Study On Stability Of Unsaturated Soil Slope Under Rainfall Condition Based On Xingye District

Rainfall infiltration is an important factor to induce the instability of unsaturated soil slope.In order to study the evolution law of unsaturated soil slope stability under rainfall conditions,this paper takes Xingye County of Guangxi as the research area,summarizes the distribution law and development characteristics of landslide geological disasters in Xingye County of Guangxi,the soil water characteristic curve of granite residual slope soil is studied through pressure plate test.Based on the theory of seepage,shear strength and seepage stress coupling of unsaturated soil,and Geo-Studio 2018 On the platform of finite element numerical analysis software,the numerical simulation analysis of artificial slope of granite eluvial soil under different rainfall conditions is carried out.On this basis,the evolution laws of seepage field,stress field,deformation field,slip surface and stability of the slope are studied,and the mechanism of rainfall induced slip slope is discussed.Finally,the application of the landslide in Yulin national middle school is carried out.The main research results are as follows:1.The landslides in Xingye county are mainly soil and small-scale landslides.The shallow landslides with a thickness of less than 5m are mainly distributed in granite area.Rainfall is the main factor inducing landslides in Xingye county.The probability of landslides in rainy season is high,and the density of landslides in areas with intensive artificial slope cutting is high.2.Through the pressure plate test,the soil water characteristic curve of the dehumidification process of granite residual slope soil is obtained,and the influence of different initial water content on the soil water characteristic curve is studied.The results show that the soil water characteristic curve of the sample with small initial water content is located under the sample with large water content,which has the characteristics of fast dehydration speed and low water holding capacity.The V-G model is better for fitting the soil water characteristic curve of granite residual slope soil.3.The results of numerical simulation under four rainfall conditions show that: after rainfall,the shallow soil of the artificial slope responds first,and the response of the soil inside the slope is slow or not affected by rainfall.With the increase of rainfall duration or rainfall intensity,the depth of rainwater infiltration is deepening and the affected area is expanding.Influenced by rainfall infiltration,the pore water pressure,volume water content,maximum shear stress,maximum shear strain and displacement of soil mass are positively related to rainfall duration and rainfall intensity,while the slope stability is negatively related to rainfall duration and rainfall intensity Department.The effect of increasing rainfall on pore water pressure and volume water content of shallow soil mass is different from that of average rainfall,single peak rainfall and decreasing rainfall.The plastic deformation area caused by short-term heavy rainfall coincides with the position of the most dangerous slip surface.4.In the natural environment,most of the slopes are in the unsaturated state,and the rainfall infiltration process is essentially a gradual process from the unsaturated state to the local saturated state.For the unsaturated area,the increase of pore water pressure and volume water content causes the decrease of matrix suction and effective force,resulting in the deformation of the slope,weakening the shear strength of the soil.It has an adverse effect on the stability of the slope.