Pile Design and Construction Practice, Fifth edition

514 Ground investigations, contracts and pile testing
Piling records. The Engineer and the Contractor should agree to the form in which
records should be submitted (see Section 11.3).
Cutting down pile heads. The specification should define whether it is the main contractor’s
or the piling contractor’s responsibility to remove excess lengths of pile projecting above the
nominal cut-off level. The responsibility for cutting away concrete to expose reinforcement,
and trimming and preparing the heads of steel piles should also be stated.
Method of measurement. The method of measuring pile lengths as installed should be
based on an appropriate standard, for example, as given in Civil Engineering Standard
Method of Measurement (11.17) or in the ICE Specification, modified as necessary to meet
particular contract circumstances, structures and sites. Care is needed to define the length
of pile to be measured (i.e. from cut-off level to pile toe or ground level to toe) and to state
that it is the total length of a particular type and diameter of pile is to be measured. Credits
for short piles installed and extra payment for additional lengths of individual piles are
generally excluded from the standard methods.
Removal of spoil. The respective responsibilities for the removal of spoil from bored piles,
the removal of cut-off lengths of pile, trimming off laitance and ground raised by ground
heave, and the disposal of used bentonite slurry should be covered in the specification and conform
with the statutory regulations for waste disposal currently in force (see Section 11.2.1).
11.3 Control of pile installation
11.3.1 Driven piles
Control of driven pile operations commences with the inspection and testing of the
prefabricated piles before they are driven. Thus timber piles should be inspected for quality,
straightness and the application of preservative. The operations of casting precast concrete
piles on site or in the factory should be inspected regularly and cubes or cylinders of the
concrete should be made daily for compression testing at the appropriate age. Materials used
for concrete production should be tested for compliance with the relevant standards. In the
case of steel piles, tests should be made for dimensional tolerances and full documentation
of the quality of the steel in the form of manufacturers’ test certificates should be supplied
with each consignment. Welding tests should be made for piles fabricated in the factory or
on site. Full radiographic inspection of welds may be necessary only for marine piles, where
the exposure conditions are severe (see Section 10.4.2). The coating treatments should be
checked for film thickness, continuity, and adhesion. Degaussing may be needed to counter
magnetization of the pile heads caused by driving. This can be detrimental to the quality of
welds made for pile extensions. BS EN 288 covers degaussing steel by generating a counteractive
magnetic field when welding is in progress.
The ICE Specification lists the information which should be recorded for each type of
pile; Table 11.2 is a typical compliant form. A separate record should be provided for each
pile and records should be signed by the Contractor’s and Employer’s representatives and
submitted daily. Records to comply with EC7, Clause 7.9, are similar to Table 11.2, but
should be provided in two parts according to BS EN 12699 for each displacement pile driven.
Part 1 should give general information on the contract and type of pile, methods and quality
of materials; Part 2 ‘particular information’ as tabulated in Clause 10 of this standard for
each pile. ‘As built’ records of piles have to be submitted to the Employer. It is advisable to
keep all records for a period of 5 years after completing the works.