The p-y model of single pile foundation for OWTs under combined lateral environment loading and earthquake in saturated sand

Abstract

A series of centrifuge tests were conducted on offshore wind turbines (OWTs) subjected to combined static lateral loading and the earthquake (LEAP wave) to obtain p-y curves (where p is the soil resistance and y is relative displacement between pile and soil), and a simplified beam on Winkler foundation (BNWF) model was proposed. The p-y curves are to investigate the influence of static lateral loading on the dynamic pile-soil interaction, and the BNWF model is to verify the p-y curves and to predict the after-shaking horizontal displacement. It's found that the dynamic p-y curve of shallow soil oscillated and moved to the right due to the influence of lateral loading; meanwhile the LEAP wave resulted in liquefaction of the surrounding soil and the p-y curve moved to the lower right, namely, the soil resistance decreased yet the displacement kept increasing. The BNWF model uses a hyperbolic function to fit the experimental p-y curves, and two parameters in the p-y curves, namely, the initial modulus of the subgrade reaction and the ultimate subgrade reaction, were connected with the excess pore pressure ratio (EPR). The comparison between the model and the test results verifies its effectiveness in predicting the after-shaking horizontal displacement.