Research On The Instability Criterion Of Slope Based On Shear Strength Reduction Finite Element Method

With the development of national economy, construction, railway, highway, water conservancy and urban infrastructure construction are flourishing, these projects all involve the issue of slope stability. Slope instability not only affects the normal use of buildings, but also brings heavy losses in human life and property. Therefore, the slope stability analysis has theoretical significance and practical value, so we should cause enough attention.The methods of slope stability analysis are the limit equilibrium method and the finite element strength reduction, the latter has obvious advantages due to the consideration of the geometry shape of slope,soil constitute model and nonlinear load, so is widely applied to practical engineering. Based on the theory of finite element strength reduction, different failure criteria the convergence of numerical computation criterion, the connectivity of plastic zone criterion,the mutation of displacement criterion and the catastrophe of plastic strain energy criterion are built for the same calculation model.These criteria are analyzed and compared. The specific research contents and conclusions as follows :(1) Based on the finite element strength reduction theory, combining with the finite element software ANSYS, the convergence of numerical computation criterion, the connectivity of plastic zone criterion,the mutation of displacement criterion and the catastrophe of plastic strain energy criterion as criteria, we calculate the safety factor of the same slope. These criteria are analyzed and compared. It draws conclution that the catastrophe of plastic strain energy criterion is less affected by the outside factors and the safety factor is more accurate.(2) Based on the catastrophe of plastic strain energy criterion,it studies the influences of soil parameters on the slope safety factor. It is concluded that the cohesive force and internal friction angle have large influences on the safety factor, the elastic modulus, poisson’s ratio and dilation angle has no unremarkable impact on the safety factor.(3) Combining with the specific engineering example, establishing a three-dimensional numerical model, the catastrophe of plastic strain energy criterion as the criterion, we calculate the safety factor of the slope to determine the stability of the slope, so that it lays the theoretical foundation for later study.