Geotechnical News • September 2016
19
GEOTECHNICAL INSTRUMENTATION NEWS
Bored piles (drilled shafts)
General role of instrumentation
Many uncertainties exist during
design of bored piles (also called
drilled shafts), and instrumentation
plays a role in determining the load-
movement relationship, by conduct-
ing load tests. Concrete integrity is
often uncertain during construction,
particularly when they are constructed
in granular soils below the water
table or in softer, squeezing clays,
when concrete slump is inadequate,
or when concrete placement practices
are inferior. Instrumentation can be
used to examine the integrity of the
concrete. For piles cast under support
fluid, concrete integrity at the pile tip
is particularly important.
Summary of instruments that can
be considered for helping to provide
answers to possible geotechnical
questions
Table 9 lists the possible geotechni-
cal questions that may lead to the use
of instrumentation for bored piles,
together with possible instruments
that can be considered for helping to
provide answers to those questions.
Table 9. Some instruments that can be considered for monitoring bored piles
Possible geotechnical questions
Measurement
Some instruments that can be considered
What is the load-movement relationship of the
pile?
As in Table 8
Load at toe or in pile
As in Table 8
Osterberg load cell
What is the integrity of the concrete?
Condition of pile
Integrity testing
