SECTION 72 CAST-IN-PLACE PILES Contents Page 72.001 Cast-in-place piles generally 2 72.002 Dimensions of piles 2 72.003 Boring 2 72.004 Reinforcement 3 72.005 Placing of concrete 3 72.006 Pile head casting level tolerances 3 72.007 Grouting of piles 4 72.008 Disposal of excavated material 4 72.009 Additional requirements for underpinning 4 72.010 Driving piles 4 References 6 British Standards 6 Model Clauses 6 Other Publications 6 Page 1 of 6
SECTION 72 Cast-in-place piles generally (B3.1, B4.1, B5.1) CAST-IN-PLACE PILES 72.001 Delete ICE Specification, clauses B3.1, B4.1 and B5.1, and the following shall apply. Materials and workmanship for cast-in-place piles shall be in accordance with Section 70 (General requirements for piling), Section 80 (Structural concrete) and ICE Specification sections B3, B4 or B5, as amended by this Section of the Model Clauses. Where such requirements conflict ICE Specification sections B3, B4 or B5, as amended by this Section of the Model Clauses shall take precedence. Unless specified otherwise in Appendix 72/1, the grade of concrete to be used in the piles shall be determined by the Contractor as part of the pile design. The Contractor shall demonstrate that allowances have been made in his design for long-term changes in concrete properties caused by shrinkage and creep. Dimensions of piles (B1.10.2) Boring (B3.5.5) Casings (B3.3.2, B5.4.1) 72.002 Unless specified otherwise in Appendix 72/2, the Contractor shall define the proposed pile diameter as in ICE Specification, clause B1.10.2. 72.003 In addition to ICE Specification, clause B3.5.5, pile bores shall be exposed for the minimal period practicable, and shall be covered when work is not in progress. The ingress of surface water, track ballast or other foreign objects into the pile bore shall be prevented. Unless specified otherwise in Appendix 72/3, the Contractor shall provide details of all temporary and permanent casings - these should be fit for purpose as defined in ICE Specification, clauses B3.3.2 and B5.4.1. Notwithstanding the requirements of ICE Specification, clause B3.3.2, for work on or near the line, temporary or permanent casings shall not be left higher than the top of sleeper level on completion of the absolute possession for installation, and any open casing shall be backfilled. In ICE Specification, clause B3.5.1, insert as amended by Section 70 (General requirements for piling) after clause B1.13. Spillage and disposal of support fluid (B18.7) In addition to ICE Specification, clause B18.7, any track ballast contaminated by drilling fluid shall be replaced with new track ballast and the Permanent Way made good. Page 2 of 6
Pumping from pile bores (B3.5.4) Cleanliness of pile bases (B3.5.7) Reinforcement (B3.4.1, B4.4.7) Placing of concrete (B3.5.2.3, B5.4.8) Concrete mix design and workability Compaction (B3.5.2.2) Further to ICE Specification, clause B3.5.4, where pumping from pile bores is permitted, the stability of the Permanent Way shall not be affected by the pumping, and track ballast shall not be contaminated by the pumped water. In addition to ICE Specification, clause B3.5.4, filters shall be provided to all pumping equipment to inhibit the removal of fines from the surrounding soils. Further to ICE Specification, clause B3.5.7, for piles of 750 mm diameter or greater, and where the pile bore contains water or drilling fluid, the base of each bore shall be cleaned using an airlift method acceptable to the Employer s Representative. 72.004 Further to ICE Specification, clauses B3.4.1 and B4.4.47, where Option 1 Engineer design under ICE Specification clause B1.4 applies, the minimum length of reinforcement shall be as detailed in Appendix 72/4. 72.005 In addition to ICE Specification, clauses B3.5.2.3 and B5.4.8 as applicable, except where piles are constructed using continuous flight augers, concrete shall not be placed in any pile bore without the agreement of the Employer s Representative. Concrete placed in continuous flight augers shall comply with Section 80 (Structural concrete). Further to ICE Specification, clause B3.5.2.2, when the bore is dry the top 1.5 metres of the pile below final level shall be vibrated. The method of working shall be such that fines are not washed away from the concrete of unset piles. Pile head casting level tolerances (B1.10.3, B5.4.11) 72.006 Further to ICE Specification, clauses B1.10.3 or B5.4.11 as applicable, the top of the pile shall be above the finished level of the pile head shown on the Contract Drawings and the surplus removed to provide a satisfactory bonding of the pile head to the structure. For piles constructed on or near the line, and where the pile head level is below the commencing surface, an additional casting tolerance to that specified in ICE Specification, table B1.5 shall be provided to prevent the pile head concrete from being contaminated by the backfill. Page 3 of 6
Temporary backfilling above pile casting level (B1.10.3) Grouting of piles (B3.5.11.1) Disposal of excavated material Additional requirements for underpinning Further to ICE Specification, clause B1.10.3, open bores on or near the line shall be backfilled with clean spent ballast. The method of placing the backfill shall be such that the pile concrete below pile head level is not contaminated. 72.007 Further to ICE Specification, clause B3.5.11.1, the necessity and requirements for piles to be pressure grouted shall be determined by the Contractor as part of the pile design. 72.008 Disposal of excavated material shall be in accordance with the requirements of Appendix 72/5. 72.009 Boring equipment shall be suitable for drilling through concrete and masonry without causing harmful disturbance or vibration to the existing structure. Underpinning piles shall be constructed without damaging previously formed piles or adjacent structures, and without loss of ground from below existing structures or the ingress of drilling fluid into adjacent drains or track bed. Driving piles (B5.4.3) Driving records (B5.5.1) 72.010 As stated in ICE Specification, clause B5.4.3, pile installation and procedures shall be in accordance with clause B1.14 except where acceptable evidence is provided to the Employer s Representative of the suitability of alternative equipment or methods. ICE Specification, clause B5.5, requires that clause B1.12 is met regarding the supply of records for each pile. With the agreement of the Employer s Representative and unless stated otherwise in Appendix 72/6, the percentage of piles for which full records are required may be reduced but to not less than 10% of the total number of piles. Redrive checks in ICE Specification, clause B1.14.1 are required. Set (B1.14.3) Driven sequence and risen piles (B1.14.4) Delete ICE Specification, clause B1.14.3, sub paragraph (e). In ICE Specification, clause B1.14.4, paragraphs 3 and 4, delete once a week and insert at commencement of each day s or shift s work following piling. Where redriving is to be carried out, a revised sequence of piling shall be submitted to the Employer s Representative for acceptance. Full driving records shall be provided for all piles required to be redriven. Page 4 of 6
Should the Contractor propose to utilise jetting to ease pile driveability in cohesionless soils, such jetting shall be carried out in accordance with BS EN 12699. Page 5 of 6
REFERENCES This is a list of publications referred to within this Section of the Model Clauses. British Standards Title Issue date BS EN 12699 Execution of special geotechnical work. 2001 Displacement piles. Model Clauses Issue date 50 General requirements for earthworks and 02/96 excavations 70 General requirements for piling 03/10 80 Structural concrete 08/08 Other Publications Title Issue date Thomas Telford Services ICE Specification for piling and embedded 2007 Ltd retaining walls. 2 nd Edition. Page 6 of 6