Numerical Simulation Of Dynamic Interaction Between Lattice Shaped Diaphragm Wall And Soil

Post-earthquake investigations showed that lateral spreading triggered by liquefaction,as a main cause,has caused severe damage to bridge foundations.Lattice shaped diaphragm wall(LSDW)foundations,as a new type of bridge foundation,provide a new way for this problem.However,the dynamic interaction between LSDWs and soil under earthquake motions is not clear.Therefore,it is of great significance to study this dynamic interaction.On the basis of the results of a dynamic centrifuge test of LSDW foundation in sloping liquefiable deposit,numerical study was carried out to investigate the dynamic interaction between LSDW and soil in depth in this thesis.The main conclusions are as follows:(1)In order to investigate the dynamic interaction between LSDW and soil in sloping liquefiable deposit,a 2D finite element model of the dynamic centrifuge test was established by Open Sees.In this numerical model,the beam-column element based on Euler-Bernoulli beam theory was used to establish the model LDSW,the multiple yield surface plastic constitutive model was used to describe the behavior of saturated sand layer,and the considering liquefaction was put forward to deal with the interface between LDSW and soil.The validity the established 2D finite element model was verified by comparing the numerical results and those of dynamic centrifuge test,in terms of acceleration and pore pressure in the soil core and far field,as well as settlement and horizontal displacement of the LDSW foundation.(2)On the basis of the verified numerical model,the influence of the chamber size,chamber number,slope of the deposit,permeability coefficient of the sand,and amplitudes of earthquake motions on the,dynamic interaction between the LSDW and soil was investigated in numerical studies,in terms of responses of acceleration,excess pore pressure ratio,shear stress-shear strain,foundation displacements,and lateral spreading.The studies show that 1)the amplitude of the input motion influences the dynamic interaction significantly,2)the size and number of chamber govern the development of shear stress and shear strain in the soil core,3)the slope of deposit aggravates the lateral spreading,and 4)the permeability coefficient has great influence on the development of excess pore water pressure.(3)A pile group foundation with the same sectional area as that of the LSDW foundation was established,to compare the different dynamic interactions between foundations and soil in liquefiable deposit under the same earthquake motions.The analysis shows that LSDW under the action of earthquake,foundation inclined and the pile group foundation settled unevenly with bending deflection.Moreover,compared with pile group foundation,the LSDW has stronger resistance to soil liquefaction.