Numerical modeling of pile embedded in crushable sand subjected to earthquake loading

The response of a pile embedded in crushable sand subjected to earthquake loading is studied using finite elements. For this purpose, a bounding surface plasticity soil model (SANISAND08) is enhanced to incorporate the grain breakage via the evolution in the critical state line. The adaptive Runge–Kutta–Fehlberg stress integration method is adopted for the numerical implementation of the constitutive model. The model is implemented onto the finite element program as user-defined material. The predictive ability of the enhanced model is examined against the laboratory tests, while the pile response is validated based on the simulation results available in the literature. The effect of particle breakage on the pore water pressure ratio development and consequent changes in bending moment, pile skin friction, and pile settlement is assessed under different earthquake loading scenarios. Simulation results show that particle crushing primarily occurs at the initial stages of seismic excitation, and it escalates pore water pressure, leading to liquefaction susceptibility near the pile. Such a rise in pore water pressure considerably increases pile bending moment and reduces skin friction resistance.