High-Fidelity numerical simulation of centrifuge tests on the superstructure-pile-liquefiable sand soil system

This study develops a three-dimensional (3D) cross-scale finite element simulation approach for the entire superstructure-pile-liquefiable sand system, based on the Scaled Boundary Finite Element Method and Finite Element Method (SBFEM-FEM) coupling analysis method for saturated porous media and incorporating a state-dependent generalized plasticity model. A high-fidelity numerical reproduction of centrifuge tests is conducted to validate the approach. First, the sand soil model parameters are calibrated based on existing research. Then, a cross-scale finite element analysis model is established, incorporating Goodman interface elements to simulate pile-soil interaction. The proposed method is validated through comparisons with experimental results, while the spatiotemporal distribution of excess pore water pressure (EPWP) in the soil is further analyzed to assess the effects of sand liquefaction on the pile and superstructure. The key findings are as follows: (1) The proposed method accurately captures the EPWP evolution and dynamic response of structures in sands with different relative densities; (2) A wedge-shaped pile-soil interaction zone exists at the mudline, where the soil first experiences dilation followed by contraction, resulting in significant oscillatory pore pressure. The pile within this zone bears a considerable horizontal load; (3) Three deformation modes of the pile foundation were identified. Liquefaction intensifies pile inclination in loose sand layers while reducing the horizontal displacement of the superstructure. The pile shaft embedded in the dense sand layer reduces the inclination, but the entire shaft embedded in the dense sand layer intensifies the dynamic response of the superstructure.