Cyclic Lateral Load Testing of Model Pile Segments in Sand: Equipment Development and Early Results

The growing offshore wind energy sector has led to renewed interest in the design performance of pile foundations under cyclic lateral loading. Under service conditions, the lateral pile-soil reaction at small deflections and its evolution under many load cycles is of significance. Loading from occasional extreme storm events adds further complexity. In the long term, cyclic loading could cause changes in stiffness and lead to progressive tilting of the pile. To improve our understanding of the underlying mechanisms that may occur in the pile-soil system, an apparatus for model pile-segment testing has been developed at the University of Oxford. The apparatus provides a controlled environment for pile-segment loading tests and is capable of simulating field-level stresses, strains, and drainage conditions. The system can apply large numbers of cycles, at varying frequencies and amplitudes, and permits measurement of soil reaction at the soil-pile interface. The development of the new apparatus and preliminary test results are presented herein.