PDCA recently received the following question:
“We have a project in which steel driven piles are implemented.
Pile details are as follows:
•• Pile diameter is 500mm
•• Pile length is 20m
•• Soil conditions are soft to stiff clay till 11m and followed by very
stiff clay to hard clay
The piling contractor installed piles with position tolerance higher
than acceptable. The acceptable position deviation specified for
this project is 75 mm, but a few piles are installed with a maximum
deviation of 200mm (instead of 75mm). However, the piling contractor
tried to rectify the situation by forcibly pushing the pile to its correct
position. In this process, the piles were extracted four to five meters,
pushed to correct position and re-driven.
Are there codes and standards available to address this
issue? Can pile that is forcibly corrected be accepted or not? If it is to
be accepted, what are the tests to be carried out to ensure its integrity
and design capacity?”
In the Federal Highway Administration (FHWA)’s Design and
Construction of Driven Piles manual (which is available for free
online), the specification’s commentary notes that tight tolerances
of three inches (75mm) or less are not practical. Most states post
their specifications online, so individual state approaches to pile
tolerances and remediation of out-of-tolerance piles could be
researched on a state-by-state basis.
Of course, many variables are involved in any specific job site, but
it is not typically allowed to attempt to forcibly push a pile into location
tolerance, even if it is partially extracted first. Generally acceptable
ways to address piles that are out of location tolerance include:
•• Evaluation by the structural engineer. It may be that a
pile being out of tolerance does not result in its design
stresses being exceeded, or the centroid of support of
the pile group being unacceptably relocated, and any
other structural consideration with the pile’s location.
This structural review is often a first step, and if the
findings are positive, it may preclude the requirement for
further remediation.
•• Leave the out-of-tolerance pile in place and drive a
supplemental/replacement pile or piles. This requires a
re-design of the pile cap.
•• Completely extract the out-of-tolerance pile, backfill its
hole with sand or pea gravel and re-drive a pile in the
proper location.
The most-appropriate test that can be performed on an outof
tolerance pile to assess its structural integrity and geotechnical
capacity is likely a dynamic load test; that is, re-striking the
pile while using a Pile Driving Analyzer, and performing subsequent
signal-matching (e.g., CAPWAP) analyses on a representative
blow or two.
Obviously, all of the above potential courses of action have
a cost associated with them, and so in each case it needs to be
determined who pays. Keep in mind that the Owner owns the
ground. If the piles being out of position is the result of subsurface
conditions such as rubble or other obstructions in fill
deposits, cobbles and boulders in fill or native deposits, sloping
bedrock overlain be soft soils, etc., the Owner should pay. If the
piles being out of position is the result of the Contractor’s inappropriate
means and methods, negligence, poor workmanship,
etc., the Contractor should pay. t
jezper/123RF
DID YOU KNOW?
Did You Know?
Driven piles installed out of tolerance:
Can you push the pile into its correct position?
Response compiled from Van E. Komurka, P.E., D.GE, GRL Engineers, Inc. and Dale Biggers, P.E., Boh Bros. Construction Co., LLC
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