Analysis Of Slope Stability Based On Actual Stress State

Slope engineering has always been a hot issue in geotechnical research,especially in Chongqing,Sichuan and other places.Due to the a good deal of mountains and many slopes,the instability of slope is very likely to cause greater local ecological economy and threaten people's safety.So it is necessary to strengthen the study of slope stability anlysis.Starting with two key issues in slope stability research,namely the determination of the slope slip surface and the determination of the safety factor,the slope stability is analyzed based on the actual stress state inside the slope body.At first,this article points out the defects of the vector sum method.In determining the safety factor of the slope,this paper points out the defects of the vector sum method.The direction of the slope sliding trend specified in the vector sum method is obtained only by experience.In theory,the instantaneous glide direction should be perpendicular to the normal force vector sum direction,because Considering the instantaneous sliding,the normal force does not do work,so the normal force vector does not do work.The instantaneous sliding direction should be perpendicular to the normal force vector,in the opposite direction of the ultimate friction resistance,this is the new definition of the slope overall sliding trend direction.Based on this definition,the resultant force method is proposed.This method does not need to calculate the stress state of each unit body on the sliding surface,the calculation is simple,and the physical meaning is clear,The shape and position of the slope sliding surface were determined based on the maximum shear strain increment and the curve fitting.Secondly,this article explored the actual failure mechanism of the slope.Based on the evolution process of the plastic zone of slope and point pair analysis,it is found that the rock-soil slope did not instantaneously destabilize,but generally shear failure occurred locally(slope bottom)first,and then gradually expanded to the top of the slope,and the CWFS strength was also proposed.Based on the theory,combined with the analysis of the combined force method,the stability of the slope is analyzed,and the following conclusions are finally obtained:(1)it is found that the peak strength calculation overestimates the safety factor of the slope,and the residual value strength calculation underestimates the safety factor of the slope.Considering that the strength parameters are not synchronized to reflect the slope of the soil more realistic The steady state and the mechanical properties of the soil,the safety factor obtained is also more real;(2)the crack surface obtained by exerting the strength is between the peak surface and the residual strength.(3)If there is a large difference between the peak value and the residual value of the strength parameters,the difference in the safety coefficient calculated according to the peak strength,residual strength and exerted strength is also large according to the resultant method.Finally,based on the example of the slope engineering of the green lake ring road of Bishan Mountain in Chongqing,the vector sum method considering the unsynchronized strength is applied to the stability and analysis of the unstable slope of the road fill subgrade,and the current subgrade instability main reason.Finally,the rationality and accuracy of this method are proved.