Discussion Of Relevent Issues On Limit Equilibrium Analysis And Finite Element Technique Of Slope Stability

Slope stability analysis is a popular geotechnical topic and it can be divided into three parts, limit equilibrium method, finite element method and limit analysis method respectively.As the slope stability analysis is a high order statically indeterminate problem, limit equilibrium method assume the slope of rock and soil mass as rigid body and import a series of suppositions about value and direction of force.Finite element method regard the slope of rock and soil mass as plasmodium,through analysing on stress distortion of the slope,stress distribution of the slope mass can be calculated. Limit analysis method carries through analysis with assumption of the slope of rock and soil mass as rigid body and sliding surface as plastic body.Both of limit equilibrium method and finite element method above are only discussed in this paper,the main research work carried out are listed below.1.The finite element mesh are carved to be vertical ones,corresponding to the vertical bars in sliced method. The stress of finite element results is transformed to be the force between the soil slices in order to contrast with the one in limit equilibrium method. The finite element method results and other limit equilibrium methods results are compared, including the force between the soil slices,the normal stress of the sliding surface and the point of the force between the soil slices.2.This paper proposes a new method to construct an interpolation function to search the most dangerous slip surface of a slope in the finite element method results and use Excel to search for the slope sliding surface using the most dangerous slip surface direction of each unit of the finite element analysis results.The interpolation functions ofσx,σy,τxy,αof the finite element analysis results are respectively constructed. The normal stressσ, the shear stressτand the sliding surface angle a on the sliding surface are calculated by calling the interpolation function. Stability factor can be solved by using the ratio of resist shear force to shear force.3.With the constructed interpolation function ofσx,σy,τxy, the finite element method results are applied to any case of slip surface. This paper summarizes that limit equilibrium method is a special case in whichσy=γh of the stability factor can be solved by applying the stress of each point. Limit equilibrium method is an imprecise method and thus finite element method is on the contrary. The reason why the relatively accurate method is not widely used may be due to its inconvenience to engineers or immatureness. This paper imposes simple Excel spreadsheet to search slip surface and caculate the stability factor using the finite element method results. This finite element method approach is very simple in practice and can be taken into practical application comfortably.