Response analysis of single pile embedded in saturated sand under bidirectional cyclic loading

Abstract

In this study, the dynamic responses of a single pile in liquefiable sand under bidirectional loading are investigated using fully coupled three-dimensional nonlinear finite element analyses. A multi-surface plasticity model is adopted to simulate the liquefiable sand behaviour. The analysis procedures elaborate the bidirectional shaking patterns of 2-D linear, circular, and oval shape simultaneously. Results reveal that compared to the unidirectional loading, the bidirectional loading reduces the soil liquefaction resistance and increases the depth of liquefied soil layer. The results also showed that the phase difference between orthogonal components of base excitation and the frequency content of the input motion have a significant impact on the dynamic responses of soil and pile. In addition, an increase in the phase difference reduces the excess pore water pressure and the thickness of liquefied layer, and delays the liquefaction occurrence. Moreover, the maximum pile bending moment and its location correspond to the dominance of either inertia or kinematic interaction forces, which are primarily influenced by the frequency content of input motion.