Numerical modeling and simulation of pile in liquefiable soil

Abstract

Presented in this paper is numerical methodology to model and simulate behavior of piles in liquefiable soils. Modeling relies on use of validated elasto-plastic material model for soil skeleton, verified fully coupled porous media (soil skeleton) – pore fluid (water) dynamic finite element formulation, and detailed load staging of FEM models. A bounding surface elastic–plastic sand model that accounts for fabric change is used to model soil skeleton, while a fully coupled, dynamic, inelastic formulation ( u – p – U ) is used to model soil and water displacement and pore water pressures. Much attention is paid to accurate staged loading of the models, which start from a zero state of stress and strain for a soil without a pile, followed by application of self-weight, then by excavation and pile installation with application of pile self-weighting. Finally, seismic loading is applied followed by time to dissipate excess pore pressures that have developed. A total of six cases were modeled and simulated varying slope inclination, presence of pile–column and boundary condition for pile–column system. Presented are interesting and useful results that are used to deepen our understanding of behavior of soil–pile–column systems during liquefaction (lateral deformations, pile pinning effect, ground settlement). Moreover, detailed description of modeling is used to emphasize the availability and use of high fidelity modeling tools for simulating effects of liquefied soil on soil–structure systems.