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Estimation of Pile Head Stiffness Using Analytical
Results of Sonic Integrity Testing
Kazuo Imada, Tatsunori Matsumoto and Masashi
Nakabayashi
ABSTRACT : In this paper, attempts
were made to estimate the initial stiffness of load-displacement curve
of a pile (pile head stiffness) from the signal of the Sonic Integrity
Test (SIT). A series of SIT was conducted on a model pile embedded in
model grounds having different profiles of shear modulus. The wave
matching analyses of the measured SIT signals were conducted using a
computer program based on the one dimensional stress-wave analysis, in
which the influence of the soil resistance is incorporated. The static
load test was then conducted on the model pile to obtain the
load-displacement curve for each model ground. And, the elastic analysis
of the static load test was carried out to estimate the
load-displacement curve for the pile, using the elastic constants of the
ground which have been estimated from the SIT. The calculated
load-displacement curve was close to the measured curve for an early
stage of loading. The procedure for estimating the pile head stiffness
mentioned above was applied to actual cast-in-situ concrete piles on
which the static load test was conducted. The pile head stiffness
estimated from the SIT was comparable with the measured results. This
paper shows that the SIT is applicable to the estimation of the pile
head stiffness as well as the soil modulus, if the wave matching
analysis is conducted taking the influence of the soil resistance into
account. This paper also discussed a variety of application of SIT for
quality assessment of pile foundations.Key words: elastic
modulus of soil, load test, one dimensional stress wave analysis, pole
head stiffness, soil resistance, sonic integrity test (IGC:
E2/E14/H1)
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