The Study On The Application Of Element-free Galerkin Method In Large Liquefaction Deformation

Sand liquefaction is one of the important forms of earthquake disasters,and the large deformation caused by sand liquefaction in earthquake is also widespread for the past few years.The damage caused by large deformation to the underground pipelines,roads,buildings and other lifelines engineering in the liquefied area is more serious than that of the simple sand liquefaction.At present,the finite element method is the most frequently used method among numerical simulation methods on geotechnical engineering problems.However,when the finite element method is used to make the dynamic analysis of large liquefaction deformation of saturated sand,it is found that calculating interruption will appear due to the local unit distortion of the soil mass in the case of large inhomogeneous deformation.Different from the finite element method,which needs to construct approximating function through unit connection,the meshless method needs to construct approximating function just through a set of discrete nodes.These nodes are independent of each other and they are not constrained by units or grids.Thus,this method can overcome the calculating interruption caused by unit distortion,and it is very suitable for the numerical analysis under the condition of large deformation.In this thesis,the application of the Element-free Galerkin method in the large deformation of saturated sand liquefaction is mainly studied in three aspects:1.The Element-free Galerkin method is applied to numerical simulation of large liquefaction deformation of saturated sand,and the calculation results will be compared with that calculated by the finite element method.The pile-soil model verifies the validity of Element-free Galerkin method in the analysis of large liquefaction deformation.When the finite element method is emp loyed to make an analysis of the pile-soil model in the condition of the large deformation,the calculating interruption will appear due to the local unit distortionduring calculation.However,the Element-free Galerkin method can avoid this phenomenen,which shows the superiority of the Element-free Galerkin method in the simulation of large liquefaction deformation.Meanwhile,the comparasion of the calculation results of the two methods before the interruption verifies that the Element-free Galerkin method is effective.2.The Element-free Galerkin method is adopted to analyze the given slope model.Firstly,the Element-free Galerkin method and the finite element method are used for calculation at the same time.It finds that when the seismic wave is input,the application of the finite element method can't make the calculation performed due to the local unit distortion of the slope toe caused by the large liquefaction deformation of saturated sand.But the Element-free Galerkin method can be used to complete the calculation.Hence,the Element-free Galerkin method is employed to analyze some factors of the slope model,like the permeability coefficient,initial modulus ratio,ground motion direction,slope,various soil mass,etc.3.Based on the above conclusions and the summary of other literatures,the prevention and control measures of large ground deformation induced by earthquake liquefaction are summarized briefly.