| Rainfall infiltration is one of the main inducing factors of landslides,and the ways in which infiltration affects the stability of different types of landslides are different.Fuliyuan landslide is located in the southern foothills of the Himalayas,one of the largest rainfall areas in China.75% of the annual rainfall in the area is concentrated in the rainy season.The silty clay layer is developed,and the upper layer is extremely rich in water retention.In order to study the effect of rainfall infiltration on the seepage and stability of the accumulation layer landslide,this paper first analyzed the material structure and hydrogeological conditions of the Fuliyuan landslide,and then based on the unsaturated seepage theory,the finite element of the seepage field of the landslide during the rainfall process was analyzed.Simulation,and finally combined with saturated-unsaturated soil mechanics theory,analyzed the variation of the stability of sliding bodies at different depths during the rainy season.The main contents of the study include:(1)According to the data of rock and soil mass and water inflow during the excavation of anti slide pile,it is concluded that the groundwater distribution of landslide is mainly controlled by the permeability and topography of rock and soil mass,and the runoff path of groundwater is speculated.(2)According to the material composition and structure characteristics of the landslide and the hydrogeological condition characteristics of the landslide,the hydrogeological structure of the welfare institute is analyzed.The upper layer of the landslide is rich in stagnant water.There are several relative aquifers in the vertical and horizontal direction,and there is no unified groundwater level.The seepage system of each grade of landslide is relatively independent.(3)Combined with the material composition and structural characteristics of landslide,the paper analyzes the mode of rainfall induced landslide action,including the influence of the increase of soil moisture content on the strength parameters(C,?value)of sliding body and sliding belt,and the influence of the increase of static and dynamic water pressure on the suction of unsaturated soil matrix and the mechanical action of sliding body.(4)The main section of the landslide is selected to simulate the seepage field during the rainy season.The parameters of transient pore water pressure and matrix suction at each sliding surface in seepage field simulation are extracted,and the influence of stability of landslide is evaluated by combining with shear strength theory of saturated unsaturated soil.The settlement results show that the landslide stability is mainly affected by rainfall intensity,total rainfall and the hydrogeological structure of the landslide mass.The specific performance is as follows: 1.Due to the water isolation of low permeability rock and soil mass,the seepage in the shallow soil mass of the landslide is blocked,the supply of rainwater to the deep part of the landslide is weak,and the deformation and instability of the landslide mainly occur in the shallow surface of the accumulation body;2.The initial rainfall The quantity has a greater influence on the stability coefficient of landslide mass;3.The limit rainfall that causes landslide instability is controlled by the daily average rainfall intensity.The larger the rainfall intensity is,the shorter the time for the landslide mass to reach the limit equilibrium state is,the smaller the limit rainfall is required. |
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