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Technical Requirements for all Permanent Piling Works

1.         PURPOSE

 

1.1       This engineering specification defines the requirements for all permanent piling works.

 

 

2.         scope

 

2.1       This specification applies to all permanent works for plants designed by Air Products Europe.

 

 

3.         related documents

 

3.1       Air Products Engineering Documents

 

4ECE-M10  Concrete and Reinforcement

 

3.2       British Standards Institute (BSI)

 

BS 8004     Code of Practice for Foundations

 

Note:  The works shall be in accordance with the above documents. However, outside the U.K., the codes of practice of the country in which piling takes place may be substituted.

 

 

4.         DESCRIPTION OF WORK

 

               The design supply, installation, and testing of piles to withstand the loadings described on the drawings.

 

               The provision of all plants required for the handling and installation of vertical and raking piles, including any plant which may be required for loading and testing, and for dealing with damaged or misplaced piles.

 

               Any earthworks that may be required to complete the work as described, including the removal of spoil.

 

               Any additional site preparation that may be required, including the supply of materials and labour for access and hard-standings. The Contractor shall visit the site to determine the exact extent of this requirement.

 

               Pile testing as described in the contract documents or as instructed by the Engineer’s Representative.

 

   Pile installation and testing records (see Clause 15).

 

 

 

  1. TYPE OF PILE AND DESIGN

 

5.1       Each pile shall be designed to carry the full working load plus any loads due to negative friction, plus an adequate factor of safety. The loads shown on the drawings exclude any load factors. Design shall be to local codes of practice.

 

5.2       The Contractor shall submit with his tender the following:

 

The estimated pile length.

 

Type and diameter of pile, together with full details of construction.

 

Materials of construction including quality of reinforcement, type of steel, concrete quality and type of cement.

 

The Contractor’s calculations proving the length used to determine the pile working

load.

 

Note:  The calculations shall clearly show the factors of safety and/or partial load/material    factors used in the design. The calculations shall also include the anticipated pile set for   driven piles.

 

5.3       Piles shall be designed and constructed with sufficient extra length to allow the piles to be broken down to the cut-off level at a later date, and joined to the pile cap without damage.

 

5.4       Reinforcement shall be of sufficient length beyond the cut-off level to ensure full tension anchorage into the pile cap.

 

5.5       The piles shall be designed and made so that no hooks, lifting loops, or any metal projects from the finished concrete that could corrode and spoil the concrete.

 

 

  1. WORKING CONDITIONS

 

6.1       The Contractor shall report immediately to Air Products any circumstances which indicate that the ground conditions differ from those expected from the soil survey, to the extent that the bearing capacity of the piles may be materially affected.

 

6.2       The order of constructing piles shall be agreed with the Engineer’s Representative before commencement of work. The Contractor shall only vary this order in accordance with instructions received from the Engineer’s Representative.

 

6.3       The Contractor shall provide sufficient rig(s), plant, labour, and materials to complete the work within the specified period.

 

 

  1. DRIVEN PILES

 

7.1       Prior to commencing work, the Contractor shall confirm and agree the pile set with the

Engineer.

 

7.2      Closely spaced piles in groups shall be driven commencing with the centre pile and working

outwards, or in such order approved by the Engineer’s Representative, to ensure minimum interaction between the driven piles and the pile being driven.

 

7.3      The Contractor shall, if instructed by the Engineer, redrive any piles which may have risen in level or may be suspected of having been affected by any pile driving operation in the vicinity. Redriving shall be to the original agreed set or depth.

 

 

7.4      The Contractor shall, at all times take all necessary precautions to prevent damage to piles. The heads of piles shall be protected with a helmet of a type approved by the Engineer. All piles cracked or otherwise damaged during handling or driving shall be repaired or replaced. Alternatively, if required by the Engineer, additional piles shall be supplied and installed at the Contractor’s expense.

 

7.5      Concrete piles shall not be driven until at least 28 days after casting, unless agreed by the Engineer.

 

7.6      The Engineer’s Representative shall be notified 24 hours before the commencement of driving. Piles shall be driven to the set or depth approved by the Engineer. The Engineer’s Representative shall be informed at least one hour before the set is taken.

 

  1. CAST-IN-PLACE PILES

 

8.1      When practicable and unless otherwise agreed by the Engineer, all pile excavations or casings shall be inspected for their full length before concreting. The Contractor shall provide all the apparatus necessary for the inspection.

 

8.2      Precast concrete sections or steel tubes in which concrete is to be placed shall be free from damage before being installed.

 

8.3      Reinforcement shall be maintained in its correct position during concreting of the pile. When it is made up into cages, they shall be sufficiently rigid to enable them to be handled without damage.

 

8.4      Immediately after the excavation has been completed, the approval of the Engineer’s Representative to commence concreting shall be sought, and when this has been obtained, concreting shall start forthwith and continue without interruption. Unless otherwise agreed by the Engineer’s Representative, no concrete shall be placed in a pile excavation which contains water.

 

8.5      The top of the pile shall be brought above the required cut-off level to allow any defective concrete to be removed, in order to ensure satisfactory bonding of the pile head to the substructure.

 

8.6      When casings and linings are withdrawn as concreting proceeds, a sufficient head of concrete shall be maintained to prevent the entry of ground water or reduction of cross-section of the pile excavation.

 

8.7      No driven cast-in-place pile, or pile case, shall be driven nearer than 5 times its diameter to an unfilled pile excavation, or to an uncased concrete pile, where the concrete has been in place less than 24 hours. Measurement shall be centre to centre.

 

8.8      Excavations for bored cast-in-place piles shall not be exposed to the atmosphere longer than necessary and shall be adequately covered at all times when work is not in progress. The Contractor shall take all the precautions necessary to prevent the ingress of surface water or foreign matter. Lining tubes shall be provided for sufficient depth to ensure the stability of the pile excavation during boring and concreting operations.

 

 

  1. SETTING OUT

 

9.1      The Contractor is responsible for the accurate setting out of the works in accordance with the drawings. All survey stations and setting out points shall be carefully preserved and protected throughout the duration of the work. Damage to them shall be made good to the Engineer’s satisfaction at the Contractor’s expense.

 

 

 

  1. TOLERANCE

 

10.1    All works shall be located to within an accuracy of 75 mm horizontally and to within 1 in 50 of the specified alignment, whether vertically or inclined. Air Products shall be notified immediately if any pile is driven outside the allowable tolerance.

 

10.2    In the event of any pile being driven outside the allowable tolerance, Air Products will undertake an examination, and if necessary, advise on a revised pile layout. Any additional piles resulting from this redesign, plus the cost of the redesign itself, shall be at the Contractor’s expense.

 

10.3    When piles have not been positioned within the limits described, no method of forcible correction shall be permitted.

 

 

  1. TESTING

 

11.1    Load Test

 

11.1.1 The Engineer may order any pile to be tested to not less than 1 1/2 times its working load.

 

11.1.2 The Contractor shall provide kentledge, jacking equipment, or any additional piles as required and all other necessary equipment to satisfactorily test the chosen pile.

 

11.1.3 The pile shall be loaded in 25% increments to the working load, then in 10 t increments to the full test load. The settlement shall be recorded after each increment. Each increment of load must not be added until the settlement has reduced to a rate of less than 0.1 mm in 20 minutes. The full load shall then be maintained for 1 hour, or longer if the rate of settlement should dictate, and then unloaded in increments of 10 t. The rate of rise shall be recorded at each interval, and no further reduction in load shall be made until the rate of rise has reduced to less than 0.1 mm in 20 minutes. Permanent settlement after unloading shall not exceed 7.5 mm.

 

11.1.4 In the opinion of the Engineer, if the pile should fail to carry the load without excess settlement or for any other reason, the Engineer will select a further pile for testing and the Contractor shall carry out the extra test at his own expense. If this pile should fail, further piles will be selected for testing, at the Contractor’s expense, until a satisfactory test has been achieved.

 

11.1.5 Any additional pile or piling required, to support a structure safely due to failure of any tested piles, shall be provided and paid for by the Contractor.

 

11.1.6 Records and graphs of load, settlement, and time of testing shall be made.

 

11.1.7 Two copies of the records of each test signed by the Engineer’s Representative showing typical load, settlement, and time curves, shall be submitted to the Engineer immediately upon completion of the tested pile.

 

11.2    Integrity Testing

 

11.2.1 The Contractor may be instructed to perform pile shaft integrity tests. Such tests shall be performed and interpreted by an experienced person. The Contractor shall prepare the pile heads for the testing apparatus.

 

 

  1. REMOVAL OF PLANT FROM SITE

 

12.1    The Contractor shall not remove pile driving equipment from the site until all pile testing has been completed and has checked the location of each pile.

 

 

 

  1. COMPLETION OF WORK

 

13.1    After completion of piling works and removal of equipment, the site shall be left in a clean and tidy condition including the disposal of all rubbish, waste materials, and surplus soil.

 

 

  1. CUTTING DOWN PILES

 

14.1    This will normally be carried out by others, but if requested by the Engineer or as required in the purchase order, the Contractor shall cut piles down to cut-off levels shown on the drawings, and remove and dispose of excess pile heads. Reinforcement shall be cleaned of all debris and concrete and left projecting upwards.

 

 

  1. DRIVING RECORDS

 

15.1    Records of pile driving shall be kept for each pile as described in the following table:

 

Table 1 – Table of Piling Records

 

Technical Requirements for all Permanent Piling Works

15.2    Duplicate copies signed by the Engineer’s Representative shall be supplied to Air Products daily.

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