Unsaturated Infiltration Model And Slope Stability Analysis Based On Soil Hydraulic Characteristics

As one of the most widely distributed and most serious geological disasters in China and even in the world,landslide disaster seriously threatens the safety of human life and property and has great destructive power to the natural environment.The occurrence of landslide is affected by many factors,and the most important one is rainfall infiltration.The rainwater leads to the increase of soil moisture content,bulk density and sliding force.The matrix suction of soil decreases with the rainfall,which reduces the shear strength of soil,destroys the original state of stress balance and finally leads to the occurrence of landslide disaster.Therefore,it is necessary to study the movement of soil water and the influence of rainwater on landslide under the condition of rainfall infiltration,so as to provide theoretical basis and application value for the early warning and prevention of rainfall landslide.Therefore,on the basis of previous studies,based on the hydraulic characteristics of soil,this paper studies the water movement of unsaturated soil,and then analyzes the dynamic changes of shallow slope stability in the process of rainfall infiltration with the limit equilibrium analysis method.The main research contents and achievements are as follows:First of all,based on HYDRUS-1D software,the water movement process of different texture soil under the condition of ponding and rainfall infiltration is simulated,and the distribution of the section volume moisture content in the wetted area of different texture soil is analyzed.It is found that the section volume moisture content in the wetted area is not fully saturated,especially for clay and silt quantity changes continuously along the depth direction.Secondly,considering the unsaturated hydraulic characteristics of the soil,the flow saturation function F(?)and the linear simplification of matrix suction in the wet area are introduced to derive two kinds of infiltration models suitable for different texture soil.The results are compared with the measured data,HYDRUS-1D simulation results and the traditional Green-Ampt model.Then,based on the whole process of rainfall infiltration,considering the case that rainfall intensity is greater than or less than the saturated permeability coefficient of soil,the traditional Mein-Larson model is improved,and two rainfall infiltration models suitable for different texture soil are derived.Compared with the simulation results of HYDRUS-1D and the traditional rain infiltration model of Mein-Larson.Finally,considering the influence of inclination angle on rainfall infiltration,the approximate solution of one-dimensional slope rainfall infiltration based on the whole rainfall process and the slope rainfall infiltration model based on linear simplification of matrix suction are derived.The Seep/W module of Geo Studio software is used to simulate the unsaturated seepage of the hypothetical slope case.By comparing with the numerical solution and the traditional Mein-Larson rainfall model,the rationality and correctness of the rainfall infiltration model in this paper are verified.Based on the rainfall infiltration model of slope,the dynamic analysis method of shallow slope stability under rainfall infiltration condition is derived with the wet front as the potential sliding surface.On the basis of Seep/W module seepage simulation,the stability of the hypothetical slope case is calculated by using the Solpe/W module.By comparing with the numerical solution and the stability coefficient change rule calculated by the traditional Mein-Larson model,the feasibility of the stability analysis method of the shallow slope under the condition of rainfall infiltration in this paper is proved.