Piling Work Specification

Piling Work Precast Concrete Piles A.

GENERAL

Precast Concrete Piles shall be obtainable from approved Suppliers/manufacturers. All concrete piles used shall be precast concrete piles and shall generally with British Standard Code of Practice CP 2004 : 1972 “Foundations” unless specified in this section of the preambles. B.

PILE SIZES AND DESIGN

The respective working load and dimensions of the piles are set out in the Engineer’s Drawings or as directed by the Engineer. C.

PRECAST CONCRETE DESIGN

The precast concrete piles shall be square section and manufactured under factory controlled conditions by an approved manufacturer. The piles shall be designed to conform with the relevant British Standard. The grade of concrete shall be Grade 45 (45 N/mm2) and the main reinforcing bars shall consists of high tensile deformed bars to conform to B.S. 4449. All starter piles shall be complete with a flat steel plate fitted at the toe and a female jointing plate for pile extension at the other end. Where piles are required to penetrate rock, cast iron shoes or rock shoes shall be fitted at the toe. D.

CONCRETE

Aggregate: Coarse aggregate shall be crushed granite not containing any deleterious material, mud, salts, organic matter of excessive fine. The maximum nominal size of the coarse aggregate shall not exceed 30mm or 2/5 the wall thickness of the pile whichever is less. Fine aggregates shall be clean river sand or washed mining sand passing B.S. sieve No.7. Cement: Cement shall be ordinary Portland cement to B.S. 12.

Water: Water used for producing concrete shall be free of oil, acid, salts, organic matter or anything that may produce harmful reactions with the cement or steel. In particular it shall not contain any chloride or nitrate ions. Admixtures: Admixtures may be used provided they shall not contain any chloride or nitrate ions. A.

LIFTING POINTS

No special lifting bolt or wire rope is cast into P.C. piles. Lifting is been wrapping wire rope round the piles at specific points. B.

WELDING

All welding shall be carried out in accordance with the requirements of B.S. 5135:1974 –Metal-Arc Welding of carbon and carbon-manganese Steel. The Contractor shall supply the S.O. with full details of his proposed method of welding and shall, if required, arrange for a demonstration. The Contractor shall employ not less than two teams of welders. C.

TESTS FOR APPROVAL OF WELDERS

The Contractor shall arrange for his welders to be qualified in accordance with the requirements of AWS Code D1.1. Only welders who pass the qualifying tests for the type of weld specified shall be employed on the Works. D.

EXAMINATION OF WELDS

One hundred percent of the fillet welds shall be tested using magnetic particle or dye penetration test methods. Copies of these tests records and reports shall be furnished to the S.O. The cost of these tests and reports shall be borne by the Contractor. Where such examination reveals defects in the welds, the joints will either be rejected or the Contractor will be permitted to carry out repairs to the weld and will be retested as specified above and required to submit at is expense. If the repeat tests show the weld to be still defective, the joint shall be rejected. The defective weld shall be removed, replaced with a fresh weld and re-examined. For the purpose of this Clause, cracks, leaks, laminations, lack of complete fusion, undercutting or reduction in wall thickness adjacent to the weld shall constitute a defect be permitted for a pile.

A.

TRIAL PILES

The Contractor shall as soon as practicable after the acceptance of his tender, drive and test trial piles either singly or in groups in permanent position as directed by the S.O. The trial pile shall be in conformity with the requirements of the relevant clauses in the Specification. If the pile is required to be extend, the Contractor shall joint an extension pile as shown to the length as directed by the S.O. After joining, the extension pile shall be driven to the site required and further load test shall be carried out. The Contractor’s attention is particularly drawn to the fact that he will not be eligible for any extra payment for loss of time for labour or idling plant etc. during this period. Where positions of test piles are not shown on drawing, they shall be decided by the S.O. on site. B.

HANDLING

Piles shall be carefully handled and lifted in strictly accordance to manufacturer’s requirement and shall not be jolted or stacked in a manner which will subject them to bending. All piles damaged during handling, driving on at any other times shall be replaced at the Contractor’s expense. A.

PITCHING AND DRIVING VERTICAL PILES

Piles shall be pitched accurately in the positions and driven to the appropriate lines and levels shown on the Drawings. Piles may be suitable constrained to maintain their correct position by means of guys or guides but no pile which has been deflected from its course, or has been wrongly aligned shall be forcibly brought back to correct alignment. Where piles are driven below the level of the bottom of the leads of the pile frame, extension lead shall be fitted. The use of a follower will not be permitted except with the written approval of the S.O. During driving the heads of the piles shall be protected by a helmet of cast steel or mild steel fitting closely around the pile. A packing of coiled hemp or asbestos fibre, 1” thick, covering the head of the pile, shall be contained within the helmet and separate the helmet from the head of the pile. The top of the helmet shall be recessed and fitted with a timber stub folly 1 foot long. The packing and stub dolly shall be renewed as often as necessary to revent damage to the piles. The type of helmet specified above may be modified at the discretion of the S.O. The Contractor shall maintain a record of the driving of all piles giving sets and other data required by the Superintending officer to whom the records shall be submitted on request. All piles shall be driven to the depth shown on the Drawings or to such final

set or depth as may be approved by the S.O. Immediately after a pile has been completely driven a record shall be made of he reduced level of the pile head and further checks shall be made on the level of the head after the driving of adjacent piles. Should any pile heave upwards it shall be re-driven to its original level or, if necessary, until its specified set is again obtained. B.

PLANT FOR PILE DRIVING

The plant used for pile driving shall be such type and capacity as meets the approval of the S.O. A.

LOAD TEST

Soon after the driving of the test piles and before the bulk of the piles are cast, the Contractor shall arrange to carry out a load test on one of these piles and such further test loading as the S.O may order. The test load shall be applied in an approved manner and in stages so that observations of the settlement can be recorded at different increments of load. The test load shall be two times the design load as indicated on the Drawing. The applied load shall be maintained for such periods as the S.O. may direct. An increment in load shall not be applied until all movement of the pile under the previous load has ceased. When the maximum test load is reached, this shall be maintained for a minimum period if 24 hours after all movements have ceased. The loads shall be removed in stages as directed as directed by the S.O. and the recovery of the pile settlement, if any, shall be recorded at each stage. On completion of the load test, the S.O. will instruct the Contractor on the lengths of piles to be cast and the set to which the remainder of the piles are to be driven. During the course of the driving the rest of the piles, the S.O. will select further piles for load test and the Contractor shall carry out the test as above described. The residual settlement of the piles under full test load shall not exceed ¼”. If the settlement of any pile exceeds the specified limit, the contractor shall carry out three further tests on piles selected by the S.O. for each failure and the cost of carrying out these additional tests shall be borne by the Contractor. B.

DEFECTIVE PILES

The method used in driving piles shall not subject them to excessive and undue abuse producing crushing and spalling on concrete. Manipulation of piles to force them into proper position, if considered by the S.O. to be excessive, will be permitted. Any pile damaged in driving by reason of internal defects, or by improper driving, or driven out of its proper location in excess of the allowable tolerance, or driven below the elevation fixed by the Drawings or by the S.O. shall be corrected by the Contractor without added compensation of one of the following methods approved by the S.O. for the pile in question:

1) The pile shall be withdrawn and replaced by a new and, when necessary, longer pile. 2) A second pile shall be driven adjacent to the defective pile. As required by design consideration to be determined by the S.O., all additional work necessary shall be carried out, including provision of a third pile and any alteration to pile caps. 3) The pile shall be spliced or built up as otherwise provided herein or a sufficient portion of the footing extends to properly embed the pile. All piles pushed up by the driving of adjacent piles or by any other cause shall be driven down again. A pile will be considered defective if it has a visible crack, or cracks, extending around the entire periphery of the pile or through the wall or the pile, or any defect which, as determined by the S.O., affects the strength or life of the pile. A.

CUTTING OFF AND CAPPING PILES

Tops of foundation piles shall be embedded in the concrete footing or pile cap, a minimum depth of 150mm (measured at centre line of pile) unless otherwise shown on the Drawings. Piles shall be cut off level or as shown on the drawings, at the elevation indicated on the Drawings. The length of pile cut-off shall be sufficient to permit the removal of all damaged material. The distance from the side of any pile the nearest edge of the footing shall be as shown on the Drawings. Then the top elevation of pile is below the elevation of the bottom of the cap, the pile, shall, if approved by the S.O. be built up from the butt of the pile to the elevation of the bottom of the cap by approved method. The cuts shall be made accurately in clean, straight lines; care shall be exercised to avoid damaging the remaining pile and to ensure full bearing between the footings (or caps) and piles. The piles cut-off lengths, if not required by the S.O., shall be dispose by the Contractor from the Site at the Contractor’s expense. The Contractor shall submit to the S.O. for approval his proposed method of cutting off piles. Piles shall be driven in accordance with the specified criteria and as ordered by the S.O., and shall not overdriven to avoid cutting off, without the approval of the S.O. The cast-in-place non-shrink concrete cap shall not be poured until the inside of the precast pile has been inspected by the S.O. and his approval is obtained.

A.

UNIT RATES

The pay length for delivery, transport, and supply of the piles shall be the length between the toes of pile to existing platform level. The pay length for driven shall be measured from the length between the toes of pile to existing platform level. The rate for cutting off pile hall include for carting away the surplus length from site. B.

PILES OUT OF ALIGNMENT

A maximum deviation of 3in. (75mm) from the location as shown on the drawings shall be permitted. The maximum deviation from the vertical shall not exceed 1.3 percent on any section of the length. The cut-off level shall be within 1in. (25mm) to that shown on the drawing. Piles not meeting these tolerances will be rejected and corrective measures shall be approved by the S.O. If any one rejected pile requires one or more replacement piles only one pile shall be measured for payment. The extra cost for modifying the sub-structure works shall be borne by the Contractor if in the opinion of the S.O. such variation has been occasioned by the in-competency and/or negligence of the Contractor.