3D Nonlinear Analysis Of Pile-Soil Interaction In Lateral Spreading Of Liquefied Ground

During strong earthquake,liquefied ground under gravity frequently has horizontally spreading deformation which is usually large and permanent.As a main type of seismic damage,it causes serious damage of highways,railways,bridges,docks,embankments, buildings,underground structures and lifeline engineerings in liquefied area.However,the damage of piles induced by lateral spreading of liquefied ground is more serious.Therefore, the influence of ground flow on pile-soil interaction and piles' internal force and deformation, is always the hot spots in geotechnical engineering.Based on Biot's dynamic consolidation theory for two-phase mixture,the seismic response analysis for the pile-soil interaction in the lateral spreading with different velocities is simulated by a FE-FD coupled method.In numerical analysis,u-p formation of dynamic consolidation equation and cyclic elasto-plastic constitutive model are used.Using updated Lagrangian method,large deformation of liquefied ground is considered.Simulating the process of shaking test,mechanism of pile-soil interaction in liquefied and laterally spreading is studied.The main work is as follows:(1) Using simplified three-dimensional model of single pile,the interaction between single-pile and soil is simulated.By calculating the situations in different velocities,the behavior of liquefied and laterally spreading ground on internal force and deformation are obtained.The effects of inclination on pile's internal force and displacement are also discussed.(2) The three-dimensional model of free soil under the same loading condition of single-pile model is also analyzed.The deformations of pile and free soil are compared in order to get the relative displacement of pile against free soil.The laws of the relative displacement on distribution of pile's internal force are studied.(3) Using simplified three-dimensional model of four piles,the interaction between four piles and soil is simulated.The effects of liquefied and laterally spreading ground on piles' internal force and deformation are discussed.The difference of internal force and deformation between front piles and behind piles is analyzed.Comparing the results,it is obtained how the internal force and displacement of piles varies with velocities.