Centrifuge Test And Numerical Simulation Analysis Of Pile-Soil-Structure System Of High Pile Wharf In Liquefaction-Induced Lateral Spreading Ground

High-pile wharf has been widely used in China ’ s port engineering due to its simple structure,large load,good wave attenuation effect,and suitable for soft soil foundation widely distributed in coastal areas.However,in the past destructive earthquakes,due to the engineering geological conditions in the coastal port area,it is prone to liquefaction-induced lateral spreading,resulting in a large number of high-pile wharf damage.Therefore,the seismic research of pile foundation in liquefaction-induced lateral spreading ground has become a key problem in geotechnical seismic field.For the purpose of improve the seismic capacity of buildings in China and reduce the seismic loss,it is necessary to study the problem in depth.In this paper,the dynamic response and load transfer law of the high-pile wharf in the liquefaction-induced lateral spreading ground are studied by using the centrifugal model test and finite element analysis of single pile foundation.The main work is as follows :（1）Centrifugal model test of pile-soil-structure system of high-pile wharf in liquefactioninduced lateral spreading ground.Based on the seismic damage records of high-pile wharf pile foundation at domestic and abroad and the previous model test data,a 1 : 5 slope was set in the site to trigger the liquefaction-induced lateral spreading.The centrifugal model test of pilesoil-structure system in a 1 / 50 scale liquefaction side expansion site was successfully carried out.The test results of free field pore pressure,acceleration,pile bending moment and soil displacement were analyzed.It is found that with the gradual liquefaction of the loose sand layer,the clay layer moves to the sea side together and a large lateral displacement occurs,and the maximum bending moment of the pile body appears at the interface of the soil layer.It is suggested that the bending capacity of the pile foundation in the seismic design of high-pile wharf should be focused on.（2）Numerical simulation analysis of pile-soil-structure system of high-pile wharf in liquefaction-induced lateral spreading ground.On the basis of the centrifugal model test of pile-soil-structure system,the two-dimensional numerical analysis model of pile-soil-structure system in the liquefaction-induced lateral spreading ground was established by using Gid and Open Sees finite element software.In modeling,the selection of saturated soil constitutive model and soil element is considered first,and the simulation method of free water body,the simulation of pile foundation and superstructure,the setting of boundary conditions and the calculation steps are introduced.In the model,the pile foundation adopts elastic beam-column element and connects the pile foundation and soil element with p-y spring;when setting the boundary conditions,the free field boundary is selected to reduce the influence of wave reflection.Secondly,the response cloud chart of gravity analysis is drawn to ensure the accuracy of the initial state of the model.Finally,the reliability of the two-dimensional numerical model is verified by comparing the dynamic analysis results with the centrifugal model test results.（3）Study on load transfer law of single pile foundation of high-pile wharf in liquefactioninduced lateral spreading ground.For the load transfer behavior of pile-soil-structure system of high-pile wharf,the relationship among soil displacement,inertial load and motion load is mainly considered.Firstly,the mechanical analysis of the pile-soil-structure system of highpile wharf is carried out,and the motion load acting on the pile is obtained by the inverse calculation of the total shear force and inertial load of the pile.Based on the finite element simulation results of the pile-soil-structure system of the high-pile wharf in the liquefactioninduced lateral spreading ground,the corresponding conditions of the pile displacement,the total shear force of the pile,the peak inertial load and the peak motion load are analyzed.In addition,based on the established finite element model,the influence of superstructure mass,pile stiffness and clay strength on the combination of inertial load and motion load is analyzed.