SCOPE OF WORK FOR PILING JOB

Transcription

1 SCOPE OF WORK FOR PILING JOB

2 1.0 PURPOSE This document defines the scope of works and specific requirements for the tank pad construction including pile foundation system for the proposed tanks at Wadala terminal, Mumbai. 2.0 CODES, STANDARDS & SPECIFICATION a. IS: 2911 (All Parts) b. Specification for materials for Reinforcement concrete piles c. Specification for construction and installation for bored cast in situ piles d. Specification for testing of concrete piles 3.0 SCOPE 3.1 General Providing RC bored cast in situ piles and R.C. pile caps as per design carried out by the bidder, vetted by any approved government engineering college/ renowned structural consultancy firms and submitted to HPCL for review before starting of pile foundation job and anti corrosive layer, including good earth filling and related earth works to provide tank pads for the proposed tanks, all jobs complete within the specified time period mentioned in the tender. Supply of all materials is also included in contractor s scope. The scope in general consists of designing the RCC pile foundation basis the soil investigation report/ recommendation for the boreholes carried out at tank no 81 & 82. The soil investigation is being carried carried out by HPCL through another agency and shall be handed over the party after award of this contract. The party has to carry out the design of the pile foundation basis the soil report for tank 81 & 82 after the award of the contract and get the design vetted by any approved government engineering college/ renowned structural consultancy firms within the quoted rates. For the purpose of providing techno commercial offer for this tender by the prospective bidders the soil data available with HPCL for tank nos 93, 94 & 95 at Wadala Terminal where tanks on pile foundation has been recently constructed. and the brief details are as under: Three bore holes were carried out for the three tanks and all the boreholes were terminated between M and M and the type of soil encountered for the three boreholes are provided below: Borehole No Depth of termination Type of Soil Encountered BH 1(Tank 93) Fresh greenish grey BASALT with white infillings BH 2(Tank 94) Slightly weathered greenish Grey BASALT with white infillings BH 3(Tank 95) Moderately to slightly weathered reddish grey BASALT with white infillings For the purpose facilitating the bidders to provide their techno commercial offer the diameter of piles have been assumed as 800 mm dia and depth of termination in line with design and construction carried out for tank nos 93, 94 & 95. The job description for pile foundation job has been itemized in the schedule of rates considering 800 mm diameter pile and length as per the above termination depth to enable the bidders to quote. The quantities mentioned in the schedule of rates are approximate and actual payment shall be made basis the actual executed quantities based on the approved design.

3 The vetted design shall be submitted to HPCL before starting the piling work. The testing of piles shall also be carried out by the contractor in line with IS 2911 (Part IV) and relevant specifications of this tender document within the quoted rates. No extra payment shall be made to the Bidders on this account. However the contractor is expected to quote for this tender based on the information provided herein and other sections of this tender document including the Schedule of Quantities. 3.2 Minimum Requirement of Piling Equipment Sufficient no of hydraulic self propelled or manual rotary piling rig complete with casing Adaptor and Casing Oscillator to complete the entire job as per the time schedule provided in this tender document.. The Contractor shall mobilize sufficient spares; cutting tools (e.g. flat teeth bits, round shank bits, holders, etc) to avoid any stoppage of work. 3.3 Tenderer s shall submit the following information as part of their technical bid: i) Numbers of the piling rig proposed to be deployed. ii) Full Technical details of piling rigs and accessories in the form of catalogues, data sheets, etc. iii) Piling procedure, piling programme and accessories to be mobilized by the contractor at no extra cost to the client. 3.4 The contractor shall use only Ready mixed concrete for the proposed piling and pile caps works. Contractor shall indicate the resources available in this regards including number of batching plants to be mobilized considering the time frame and nature of works. As a specific requirement, only Portland slag cement conforming to IS 455 shall be used for all concrete works. All rebars shall be Corrosion resistant steel (Tiscon CRS/SAIL-HCR- /RINL-HSCR) and shall conform to IS 1786 grade Fe 415 for mechanical properties. 3.5 The work involves but not limited to the following: a) Construction of straight shaft RCC bored cast-in-situ piles of approved diameter and depth of termination below cut-off level depending on occurrence of founding strata i.e. soft / disintegrated, medium hard or hard rock strata (basis approved design carried out by the bidder based on soil investigation report for tank 81 & 82 to be handed over the bidder after award of work order) and approximate number of piles b) Carrying out of initial load tests on test piles specifically installed for the purpose and routine load tests as specified on randomly selected job piles selected by Engineer-in-Charge. 4.0 AVAILABLE INFORMATION 4.1 As per piping requirement, the pile cap is proposed to be placed at about 1.0m above the existing ground level. Hence, for installation of pile the ground level of the proposed Tank area including at least 2.0m beyond the Tank periphery shall be raised upto 1.0m above the existing ground level. The filling shall be done with good quality murrum collected from borrow area to be arranged by the contractor. The filling shall be done in layers not exceeding 300 mm loose thickness and compacted to minimum 90% standard proctor density. Before installation of the pile cap, soil filled up in the tank area and beyond above pile cap level shall be disposed as per instruction of Engineer-in-Charge. Soil below the pile cap level shall be compacted well before laying PCC for Pile cap. 5.0 REQUIREMENTS All work shall be carried out in accordance with the specifications enclosed herewith and contractor shall ensure minimum requirements as laid down hereunder: 5.1 Termination of Piles Piles shall be terminated with a minimum embedment of 2.40m inside the soft /disintegrated rock layer having SPTN Value more than 100. After encountering the soft /disintegrated rock layer, the beginning

4 of the layer shall be established by conducting SPT. In case SPT is observed more than 100, the pile shall be terminated with an embedment of minimum 2.4m inside the strata. For confirmation of the similar strata two more SPT shall be conducted thereafter with an interval of 1.0m, conducting of SPT shall be done at least one in five (1 in 5) pile location. In case medium hard / hard rock encountered before minimum embedment depth in the above specified rock strata the pile shall be terminated in this rock layer with a minimum embedment of 500mm in medium hard rock or 200mm in hard rock strata. Piling in soft / disintegrated rock shall be done preferably with chisel as per discretion of Engineer-in- Charge and in the case of medium hard / hard rock strata pile boring shall be proceed with chisel of weight 2.5t or more. The level of encountering the rock layer and termination depth in all cases shall be certified by Engineer-in-Charge. 5.2 Safe Load Carrying Capacity For Vertical Compression/Lateral/Uplift The tenderer shall guarantee minimum safe load of 1.5 times the design capacity for the piles provided. The safe load may be increased by 25% in the case of wind and seismic. 5.3 MATERIALS Materials shall conform to specifications for materials for Reinforcement concrete pile which is enclosed elsewhere in this tender document and forming a part of the tender CONCRETE The concrete shall have a minimum strength of 30 N/sq. mm at 28 days. The cement for concrete shall be Portland Slag cement having minimum cement content not to be less than 400 kg / cu.m with maximum water-cement ratio of 0.5. The allowable slump shall be as per relevant latest revision of IS codes (IS 2911 Part 1/Sec 2). The Engineer-in-charge may allow marginal adjustment in water/cement ratio to obtain concrete of good workability. The other concrete specifications shall be as per relevant clauses of Design, Construction & Installation of Bored cast-in-situ piles forming part of this tender REINFORCEMENT Reinforcement shall conform to IS: 1786 (latest version) grade Fe-415 for mechanical properties. The reinforcement in the pile shall consist of the following: a) Longitudinal/Ties/Spacer bar Reinforcement Reinforcement provided shall be as per approved design with respect to diameter, numbers and should run through the entire length of the pile. d) Cover Clear cover to reinforcement shall be as per approved design (min 75mm). 5.4 INSTALLATION Installation of piles shall be carried out in accordance with the pile lay out drawings which shall be available to the contractor at the time of execution of work Cut-off level of the piles shall correspond to those given in the working drawings To ensure dense and sound concrete upto cut-off level, concreting shall extend minimum 750 mm above cut-off level. However, no extra payment shall be made for this and quoted rates shall be inclusive of this In case the reinforcement cage is made up of more than one segment, the same shall be assembled by welding only, before lowering, as per IS: by providing necessary laps The vertical reinforcement shall project 50 times its diameter above the cut-off level Pile shall be constructed by using temporary casing upto minimum 1.5m to 2.0m inside the stiff to very stiff clay exists below very soft / marine clay. Adequate bentonite mud shall be used in case full depth temporary casing not been used during the boring below temporary casing. Concrete shall be placed by tremie. All precautions for obtaining clean and sound pile shaft shall be strictly observed.

5 5.4.7 For Tremie concreted piles, a sample of drilling fluid shall be taken from the base of the borehole by means of an approved sampling device in the first few piles and at suitable interval of piles thereafter. Concreting shall not proceed if density of fluid exceeds 1250 kg/cu.m. The sand content in the fluid shall not exceed 7 percent. 5.5 MEASUREMENT OF PILES The piles shall be measured and paid for the actual pile length from pile tip to the cut off level, as per the approved working drawings submitted by the contractor based on the approved design or as indicated by the Engineer-in-Charge. No extra payment shall be made for empty boring Payment for routine load tests which shows unsatisfactory results shall not be made Piles showing unsatisfactory results shall be treated as defective piles. Defective piles shall be removed or left in place and replaced by additional piles as directed by engineer-in-charge at no additional cost to the owner Reaction piles, if required for the purpose of conducting load tests on piles shall not be paid extra. Quoted rate for tests shall be inclusive of this. However, for routine lateral and uplift tests, if required, job piles may be used as reaction piles The quoted rate for bored cast in situ piles shall be inclusive of reinforcement conforming to IS 1786 Fe 415 corrosion resistant bars of TISCON CRS, HSCR from Vizag steel or HCR from SAIL. However measurement/payment for reinforcement used in piles shall be made through a separate item available in the schedule of rates. 5.6 PILE TESTING Initial Load Test i) Prior to commencement of the job piling, initial load tests shall be done. ii) The tenderer shall be allowed to proceed with job piling only after successful completion of the initial tests to the satisfaction of the Engineer-in-Charge. Location of the test piles shall be approved by the Engineer-in-Charge. The no. of such tests is given in the schedule of quantities Routine Load Test Routine load tests shall be carried out up to one and half times the design load. The piles for the test shall be randomly selected by the Engineer-in-Charge Pile Load Test Details i) For pile load tests, the test set up shall be as per IS 2911 Part IV and specifications for testing of concrete piles. ii) All testing shall be done by Direct method of loading in successive increments as per the relevant clauses of IS: 2911 Part IV & Standard Specifications for testing concrete piles forming a part of this tender iii) Each stage of loading shall be maintained till the rate of movement is less than 0.2 mm per hour. Test shall be carried out at the cut-off level Maximum test loads shall be as follows: i) Initial pile load tests: load corresponding to a total settlement of 10% of the pile diameter or three times the safe load whichever occurs earlier. ii) Routine vertical load test: Load corresponding to 12 mm settlement or one and half times the safe load whichever occurs earlier Number of Tests Required The number of tests required shall be as per relevant clause of IS 2911 Part IV Payment for testing of Piles No additional payment shall be made for testing of piles. The rates quoted in the schedule of rates shall deem to be inclusive of the pile testing required to be carried out under clause 5.6. NOTE: Kentledge load shall be at least 25% higher than the maximum test loads.

6 5.6.5 Criteria for Assessment of Safe Loads Safe vertical load on single pile shall be the least of the following: i) Two thirds of the final load at which the total settlement attains a value of 12 mm. ii) 50% of the final load at which the total settlement equals to 10% of the piles dia. iii) Safe lateral load on single pile shall be least on the following: iv) 50% of the final load at which the total lateral displacement equals to 12 mm. v) Final load corresponding to the total displacement of 5 mm A full record of pile load test results shall be submitted in triplicate to the Engineer-in-Charge immediately on completion of each test. The record shall also include the plots of load-settlement (for various stages of loads) characteristics of pile and also the interpretation of the pile load test curve as per criteria for safe loads mentioned in the specifications for testing concrete piles forming a part of this tender. Any special observations shall be duly explained by the contractor.