) Fixing of Drainage Pipes and other embedded parts: After completing the rebar
works for the Pier and Pier caps, PVC pipes as per IS 4985 for storm water down take other embedded parts shall be placed in its final position.
(e) Placing of Pier and Pier cap formwork: After fixing Drain pipe and other embedded parts, the Pier and Pier cap formwork shall be placed in position along with false work. Prior to the placing of the Pier formwork in position form surface shall be applied with approved form releasing agent. The entire assemble shall be positioned along with temporary works and inserts.
(f) Closing of Pier formwork: After placing into final position all the form members shall be closed with the screw jacks and then bolted.
(g) Verticality and Alignment Checking: The entire assembly shall be checked for its verticality by using plumb bob and the alignment shall be checked by surveyor using Total Station. The supports and the false work shall be locked after final alignment.
(h) Final Checking: The entire assembly shall be given for final checking to Client and permission shall be obtained for pouring of concrete.
(i) Concreting: The Engineer’s representative at the site shall inform to their Q.C. representative at casting yard to start concrete production, after giving approval for concrete pour. Before commencement of concreting the pour area shall be made free from pieces of timber, rebar and other foreign material. If necessary the earlier concrete shall be cleaned with air or water jet. The following procedure shall be followed for concreting :
1) Concrete placement.2) Concrete compaction.3) Curing of concrete.4) Removal of Shutters.5) Backfilling of the foundation.
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TESTING & RECORDThe following routine test shall be carried out on the fresh concrete during concrete work and to be carried out prior to placing of concrete.Slump/workability test shall be carried out at the pouring location.Records shall be kept for all batches of concrete and sampling of concrete shall be done. The pour card/slump test report and recording of following shall be done:—location/volume of concrete.—grade of concrete. —concrete mix used.—slump of concrete.—sampling of concrete for test cube.Concrete cube shall be cast for compressive strength tests. Frequency of testing shall be as per IS 456-2000.
EQUIPMENTS TO BE USE
Following is the list of various equipments to be used for Pile concrete:-
Sl.No. Equipment description Unit Quantity1 Batching plant -60 m³/hour Nos. 12 Cement Silos Nos. 23 Transit mixer-6m³ Capacity Nos. As required4 Vibrators with 60mm needles Nos. 45 Concrete Pump Nos. 16 Crane with Bucket Nos. 17 Survey Equipment Nos. 18 Cube Moulds Nos. As required9 Slump Cone Nos. 1
CASTING OF PRECAST SEGMENT
PURPOSE
It is propose to precast the segments on long line beds. Segments for straight and curved spans shall be cast on a separate on a long line beds.
CASTING YARD
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Casting yard include the following major items: Casting bed – 2 long line beds for casting segments of straight spans up to 28m. Casting bed – 1 long line for casting segments of curved/straight spans up to 31m. Moulds for casting of intermediate segments. Pier segment beds – 3 Nos.
1. Rebar tying area.2. Rebar Jig for Pier segment – 2 Nos. for each bed is 3x2 = 6 Nos.3. Rebar Jig for intermediate segment – 6 Nos. x2 for each segment (12 Nos.)
Batching Plant of capacity 60cumec per hour and cement silos (3 Nos. of 100 MT each)
Rebar yard Stores for aggregate, cement, pre-stressing material, general civil and
mechanical items. Laboratory. Office Blocks. Pedestals for general inspection/sleeve checking of segments. Sheds for keeping generator sets and miscellaneous activities. Survey Towers. Access Roads. Gantry 120 T capacity (1 Nos.) and 20 T capacity (2 Nos.).
LIST OF MOULDS AND EQUIPMETNS IN CASTING YARD
Sl.No. Description No.1 Long Line Casting Beds for Straight Span 22.25.28m 22 Long Line Casting Beds for Curved Span & 21m span 13 Casting Moulds for Pier Segment 34 Batching Plant 15 Transit Mixers 36 Goliath Crane with 120 T capacity 1
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7 Goliath Crane with 20 T capacity 28 Shutter Vibrators 89 Needle Vibrators As required
10 Concrete Pump 211 Curing Pump 212 Welding set 113 Total Station 114 Auto Level 1
MOULDS
There are three types of mould for casting for casting of segments:(a) Pier Segment Mould (A, B, C&D, for 31, 28, 25& 22m span).(b) 1. Intermediate Segment Mould for segment A2, B2, C2, D2.
2. Intermediate Segment Mould for segment A4, B4, A5, B5 and A6, B6 etc.Each mould comprises 4 major components – Bulkheads, Outer Shutters (Wing Forms). Bottom shutter and Inner shutters. Bottom Shuttering is supported on casting bed pedestals. Outer shutters are supported on a Movable Trolley. Reference may be made to the drawings for details.
SEQUENCE OF CASTING –LONG LINE BEDS
3 Long Line beds shall be provided, 2 beds for 22, 25 and 28m spans and one bed for 31m span and curved span. The width of the bed shall be 3m for straight span and 2.85m for curved span with wedge shaped beds in between depending on the radius of the curve. However both the beds can be utilized for casting of straight spans whenever required to do so.In a typical casting sequence of 31m span two pier segments shall be cast on two pier segment beds simultaneously and brought and placed on movable trolleys placed at their final locations on either side of long line bed. Two intermediate segments are match cast almost simultaneously starting from either end.The sequence of casting for spans less than 31m will be exactly same as mentioned for 31m span, except that for casting ofmid span segment one of its two neighbouring segments shall be lifted and re-positioned on the bed. Maintaining the correct length for the last segment to be cast. In doing so the outer shutter as well as inner shutter will overlap on the already cast segments on both sides, which shall be suitably adjusted in case of segments of length smaller than 300mm in exceptional cases as in curved segments.
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TIME FOR CYCLE CASTING
The time cycle for casting the pier segment/intermediate segments has been arrived at 45 hours/ 30 hours. To complete the casting of 31m span segments time taken has been arrived at 10 days.
REBAR JIG
Two rebar jigs for each type of intermediate segments (6 x 2 ) and two rebar jigs for each pier segments ( 2 x 3 ) shall be fabricated to meet the requirement of 40mm clear cover from all sides of concrete surface & 30mm for deck slab. Each casting mould shall have a dedicated jig which shall be provide cage fir their respective casting moulds. Additional one jig shall be provided as stand by intermediate segments which are comparatively more in numbers than pier segments. The jig be got checked at mutually agreed frequent intervals.
REBAR CAGE
The rebars shall be cut & bent by using cutting & bending machine at the centralized reinforcement yard adjacent to the casting yard as per approved BBS. The bars shall then shifted to the respective rebar jigs where they be tied by using GI using wire in required rebar cage at the required position as detailed in approved drawings. The sheathing shall be fitted inside the rebar cage at required position as detailed in approved tendon profile drawings and held in position using suitable chairs and hooks. The cage shall be lifted with a structural frame holding using suitable in manner to prevent any distortion while lifting and placing in a position inside the castling mould. The cage shall be lifted and placed in the casting mould by the 20 MT Goliath Crane. The Sheathing position shall be rechecked for profile.
COVER BLOCKS
The cover block shall be cast from the same grade of concrete as used in segment i.e. M-5-. The cover blocks shall be provided to ensure a clear cover of 40mm in the web and 30mm in the deck slab. These shall be cast and cured in advance to ensure that the cover block does not crush under the rebar weight while placing the cage in the casting mould.
CONCRETING
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The sequences of concrete shall be as follows:
1) Soffit Slab.2) Half height of web -1 + deviator block.3) Half height of web -2 + deviator block.4) Remaining height of wen -1.5) Remaining height of web -2.6) Deck Slab including Cantilevers on both sides.
The concrete with slump of 100+-25 mm shall be produced at centralized batching plant and transported to location by transmit mixers. The concrete shall be placed in sequence mentioned above by concrete pump. The concrete shall be vibrated by both shutters vibrators fitted to web shutter as well as needle vibrators of various diameter like 40mm, 60mm. Roughing of top flange and soffit slab of the segment shall be done in required where secondary pour is to be carried out.For separation of match-cast segments a suitable bond breaking material ( such as Concure WB from Forsroc ) shall be used on the surface of previously cast segment as approved by engineer.
FIXTURES IN SEGMENTS
All the fixtures such as drainage spout, flats for stray current arrangements, lifting holes, etc. shall be provided at specified location as detailed in the drawings.
GEOMETRY CONTROL & SURVEY PLATES
Two survey towers on wither ends of long line beds are constructed to exercise geometric control. Two plates size of 100mm x 100mm x 4mm shall be embedded along centre line of segment and two on each side of centreline.In casting by long line method the bottom shuttering is fixed to the pedestals as per actual soffit profile. Thus the only control required is matching of centre line along the crown top levels of the top flanges during subsequent casting operations.
CURING OF SEGMENTS
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Curing of concrete shall be complete and continuous with water. Minimum wet curing shall be for 14 days and up to 21 days from the date of casting.
DESHUTTERING
The shuttering shall be removed after the concrete has attained 20 MPa Crushing Strength. The internal form shall be collapsed using the turn buckles provided for movement of shutter. The outer form shall be released by the turn buckles and move outwards. The frame supporting internal and outer shutters shall be shifted to next location by moving it on rails.
LIFTING OF SEGMENTS
The match cast segments shall be fitted with a lifting frame through the lifting holes provided at the time of casting of the segment.The segment shall be lifted from the soffit shutter by the 120 ton capacity Goliath Crane and placed at the stacking yard. The lifting of segment shall be done after it attains minimum cube strength of 25 MPa.
PEDESTALS FOR GENERAL INSPECTION
These pedestals shall be utilized for inspection of pier segments dispatch to the site for erection. Pier segment requires thorough inspection in respect of anchorage cones, ducts, holes and bearing pedestals etc. which need to be cleaned before transportation to the site.
SAND BLASTING
Sand Blasting of segments shall be done on the pedestals. The purpose of sand blasting is to remove de-bonding agent and clear the segment of any laitance, dirt & foreign material, etc. just before transportation to erection site. Sand blasting be done gently just for 5 second so as to avoid any damage to the concrete surface. It shall be done by using combination of dry fine sand & compressed air through sand blasting equipment.
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NAMING OF SEGMENTS
The segments after casting shall be suitably named/numbered so as to identify the segments during launching. The numbering system shall be approved by the Engineer. The number such that it should consist the span no., segment type, length of span, date of casting, direction of segment in the span, etc.
HEALTH, SAFETY AND ENVIRONMENT
1) Only authorized equipment/personnel will be allowed within the area.2) All utilities shall be identified and protected.3) All lifting tools and tackles shall be periodically inspected against any damage.4) All workmen, supervisors and engineers shall use proper personal protection
gears.5) All employees shall follow the Project Health & Safety Rules.
QUALITY ASSURANCE AND QUALITY CONTROL
QA/QC shall be followed and maintained by complying with the procedure, relevant check list, sheet/formats.
ERECTION OF SEGMENTS
MAIN COMPONENTS OF LAUNCHING GIRGER
This section is build up as follows:
Main Box Girder
Front Support
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Middle Support
Rear Support
Rear Trolley
Slider Beams
Counter weight
Fixed Mounted Hoist
Platform / Walk ways
STEPS FOR AUTO LAUNCHING ALONG STRAIGHT SPANS
The term auto launching means forward movement of Launching Girder from already erected span to the next span to be erected.
Stage – 1
Step – 1 : Ensure that the erection of span if complete in all respects and the Launching Girder is ready for Auto Launching.
Step – 2 : Ensure anchoring of all the supports with anchor bars stressed to induce
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An initial tension of 10 tons per anchor bars.
Step – 3 : Bring the slider beams backward so that the last slider beam is as close as possible to mono strand jack bracket ( Near Rear Trolley ) and all other slider beams rests in succession at a spacing of 900mm towards Front Support.
Stage – 2
Step – 1 : Erect 90R rails over the newly erected span for further movement of Launching Girder.
Step – 2 : Remove the brakes provided at middle support by removing pins connecting monorail and the braking assembly.
Step – 3 : Check the Jacks of Rear Support and ensure that it experiences a minimum reaction of 20 tons +5/-5 tonnes (total reaction on four jacks ) on it.
Step – 4 : Close the Jack of Middle Support so that the reaction on the Jack of middle support is fully released. As a result of which, the reactions will be transferred on the Jacks of Rear Support and the Middle Support finally deactivated.
Step –5 : Open the anchors of Middle Support to allow its forward movement.
Stage – 3
Step – 1 : Move the Middle Support and positioned it over the Rear Pier Segment of newly erected span so that a distance of 1m is achieve between the expansion joint of the span and the centreline of the Middle Support.
Step – 2 : Open the Jacks of Middle Support to transfer reaction of 20 tonnes +5/-5 tonnes.
Step – 3 : Anchor the Middle Support.
Step – 4 : Apply brakes at Middle Support.
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Step – 5 : Remove the brakes provided at Rear Support by removing pins connecting monorail and the braking assembly.
Step – 6 : Close the Jacks of Rear Support so that the reaction on Jacks is fully released as a result of which the reaction will be transferred automatically over jacks of Middle Support and the Rear Support is finally deactivated.
Stage – 4
Step – 1 : Open the anchors of Rear Support to allow its forward movement.
Step – 2 : Move the Rear Support and position it over the pier segments so that a distance of 1m it achieved between centreline of expansion joint and centreline of the Rear Support.
Step – 3 : Anchor the Rear Support at its position.
Step – 4 : Open the Jacks of Middle Support to transfer reaction of 20 tonnes +5/-5 tonnes on it ensuring that the support is activated.
Step – 5 : Apply brakes at Rear Support.
Step – 6 : Remove the brakes provided at Middle Support by removing pins connecting monorail and the braking assembly.
Step – 7 : Close the Jacks of Middle Support so that the reaction on Jacks is fully released as a result of which the reaction will be transferred automatically over jacks of Rear Support and the Middle Support is finally deactivated.
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Stage – 5
Step – 1 : Move the Middle Support and position it over the pier segments so that a distance of 1m it achieved between centreline of expansion joint of the span and centreline of the Middle Support.
Step – 2 : Open the Jacks of Middle Support to transfer reaction of 20 tonnes +5/-5 tonnes on it.
Stage – 6
Step – 1 : Anchor the Middle Support.
Step – 2 : Attach longitudinal movement jack with the Middle Support.
Step – 3 : Remove the 100Φ pin provided in the telescopic leg of the Front Support using jacks provided over the bottom beam of Front Support.
Step – 4 : Close the jacks of Front Support and remove the jacks along with stools provided so that the reaction is fully transferred to the Middle Support
Step – 5 : Close the Telescopic Leg of Front Support to its minimum length and lock it in this position so that the Front Support hangs over the Launching Girder.
Step – 6: The shifting of Supports required to initiate Auto Launching in all respects after this stage, so that Launching Girder can be puller/pushed in the forward direction and onwards.
Stage – 7
Step – 1 : Remove the anchors of Rear Trolley to allow its forward movement.
Step – 2 : Unclamp the anchor plates of longitudinal sliding bearing of Middle Support and Rear Support if required so that the Launching Girder if guided by the Rollers during Auto Launching.
Step – 3 : Remove brakes provided in the Middle Support and Rear Support.
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Step – 4 : Start pulling/pushing the Launching Girder using longitudinal movement jack provided in Front/Rear side of Middle Support so that the Launching Girder slides over the Middle Support and Rear Support and Rear Trolley moves along with the Launching Girder on rails provided along the erected span.
Step – 5 : Continue pulling/pushing of Launching Girder until the Rear Trolley reaches close to the Rear Support so that further movement is not possible.
NOTE : A minimum clear distance of 300mm between Rear Trolley and Rear Support must be ensured.
Stage – 8
Step – 1 : Anchor the Rear trolley with the help of HT bars stressed to induce minimum initial tension of 5 times per anchor then remove anchors of Rear Support.
Step – 2 : Lower the Jacks of Rear Support and move Rear Support and positioned it over S - 3 segment.
Step – 3 : Anchor the Rear Support at this location.
Stage – 9
Step – 1 : Remove the anchors of Rear Trolley then start pulling/pushing Lauching Girder again using longitudinal movement jack provided in Front/Rear side of Middle Support so that the Front Support reaches the next Pier location.
Stage – 10
Step – 1 : Open the Telescopic Leg of the Front Support so that the bottom beam of Front Support rests over the concrete Pedestal.
Step – 2 : Anchor the Front Support over Pier Cap by tightening anchor bolts in the sleeves provided in the Pier Cap .
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Step – 3 : Move Slider beams in forward direction and place them as per the erection sequence of the new span to be erected.
Step – 4 : Apply brakes at Rear Support using Braking Assembly provided at Rear Side of Rear Support.
Step – 5 : Tighten the vertical HT Stress bars provided at top Beam of Rear Trolley to ensure that there is no possibility of relative movement between top beam of Rear Trolley and Launching Girder during erection of next span.
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MISCELLANEOUS
ELASTOMERIC BEARING
Isomeric view of Elastomeric Bearing
Section through Bearing
INSTALLATION INSTRUCTION
1) Care shall be taken in packing, transportation, storage and handling to avoid any mechanical damage. Contamination with oil, grease and dirt, unique exposure to sunlight and water.
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2) The position of the bearings shall be accurately marked on Pier/Abutment Cap and the area where the bearing will be seated accurately levelled.
3) The concrete surface shall be free from any loose material and clean of any grease, oil, paint, etc. and it shall be dry at the time of fixing of bearing.
4) Bearing must be placed between two horizontal surface ( maximum tolerance 0.20% perpendicular to load ) and at true plant position of their control lines marked on receiving surfaces shall be free from local irregularities ( maximum tolerance + 1mm in height ).
5) Box girders shall be lowered on bearing only after the completion of stressing and grouting operation at the time of stressing operation, end segment of box girder shall be seated over temporary bearings.
MAINTENANCE
1) The bearing shall be subjected to planned maintenance care.2) The exposed bearing surface shall be maintained clean and free from
contamination with grease or oil, etc.3) Annual routine maintenance inspection or special maintenance inspection of
all bearing shall be made to check for any surface cracking or science of damage, deterioration or distress.
4) Damaged bearing shall be replaced immediately to avoid to differences in stiffness, all adjacent bearing on the line of support shall also be replaced and uniform seating of main girder over all the new bearing shall be ensured.
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