The piling contractor shall submit to the consultant the piling forms and formats for approval prior to the commencement of piling works.
Piling contractor shall maintain and provide all the record for each pile driven.
Piling records shall have the following information:
a. Pile Ref. No.
b. Project Name
c. Block d. Pile No.
e. Pile Size
f. Type & Weight of Hammer
g. Ground Level
h. Cut Off Level
i. Total Pile Length
j. Actual Penetration
k. No. of Joints
l. Hammer Drop Height
m. Final Hammer Drop Height
n. No. Of Blows/300mm
o. Final Set per 10 Blows
Handling and Storage of Piles
The piling contractor shall ensure that all piles are stacked correctly with timber being placed right next to the lifting hooks only.
Timber height shall be no less than 75mm.
All piles shall be lifted by using suitable lifting hooks and slings..
Setting out of Pile Points
During setting out by a surveyor, all points must be marked by driving a metal rod no larger than 12.5mm and no shorter than 150mm firmly into the ground.
A brightly colored tape should then be fastened to the end of this metal rod for easy identification.
Pitching and Driving of Piles
Piles can only be pitched by slinging through the lifting hooks.
All piles must be pitched accurately onto the metal rod described previously.
Once the pile has been pitched, its vertically must be checked by means of two plumb lines placed at two different locations before piling can commence.
Its verticality shall be maintained at all times during the driving operation to the entire satisfaction of the client.
At no time shall the center of the hammer be more than 50mm off-center from the axis of the pile being driven.
Piles must be suitably restrained to maintain their position by means of guys or guides, but piles which have been deflected from its course or have been incorrectly aligned, may be forcibly brought back to its correct alignment.
Driving of a pile shall, as far as possible, be in a continuous operation until the required set is obtained.
When driving the initial pile, the hammer drop height shall not be more than 75% of the predetermined hammer height required to achieve set as per Hiley’s Set Formula.
As driving progresses, the hammer height is gradually increased until set is achieved.
During driving, the pile head shall be protected by steel helmet fitting closely around the pile.
A packing of plywood of minimum thickness of 25mm must be placed between the pile head and the steel helmet.
Another packing of plywood or timber stub of thickness 100mm must be placed between the steel helmet and hammer.
The packing shall be renewed as often as necessary to prevent damage to the piles.
The weight, hammer drop height and final set of pile shall be proposed by the piling contractor by means of Hiley’s Set Formula and it shall be strictly observed.
Final Set of Pile
The final set of each pile shall be recorded as the penetration in millimeters per 10 blows.
A set shall only be taken in the presence of consultant/client.
The predetermined final set must be obtained for three consecutive trials of blows each before driving can be stopped.
Basis of Acceptance for Installed Piles
The basis for the acceptance of installed piles is that the driving criteria and final set of a driven pile or the design of any other type of installed pile which has been verified by a successful load test.
Piling contractor shall ensure that all the other piles are strictly driven or installed to the same conditions or better than the initial tested pile which passed the load test requirements, as any further pile chosen for load test which fails to meet the requirement shall be rejected and all costs for remedial piles and amendments to pile caps shall be borne by piling contractor.
The pile sections and details have been designed to safely carry the maximum design load as far as the strength of the pile section itself is concerned and subjected to its proper handling.
Safe bearing capacity of the pile will depend on the driving criteria adopted and the actual soil conditions and shall have to be verified by an initial load test.
Any driving criteria or final set suggested to the contractor shall only be guide and the contractor shall fully satisfy himself as the suitability of the driving conditions and final set.
The piling contractor shall have the right to adopt a different driving and final set, provided that this shall not damage the pile.
For other types of piles or patented piles adopted, the contractor shall be fully responsible in all aspects of the design and installation of the piles.
The acceptance of piles shall be on the same basis as mentioned in above sections.