Model Test And Numerical Analysis Of Granite Residual Soil Slope Under Drying-Wetting Cycles

In the natural environment,various types of slopes are affected by rainfall and the sunshine process.During rainfall,rainwater infiltrates into the soil,and the soil gradually softens and its strength decreases due to the increase of moisture content.During sunshine,the surface temperature of the soil rises,water vapor in the soil evaporates into the air,and the moisture content of the soil gradually decreases,shrinkage cracking occurs.When continuously receiving rainfall and sunshine cycling effects,the soil continues to expand and shrink,and its mechanical properties gradually change during this process,the interaction between soil particles is weakened and the stability of the slope is reduced.When the intensity of rainfall is greater,it may be.Destruction will occur.Therefore,it is very important to study the response of the slope under the dry and wet cycle.In this paper,a model test of the slope of granite residual soil under the drying-wetting cycles were taken,and the change of water content and suction force of the slope with water content sensor and tensiometer are measured.And the samples on the slope were taken for direct shear test to measure the shear strength.The suction force of the sample was measured by the filter paper method.At the same time,the development of surface cracks and the deformation of the side surface of the model slope were observed.Two model boxes were simultaneously tested to compare the slope response at two different drying-wetting cycles.The experiment found that in the drying process,the moisture content becomes larger with the depth;with the increase of the number of drying-wetting cycles,the maximum suction and cohesion at the same depth of the slope are gradually reduced and tend to be stable;and internal friction with the increase of the number of drying-wetting cycles,there is no obvious rule;the number of cracks on the surface and sides of the slope increases with the increase in the number of drying-wetting cycles,the width of cracks broadens,and the number of cracks at the foot of the slope is the largest,compared with the cycle amplitude.The experimental results show that,with the increase in the number of drying-wetting cycles,the drop rate of water content,suction,and cohesion at the same depth in the slope under the large-cycle amplitude test is larger than that in the small-cycle amplitude test,and cracks developed on the slope surface also more.The above results all reflect to a certain extent the response of the slope under rainfall-sunshine conditions.Through the numerical simulation analysis of the fluid-solid coupling of the slope,it was found that the matrix suction decreased with the increase of the number of drying-wetting cycles,and the longer the rainfall time,the greater the decrease of the matrix suction.According to the stability analysis of the slope,it is found that in the calculation process,the plastic zone of the slope gradually develops along the slope from the slope foot,and finally runs through the slope;the safety factor of the slope also decreases with the increase of the number of dry-wet cycles.