GENERAL REQUIREMENTS FOR PILING

Transcription

1 SECTION 70 GENERAL REQUIREMENTS FOR PILING Contents Page General Pile layout, design and construction Information to be supplied with the Tender Safety Forcible corrections to piles Piling on or in close proximity to the tracks Work Package Plan Piling programme Records Record drawings Nuisance and damage Supervision and control of the piling works 7 References 8 British Standards 8 Railway Group Standards 8 Model Clauses 8 Other Publications 8 Page 1 of 8

2 SECTION 70 GENERAL REQUIREMENTS FOR PILING General The whole of the piling work shall comply with the information shown on the Contract Drawings and shall be constructed in accordance with the relevant sections of the ICE Specification for piling and embedded retaining walls (2nd edition, 2007), hereinafter referred to as the ICE Specification, unless qualified or amended by the following Clauses. Clause numbers in parentheses within the heading margins refer to the corresponding clauses in the ICE Specification. Pile layout, design and construction (B1.4) Further to ICE Specification, clause B1.4, Option 2 shall apply unless otherwise specified in Appendix 70/1. Except where shown on the Contract Drawings, the pile type, pile size, and pile positions and spacing shall be selected and determined by the Contractor. The piles shall be designed in accordance with the recommendations of BS EN and the NA to BS EN ; Non-Contradictory Complementary Information (NCCI) in BS 8004; the requirements of Appendix 70/1; and the following: i) the permitted vertical and horizontal pile head deflections for the specified design verification loads shall be in accordance with Schedule 70/A, for the purposes of calculating horizontal deflections, the fixity of the pile heads shall be as shown on the Contract Drawings. In addition, for helical screwed piles: i) design shall be based on conventional soil mechanics, i iv) long-term tension loads in cohesive soils shall be checked using drained soil strength parameters, in the design of radio mast equipment support structures, the wind loading component on a pile shall not exceed 25% of the ultimate tensile resistance of that pile, the basis of the relationship between the pile capacity and measured values of torque shall be demonstrated in the design, Page 2 of 8

3 v) a minimum of two helices shall be provided on every pile, and a minimum of three helices where pile capacity is dependent on the strength of variable soils - such as non-engineered fill and inter-bedded soils, vi) creep of the piles shall be considered in the design. For the purposes of the Tender only, the soil parameters used for the design of the piles shall be those given in the Contract. Where Tenders propose alternative soil parameters for design they shall justify and gain the Engineer s approval prior to adopting these alternatives. The Employer s Representative shall be provided with drawings showing the pile design and the pile arrangement. The number of copies shall be as detailed in Appendix 70/1. A completed Certificate of Design and Checking shall be provided for the pile design in accordance with RT/CE/S/003. Information to be supplied with the Tender (B1.4, B1.10) In addition to the requirements of the ICE Specification, clauses B1.4 and B1.10, the following shall be supplied with the Tender: i) details of the type of pile offered, including any permanent casing, i iv) the method to be adopted for calculating and checking the load bearing capacity, pile settlement and horizontal pile head deflection, details of the tests proposed to be undertaken on the Site to prove the pile design, including any proposed trial drives or bores, and the name of the specialist contractor proposed for undertaking the non-destructive testing of the piles, where friction reduction is specified (but no particular method is detailed) or where friction reduction is required by the Contractor s design, the type and description of the method to be used to reduce friction on the piles, and the numbers and lengths of piles to be so treated, v) details of preboring or other methods of aiding pile driveability considered necessary by the Contractor, including the locations, diameters and depths below the commencing surface of any preboring, vi) the names of the organisations proposed for the design and design check, Page 3 of 8

4 v the name of the specialist contractor proposed for the piling work including details of the contractor s relevant experience and successful usage of the proposed piling system for the particular ground conditions at the Site. Safety (B1.6) Forcible corrections to piles (B1.8.2) Piling on or in close proximity to the tracks (B1.10) NR/GN/CPR/401 provides guidance on contractual health and safety requirements In addition to ICE Specification, clause B1.8.2, where the Contractor considers that forcible corrections to steel piles are required, full details of the Contractor s proposals to carry out such corrections shall be submitted to the Employer s Representative, and the Employer s Representative s acceptance of the method and agreement that forcible corrections are necessary shall be obtained before such work commences No excavation shall be permitted in the track formation to provide access for the piling hammer during driving, and accordingly an additional pile length or the use of a long dolly shall be allowed for to give the required penetration. Unless shown otherwise on the Contract Drawings, piles left protruding from the track formation shall not infringe standard clearance as defined in GC/RT5212. Any pile driven within the sleeper area of the track shall be cutoff at a minimum of 300 mm below the underside of sleeper level. Any such pile incompletely driven shall subsequently be driven to the correct depth after making a butt jointed connection that is acceptable to the Employer s Representative. For piles constructed within the ballasted area of the track, on completion of each absolute possession the track and ballast shall be reinstated to provide the track construction standards specified in RT/CE/S/102. Work Package Plan (B1.10) Further to ICE Specification, clause B1.10, a Work Package Plan for the piling works shall be submitted to the Employer s Representative for acceptance. The programme for submitting this Plan shall be as detailed in Appendix 70/2. The Plan shall include further details of the information submitted in accordance with ICE Specification clause B1.10 and the associated guidance in C1.10 and, as necessary, shall include the following: i) calculations, drawings and design and design check certification based on the analysis model, referred to in Clause , for all elements of the piling works including any associated Temporary Works, Page 4 of 8

5 i iv) the piling sequence - to demonstrate that the uplift and lateral displacement of driven piles or the integrity of cast-in-place piles will not be affected, details of the proposed piling plant and equipment - in sufficient detail to demonstrate the suitability of the plant for achieving the required penetration, and for working within the noise and vibration limits specified in the Contract - and the position of such plant relative to the tracks, setting out and means of achieving specified tolerances, v) the length of temporary casing or use of support fluids to maintain adequate support for the ground during pile construction, vi) v periods required for boring and concreting - so that the pile resistance that can be mobilised can be verified, the method and equipment for cleaning or forming the base of the pile where end bearing resistance is assumed to be developed in the design, vi the method proposed to be used by the Contractor to verify pile depth, bore stability, base cleanliness and compliance with the specified tolerances, ix) the method of placing concrete to check (a) that concrete is placed vertically down the bore without segregation, and (b) that a description of the method used to place concrete using a tremie is available where concrete is to be placed under water or support fluid, x) the frequency and means of testing concrete workability, concrete strength (where applicable), and compliance values for grout, xi) x the means of placing reinforcement including lapping of any cages, the method of maintaining concrete cover, cage verticality, and details of any additional reinforcement for lifting, handling and placing, details to show how casings, permanent or temporary, are to be maintained in position during concreting, xi full details of preboring or other methods of aiding pile driveability, and measures taken to minimise disturbance of the ground, Page 5 of 8

6 xiv) the level to which concrete is to be cast, and details of how completed piles will be protected against damage during subsequent works, xv) procedures for dealing with unplanned situations, such as loss of support fluid, obstructions, unexpected ground conditions, and piles out of tolerance, xvi) details of all instrumentation and monitoring equipment proposed to verify that the specified tolerances are being achieved. The piling works shall not commence until the Work Package Plan has been accepted by the Employer s Representative. Piling programme (B1.11) Records (B1.12) In ICE Specification, clause B1.11, delete 24 hours notice and insert the minimum period of notice specified in Appendix 70/3. In ICE Specification, clause B1.11, programme shall be deemed to include piling sequence and the timing for driving or boring piles having regard to the avoidance of damage to adjacent piles In addition to the records specified in ICE Specification, table B1.6, the following information shall be provided: i) All piles a) designed working load, b) where appropriate, levels and measurements to determine ground heave or movement of any pile resulting from the piling operation. i iv) Driven precast concrete, steel or timber piles a) details of type and positions of joints. Cast-in-place piles a) method used. Concrete piles a) concrete mix details - including concrete grade, nominal maximum aggregate size, cement content, water/cement ratio, details and quantity of any admixtures or cement replacement materials used, b) reinforcement details - including number, type and size of main reinforcement bars, type and size of helical or line bars, reinforced length of pile. v) Helical screwed piles a) torque installation records and torque monitoring calibration data. Page 6 of 8

7 When any unexpected driving or boring conditions are encountered the Employer s Representative shall be informed. Details of all obstructions, delays and other interruptions, including the actual time spent in overcoming the unexpected conditions, shall be agreed with the Employer s Representative and recorded as the work proceeds. Record drawings In addition to the requirements specified in the Contract for record drawings for piles designed by the Contractor, on completion of the piling work, two copies of the drawings showing the piles as constructed shall be provided to the Engineer for approval. Upon approval, copies of these drawings shall be provided as specified in Appendix 70/4. Nuisance and damage (B1.13.1) Further to ICE Specification, clause B1.13.1, the piling shall be carried out within the noise limits specified in Section 10 (General). The Contract may specify requirements for carrying out piling works during absolute possessions, and place restrictions on permissible working hours. (B1.13.2) Supervision and control of the piling works (B1.15) Existing adjacent structures and services shall not be damaged during the execution of the piling works. The Contractor shall submit estimates of the vibration levels generated by the piling operations and whether it is proposed to monitor vibration levels during the works Further to ICE Specification, clause B1.15, Contractor s personnel whom the Contractor considers competent to supervise the piling shall be capable of recognising and assessing unexpected ground conditions, or any potential dangers (such as noxious or dangerous gases), as they might arise. The Contractor shall submit his Quality Plan in accordance with the programme requirements detailed in Appendix 70/5. Page 7 of 8

8 REFERENCES This is a list of publications referred to within this Section of the Model Clauses. British Standards Title Issue date BS 8004 Code of Practice for foundations BS EN Eurocode 7. Geotechnical design. General 2004 rules. NA to BS EN UK National Annex to Eurocode 7: Geotechnical design - Part 1: General rules Railway Group Standards Title GC/RT5212 Requirements for defining and maintaining clearances. Issue date 02/03 Network Rail standards Title Issue date NR/GN/CPR/401 Guidance on contractual health and safety 12/08 requirements. RT/CE/S/003 Technical approval of design, construction and 02/04 maintenance of civil engineering infrastructure. RT/CE/S/102 Track construction standards. 02/02 Model Clauses Title Issue date 10 General 08/08 Other Publications Title Issue date Thomas Telford Services ICE Specification for piling and embedded 2007 Ltd retaining walls. 2 nd edition. Page 8 of 8