A Study On The Variation Of Clay Properties And Slope Seepage Stability In Wu Xiang Area With Multiple Dry-wet Coupling

The coupling effect of moisture and heat brought by natural rainfall and evaporation has many adverse effects on the structural properties of soil,and then affects many engineering construction.Therefore,it is of great significance to study the changes of structural properties of soil under the dry wet cycle.In this paper,drying method and water film transfer method were used to simulate the process of dehumidification and humidification respectively.In the process of drying wetting cycle,the crack evolution of soil surface is studied by means of digital photography and computer technology.After that,the micro test,strength test,permeability test and expansion test are carried out for the soil samples before and after multiple dry wet cycles,and the specific influence of dry wet cycles on the engineering properties of clay is comprehensively understood by combining the micro characteristics with the macro properties by using the gray theory.Finally,based on the indoor test results,the finite element simulation of clay slope is carried out to study the influence of dry wet cycle and cracks on the slope seepage stability.The main achievements of this paper are as follows:(1)During the process of dewetting,the clay appears obvious drying shrinkage phenomenon,and the drying shrinkage degree of dry soil becomes larger after multiple drying and wetting cycles,and the drying shrinkage first changes from the surrounding drying shrinkage to the middle shrinkage cracking first;during the process of dewetting,large main cracks appear in the middle of the soil surface,and small cracks develop around the soil surface.With the increase of drying and wetting cycles,the soil becomes more fragmented,and the soil surface no longer maintains this kind of main cracks It is a large fracture developed randomly.(2)The micro-pores of clay soil are large and the pore size distribution is wide,and the particles are in contact with each other in the form of surface-surface and surface-side.The dry-wetting cycle causes the particles to be destroyed and transformed into small particles,and the particles become smaller and broken,and the pore diameter between particles also tends to decrease.(3)The strength of clay decreases greatly before and after wetting and drying cycles,and the permeability of soil increases by orders of magnitude after several wetting and drying cycles,while the no-load expansion rate of soil is negatively correlated with the number of wetting and drying cycles.According to the grey theory correlation degree calculation,the four kinds of soil particle morphology characteristics all have certain influence on water migration in soil,so they all show certain correlation with soil macroscopic properties.(4)After multiple wetting and drying cycles,the slope stability decreases greatly,the rainwater infiltration depth increases greatly,and the position of the most dangerous slip surface moves upward,that is,the slope is more prone to shallow landslide after multiple wetting and drying cycles.The crack has a great destructive effect on the stability of the slope,and the rainwater increases the infiltration depth through the crack,making the position of the most dangerous slip surface of the slope close to the shallow area of the slope,that is,the crack also makes the slope prone to appear shallow landslide phenomenon.