Stability Study Of Unsaturated Red Sandstone Soil Slopes Under Rainfall Condition

There are a large number of unsaturated soil slopes in nature.Due to the infiltration of rainwater in rainy seasons,transient saturation areas are appeared within the slope soil mass,resulted in slope strength decreases.Once the slope is unstable,it will cause casualties and economic losses.In order to obtain the effect of rainfall on the stability of slopes,the red sandstone soil in South of jiangxi was used as the research object,and the remolded soil samples were tested for dewetting and moisture absorption.The initial moisture content and dry density were controlled to obtain the water-soil characteristic curve of red sandstone soil and its fitting equations.The slope stability of rainfall infiltration process was studied by ABAQUS software.The main research contents and results of thesis are as follows:(1)The red sandstone soil samples with different initial moisture content and initial dry density were subjected to a dehumidification and a moisture absorption test by using a pressure plate apparatus,and the soil-water characteristic curves of the soil samples in the dehydration and moisture absorption process were obtained,and the influences of different initial conditions for the curves were analyzed.It can give some rules for reference.(2)An improved exponential function model is proposed.Based on the experimental data,the soil-water characteristic curve equation of red sandstone soil is obtained by fitting.Compared with the F-X model fitting results.The results show that the improved exponential function model fitting effect more better,it shows that the model is more suitable for red sandstone soil.(3)Based on the generalized Darcy's law and the soil-water characteristic curve equation of red sandstone soil,obtained the differential equations of soil moisture in red sandstone,and given the solution of the Galerkin finite element method.(4)Based on the characteristics of soil and water characteristics of red sandstone obtained,the stability of red sandstone soil slope after rainfall and rainfall was analyzed by using ABAQUS software.The results show that rainfall have a greater impact on slope stability.In addition,this paper analyzes the effects of uniform rainfall intensity,rainfall duration and initial rainfall intensity on pore water pressure,saturation and slope safety factor.