Shear Strength And Slope Stability Analysis Of Phyllite Residual Soil

Longsheng is located in the phyllite stratum,high weathering degree,widely distributed with phyllite residual soil.Under typical climatic conditions,phyllite residual soil is unsaturated,soil strength and slope stability are obviously affected by moisture,and the shear strength of soil decreases;during high temperature evaporation,the soil shear strength increases,which affects the stability of the slope,so the soil strength problem of water content change is the key to solve the slope instability,which is of great significance for the prevention of landslide and other disasters.With the study of phyllite residual soil in three different regions in this paper,a series of studies are focused on the shear strength of phyllite residual soil,mainly including the following aspects:(1)The influence of different water content and different dry densities on the shear strength of three kinds of phyllite residual soil was studied,and the shear strength of soil with different water content and different dry densities was obtained through the consolidation fast shear test.The results show that the shear strength of soil decreases with the increase of water content,and the shear strength of the same soil is 1>2>3.Using the scanning of three phyllite residual soil,the results show that the soil particles with high dry density samples in the same soil samples are more structured,and the soil particles is more dense under the same conditions.No.2 soil is the second,and no.3soil has more large soil particles,and the small size soil particles used to fill are very small.The large pore filling in the soil is particularly obvious,resulting in low strength.Therefore,the size comparison of the three soil shear strength can be explained from the microscopic perspective.(2)Using pressure plate method and saturated salt solution method studied the holding water of phyllite residual soil.The experimental results show that the greater the dry density of the three kinds of phyllite residual soil,the higher the intake value,the better the holding water of the soil,and the greater the residual saturation.The order of the three soils at the same dry density was 1>2>3,which is the same as the order of shear strength.The NMR technology explains the pore water changes of the three kinds of soil in the dehumidification test.The sample first exits the water in the large pores,and then reaches the water in the small pores.The difference between no.3 soil and the other two kinds of soil is that there is no bimodal structure at all,and the large pore is the main way of pore existence.(3)Fitting the measured value of soil-water characteristic curve of three kinds of phyllite residual soil;Ffitting using three common models,Such as VG model,FX model as well as GA model,From a simple comparison of the fitting accuracy of the three models,we can see that the FX model is the most suitable for the special soil of phyllite residual soil,This is due to the FX model by introducing a modified parameter,Make the vertical axis on the image 0 at 10~6k Pa,This makes the curve of the FX model more complete compared to the VG and GA models,To better express the water-holding characteristics of the soil in the wide absorption range.(4)Based on Geostudio finite element numerical simulation and analysis software,the soil-water characteristic curve fitting parameters of the three kinds of phyllite residual soil are replaced into the software to analyze the stability impact of rainfall on the soil slope of the three kinds of phyllite residual soil by simulating rainfall and calculating the slope safety factor during rainfall.