| Chinese geological distribution is complex and diverse,and natural disasters occur from time to time.Among them,landslides induced by slope instability are the most serious natural disasters,and rainfall is the main cause of slope instability.Therefore,it is of great significance to study the dynamic change law of seepage field,stress field and stability in the slope body and the mechanism of slope instability under rainfall conditions,which is of great significance to the stability prediction and prevention measures of the slope.Based on saturated-unsaturated seepage theory and seepage-stress coupling theory,this paper analyzes the dynamic change law of slope seepage field,stress field and displacement field under rainfall conditions,and analyzes four rainfall factors including rainfall type,rainfall duration,rainfall intensity and rainfall cycle.The dynamic influence on the change of the seepage field and stress field of the slope;then combined with the calculation results of the coupling analysis,the change process of the slope stability was analyzed;at the same time,the relationship between the slope stability and the rainfall intensity and the saturated permeability coefficient of the slope soil was discussed.Finally,taking a project as an example,GEO-STUDIO software is used to establish a finite element model to verify the dynamic change law of seepage field,stress field,displacement field and stability,discuss the mechanism of slope instability,and propose corresponding edge Slope control measures.The specific research results of this paper are as follows:(1)With the increase of rainfall intensity,the infiltration depth of rainwater increases,the pore water pressure of the unsaturated slope increases,the volumetric water content increases,the shear strength and effective stress of the soil decrease,and a shearing force is formed inside the slope.The strain runs through the belt,the horizontal displacement increases continuously,and the shear stress concentration is formed at the step of the slope body,and the stability of the slope decreases continuously;(2)Different rainfall types have different trends in the early stage,among which the pore water pressure and volumetric water content of the uniform type and the increasing type have a larger increase;the final safety factor is:uniform type>increasing type>single peak type>decreasing type.(3)When encountering heavy rainfall,the safety factor of the slope decreases continuously;when the rain stops for a period of time,due to the hydraulic gradient between the soil layers,the surface layer of the slope responds quickly to rainfall,the deep soil responds slowly,and the upper part of the slope responds slowly to rainfall.It is still infiltrating,so the safety factor is still decreasing;as time increases,the pore water pressure in the slope gradually dissipates,and the slope safety factor gradually rises.Slopes are more vulnerable to damage at this stage.(4)When the rainfall intensity is constant,the greater the permeability coefficient of the soil layer,the greater the pore water pressure difference between the soil layers,the infiltration area and the infiltration front move downward,the pore water pressure distribution range is wider,and the shape is more uniform.tip.At the same time,the empirical formula of the ratio of slope safety factor to rainfall intensity and soil permeability coefficient is fitted.The smaller the ratio of rainfall intensity to soil permeability coefficient,the higher the slope stability.Provide some theoretical support for engineering disaster early warning.(5)For the actual project,adopt the form of anti-sliding pile support,considering the pile spacing,pile length and pile arrangement position of the anti-sliding piles,according to the results of the finite element simulation,it is obtained that the horizontal position of the slope toe and the slope of the slope are obtained.It is concluded that anti-sliding piles are set at the bottom,and the pile spacing is 2m,which can effectively improve the stability of the slope. |
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