Volume 12, Issue 6

EVALUATION OF PILE TENSION LOADS USING PULL-OUT AND PUSH-OUT METHODS

Author

Anil Cherian

Abstract

Strain gauge instrumented static tension load testing in bored piles can give
the designers a variety of useful information based on the geotechnical
conditions. Traditional tension or uplift tests are performed using the pull-out
method, which is sometimes inappropriate economically and technically. For
the past few decades, Bidirectional Static Load Testing method (BDSLT,
commonly known as the O-cell method) has been proven advantageous over
the conventional pile load testing method for compression piles. However,
the application of BDSLT in tension load tests (push-out), an alternative to
the traditional method (pull-out), is seeking wide acceptance in the
construction industry. This push-out method provides the facility to install
sacrificial jacks within the toe level of the pile and extend an additional
reaction pile below the design toe level. In this article, a comparison of the
upward behavior of the shaft using instrumented pull-out and push-out
methods is studied. The piles of 900mm diameter, 6.0m length were
instrumented with 4 levels of vibrating wire strain gauges and tested up to
5000kN for a high-rise building project in Qatar. The maximum settlement
observed was 4.60 mm for the pull-out test and 4.20 mm for the push-out test,
respectively. The unit shaft friction shows a maximum of 312 kPa for the
pull-out test and 395 kPa for the push-out test, indicating that the outcomes
are fairly similar. The results of this study suggest that push-out tests can be
used as an innovative alternative to conventional technique to bring economic
and project executional benefits.

DOI

https://doi.org/10.62226/ijarst20231134

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