Research On Seepage Analysis Of Embankment Dam Based On Meshless Local Petrov-Galerkin Method

In the process of seepage analysis of embankment dam,the calculation of the infiltration line is one of the important research contents.In the calculation process,because the location of the saturation line is unknown before,we need to continue iteration to determine the location of the saturation line,so the problem is a moving boundary problem.The finite element method(FEM)needs to be remeshed in the calculation of this kind of problem,which leads to the cumbersome calculation process.The meshless method is not dependent on the grid,and it has a very obvious advantage in dealing with the problem.In this paper,a meshless local Petrov-Galerkin(MLPG)method is adopted.This method is based on sliding Kriging interpolation to construct shape functions,using the Heaviside piecewise function as the weight function,so that shape functions has the property of Kronecker function,and can directly impose essential boundary conditions.only the boundary integral is contained in the derived integral equation,thus reducing the calculation and improving the calculation efficiency.Based on the meshless method,this paper makes a preliminary study on the seepage problem of embankment dam.The main contents of this study are as follows:(1)The theoretical basis of MLPG method is introduced.Based on the idea of iterative method,the method of determining the position of free surface of seepage is put forward,and the calculation program of MLPG method for steady and unsteady seepage flow of embankment dam is compiled with MATLAB.(2)The steady seepage equilibrium equation of embankment dam is deduced by MLPG method based on sliding Kriging interpolation,and the steady seepage field of embankment dam seepage model is simulated.The calculation results are compared with other methods to verify the effectiveness of the method for solving saturated steady seepage problems of two-dimensional embankment dams.(3)The unsteady seepage flow equation of embankment dam is derived by MLPG method based on sliding Kriging interpolation,and the unsteady seepage field of earth rock dam seepage model is simulated.The validity of the method for solving saturated unsteady seepage problems of two-dimensional embankment dams is verified by comparing the calculated results with the experimental results.(4)The influence of different descent velocity on the saturation line in the dam is analyzed.The calculation results show that the pore water pressure in the soil is not easy to dissipate when the water level of the reservoir declines rapidly and the permeability coefficient of the soil is small,and the infiltration line in the dam is seriously lagged during the decline of the reservoir water level,resulting in the unfavorable seepage force on the stability of the dam slope.It is proved that the combination parameters k/(μv) are important for the drawdown index of reservoir water level.Through the study of this paper,the MLPG method is used to calculate the seepage problem of embankment dam,and the validity of the meshless method for the moving-boundary problem is verified.The aim of this paper is to provide a basis for further study of complex moving-boundary problem by using meshless method.