Numerical Simulation Investigation Of Displacement Characteristic And Stability Of Unsaturated Slope Subjected To Rainfall

Rainfall-induced slope failure is a frequent geological hazard.The occurrence of landslide will inevitably cause serious damage due to the scale of slope in practical engineering is generally large.In the context of this study,a series of numerical simulation studies on the displacement characteristics and stability of unsaturated soil slopes subjected to rainfall are carried out in combination with the finite difference calculation program.In order to verify the validity of the numerical calculation program,the modeling calculation and analysis of a rainfall slope experiment were carried out first.Five representative values of rainfall intensity were obtained from the analysis of daily rainfall data in Zaoyang city of Hubei province during the three years.In order to have a deeper understanding of the displacement change law of the slope,two monitoring profiles 1-1 and 2-2 were taken on the model slope,and two monitoring points P and Q were taken at different positions of the slope.On this basis,the influence factors of rainfall characteristics,hydraulic characteristics of slope soil and soil strength of slope were analyzed respectively.After analyzing the numerical results,the following conclusions are obtained:(1)Large horizontal displacement of slope occurs in shallow soil under the effect of rainfall,and the horizontal deformation gradually decreases with the increase of depth.The development mode of the horizontal displacement of the slope is gradually extending to the deep layer with the large deformation area as the center.Under the action of rainfall,the horizontal displacement of the slope is larger at the foot of the slope,and the maximum horizontal displacement of the section 1-1 of the slope is less than that of the section 2-2.Under the influence of infiltration,the horizontal displacement of the upper soil in section 2-2 is more significant.(2)With the increase of rainfall time,the horizontal displacement of the slope tends to increase and reaches the maximum at the surface of the slope.The calculation of slope stability shows that there may be a correlation between horizontal displacement and safety factor.(3)The change of rainfall intensity has a great influence on the distribution of pore water pressure in the slope.When the rainfall intensity was low,the slope surface still had negative pore water pressure after rainfall,while when the rainfall intensity was high,the negative pore water pressure on the slope surface gradually disappeared with the rainfall process.With the increase of rainfall intensity,the horizontal displacement of the slope gradually increases.(4)The increase of effective internal friction angle makes the horizontal displacement of slope profile decrease.When the effective internal friction angle is 20 degrees,the horizontal displacement of slope changes abruptly near the soil interface.After rainfall,the higher the soil strength parameters,the better the slope stability.(5)Under the calculation conditions in this paper,the slope has a large horizontal displacement when the saturated permeability coefficient is close to the rainfall intensity value.The slope with better drainage still retains a certain matrix suction on the surface of the slope under long-term rainfall,which shows that the slope with better drainage has less deformation and better stability under the influence of rainwater infiltration.