Stability Analysis Of High Liquid Limit Residual Soil Slope In Strongly Weathered Granite Area

The Granite residual soil is widely distributed in Hunan,China.Its engineering properties are poor,the water intensity is drastically reduced,and it is easy to soften and collapse.Under the influence of humid and rainy climate in Hunan,granite residual soil slope often suffers from dehumidification,humidification and dry and wet alternates.The cyclical effect is prone to common geological disasters such as shallow soil slippage,disintegration,and water damage,which seriously threaten people's lives and cause huge economic losses.Focusing on the protection of engineering geological disasters and the need of engineering construction,this paper takes the granite residual soil as the research object,carries out the test of the soil residual water characteristic curve of granite,the shear strength test under different dry density and saturation,and deeply analyzes it.The variation of shear strength of granite residual soil,and the variation law of granite residual soil slope under rainfall infiltration effect is simulated by ABAQUS finite element analysis software.The instability induced factors of granite residual soil slope are summarized.Practical analysis method for stability of granite residual soil slope.The main research contents of this paper are as follows:(1)Conducting indoor geotechnical test of granite residual soil,and determining the basic physical property parameters of the soil sample: initial density,initial water content,liquid limit,plastic limit,maximum dry density,optimum water content,specific gravity,soil particle composition index Curvature coefficient and uneven coefficient of soil particle composition index.according to the engineering classification standard of soil in the geotechnical test procedure,it is determined that the granite residual soil is a graded bad soil.(2)The soil water characteristic curve test is carried out on the granite residual soil.The test results show that the granite residual soil increases with the increasing suction capacity of the matrix,and the soil water characteristic curve gradually increases.When the temperature is slowed down and the residual moisture content is close to the residual moisture content,the initial grading value of the granite residual soil is low,and the water holding capacity is poor.The soil water characteristic curve is sensitive to the change of water content.(3)The shear strength test of granite residual soil under different dry density,different saturation and different vertical pressures was carried out.The research shows that the cohesive force of granite residual soil is sensitive to the change of saturation,the cohesive force has a quadratic parabolic relationship with the change of saturation,and the cohesive force changes have obvious "peak effect".the internal friction angle of granite residual soil With the increase of saturation value,the cohesive force of granite residual soil increases with the increase of dry density,while the internal friction angle changes with the increase of dry density.Finally,the granite residual soil resistance is established.The shear strength empirical formula provides a technical reference for foundation support and landslide protection.(4)Based on the theoretical basis of the shear strength test of granite residual soil,the three-dimensional finite element simulation of granite residual soil slope is carried out.The variation law of granite residual soil slope stability under rainfall infiltration effect is analyzed in depth,and granite under different dry density is obtained.The stability safety factor of residual soil slope is proposed,and the practical stability analysis method of granite residual soil slope is proposed,which provides theoretical guidance for the stability of granite residual soil slope stability and landslide prevention.