SOIL PLUG RESPONSE IN OPEN-ENDED PIPE PILES

The response of the soil plug within driven, open-ended pipe piles is very different under the dynamic conditions of installation and the static conditions of loading during service. This paper addresses the latter aspect and describes a combined experimental and numerical study of the response of soil plugs in open-ended pipe piles. The work focuses on the partially drained (static) loading relevant to offshore applications, and the experimental work is conducted using calcareous sand from Bass Strait, Australia. Model tests are conducted in pipe piles of 25-mm and 100-mm internal diameters, with loading rates as great as 6 MPa/s, using a downward hydraulic gradient to achieve appropriate effective stress profiles in the soil plug. The experimental results are assessed within the framework of analytical solutions of the drained and undrained response of the soil plug and numerical studies of the partially drained problem that allow the results to be extrapolated to prototype conditions. Example applications are given for pile geometries and loading rates typical for Bass Strait.