UBC Theses and Dissertations
Response of pile foundation under simulated earthquake loading Dou, Huaren
An extensive series of small scale model tests on single piles embedded in sand were carried out using the hydraulic gradient similitude (HGS) technique simulating earthquake loading. The dynamic loading was applied using the shake table at the University of British Columbia. The HGS method employs a high hydraulic gradient across the sand sample to increase the effective stresses in the model simulating full scale stress conditions in the field. Since the soil behaviour is stress level dependent, the HGS technique is considered to provide a realistic simulation of the full scale pile foundation behaviour. Free vibration tests were performed to study the natural frequency response of soil-pile system, and the behaviour of the system stiffness and damping at different soil stress levels. The boundary effects are evaluated and discussed. The dynamic behaviour of pile response and soil-pile interaction were investigated over a range of shaking intensities at various exciting frequencies. The dynamic p-y curves were derived from the test data and found to be highly nonlinear and hysteretic at shallow depth. Approximate linear elastic p-y response occurs at greater depth. The test results show an insignificant and negligible influence of loading cycles for dense sand. The backbone p-y curves for sand recommended by the American Petroleum Institute (API) were computed and compared with the experimental data, and were seen to be in poor agreement. The near field hysteretic damping was estimated from the p-y hysteretic loops. The tests create a data base against which the theoretical and numerical approaches can be assessed. Predictions of the response of pile and superstructure to dynamic loading were made using different procedures of constructing p-y curves. The analyses show, generally, a reasonable agreement with test data.
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