Study On Mechanical Properties And Slope Stability Of High Liquid Limit Red Clay Under Dry-Wet Cycle

High liquid limit red clay is widely distributed in southern China,with many bad engineering characteristics.With the economic development of southern China,more and more highways need to pass through the high liquid limit red clay area,which requires us to further study the characteristics of high liquid limit red clay and slope stability.This paper takes the high liquid limit red clay in Hainan as an example,combined with the local dry and wet traffic Based on the laboratory direct shear test,scanning electron microscope test and mercury intrusion test,the mechanical properties of high liquid limit red clay under the action of dry and wet cycles were studied.The slope model of high liquid limit red clay was built,and the stability of high liquid limit red clay under the action of dry and wet cycles was studied by numerical simulation.The main research results are as follows:(1)The higher the initial moisture content of high liquid limit red clay sample,the lower the shear strength.Under the action of multiple dry-wet cycles,the shear strength,internal friction angle and cohesion of high liquid limit red clay all show a downward trend,and tend to be stable after three cycles.The decrease of cohesion is greater than that of internal friction angle,which indicates that the decrease of shear strength is mainly caused by the decrease of cohesion.(2)SEM and MIP results show that the pore content of high liquid limit red clay increases under the action of multiple drying and wetting cycles,and most of the pores are distributed in the range of 0.01-0.1 μm and 10-100 μm,and the percentage of macropores and ultramicro pores is much higher than other pore types.The mechanism of drying and wetting cycles on high liquid limit red clay is explained from a micro perspective Li.(3)According to the model test results,the water content,pore water pressure and matrix suction at different positions and depths of the slope change periodically with the dry-wet cycle.The closer the slope is to the surface,the more obvious the change is.The influence mechanism of simulated rainfall stage can be explained by Darcy’s law and erosion.In simulated sunshine stage,the evaporation of slope water is mainly caused by temperature rise.(4)According to the layered strength theory,the finite element method is introduced to optimize the simulation model.According to the calculation results,the safety factor of the slope decreases gradually after the dry wet cycle,and the potential sliding surface of the slope tends to move to the surface.If the slope is damaged,the damage location will be more and more concentrated in the area below the surface of the slope.