Sydney Chapter

Drilled Shaft Instrumentation for O-cell Tests

Haji Fitri Johari

In this talk the general requirements for O-cell instrumentation will be presented, including the differences in instrumentation required for O-cell bi-directional static load tests to conventional load tests, purpose and numbers of various embedded instruments, parameters that need to be measured, instrumentation for additional geotechnical parameters, calculation of plate movements – single level and multi level tests, assessment of the additional elastic compression adjustment required for an O-cell test in comparison to a top-loaded test and the advantages and limitations of single/multi-level O-cell tests.

The added value gained from including strain gauge and extensometer instrumentation will also be discussed. Practical details on the locations and number of strain gauges, assessment of load distribution along the shaft and the use of retrievable gauges in CHSL pipes will be presented together with the importance of actual pile section area, the use of tangent stiffness in the assessment of pile stiffness values and an introduction to the Sonicaliper®.

Methods for the construction of the top-loaded load-displacement behaviour will be presented using the computation methods of summing the measured behaviour or summing the modelled behaviour.

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