Development of a new pile driving actuator and a fully instrumented model pile for use in the centrifuge

A new actuator and a fully instrumented model pile have been developed at the Geotechnical Engineering Research Centre at City University to study the behaviour of jacked piles in sands by means of centrifuge testing. The actuator and strong box assembly were designed to operate at up to 200 g. The model pile was instrumented with eleven transducers allowing the base resistance, local shaft resistance and the radial stresses to be monitored continuously during pile installation. The pile has a diameter of 16 mm and is 350 mm long, thus at 200 g represents a prototype pile of 3.2 m diameter and 70 m length. The paper describes the stages of development of both the actuator and the model pile. In addition the process of calibration and the corrections applied to the test data are described in detail. Finally some typical test data are presented and the accuracy of the measurements is discussed.