Comparative Study On Limit Equilibrium Method And Finite Element Method For Stability Analysis Of Landslide

Landslide is a common geological disasters, deep sliding of rock and soil mass often leads to serious loss of life and property, therefore, the stability analysis of the landslide has been a research focus in related fields. In this paper two methods of stability analysis that is usually used are taken into comparison. In the basis of that the their characteristics and scope of application are clearly known, the advantages of these two methods are tentatively combined to analyse the stability of landslide. And this method is used in practical engineering, the result of landslide control is not bad.The difference of stability coefficient of these five kinds of stability analysis methods which are based on the limit equilibrium theory is not very big. Among these, the difference between the Janbu method and Sweden slice method is small, this is because this kind of method takes normal force and shear force between soil slices into consideration, and at the same time to meet equilibrium conditions of the force and moment. But the difference between the Bishop method and residual thrust method is a little bigger, this is because these two methods ignore some force between soil slices and conditions of the force and moment are not met.It shows that after comparative study:the stability coefficient of the same landslide which is analysed by the finite element method and limit equilibrium method is different obviously. In natural and heavy rain condition, the difference of the stability coefficient which is analysed by the finite element method is little. The thinking of this method:with the value reduction of c and φ of rock and soil mass, at the same time the stability is judged by instability criterion, at last the reduction factor is regarded as the stability coefficient. The discount coefficient method to calculate the stability coefficient has some defects. If whether the calculation is convergent or not is regarded as instability criterion of landslide, there may be errors due to the convergence condition set.The finite element limit equilibrium method uses the advantages of finite element method and limit equilibrium theory, so the stress and strain inside rock and soil mass could be analyzed better to avoid the errors because of some kinds of assumption from traditional limit equilibrium method. The stability coefficient calculated by this method is same as the limit equilibrium method, the stability coefficient of these two methods is the ratio of the total anti sliding force and total sliding force, so they have the same physical meaning. Compared with the traditional limit equilibrium method, the stability coefficient calculated by finite element limit equilibrium is smaller, this is because the situation of stress and strain inside the slope are taken into sufficient consideration, therefore it is more practical and the slope engineering is safer.In this subject, limit equilibrium method and the finite element method are compared and researched. Their limitations and defects of the corresponding mechanism are cleared. The advantages of these two methods are combined, and the finite element limit equilibrium method is expanded. And this method is used in the real landslide analysis to propose the targeted reinforcement measures. The research results have good reference value for the analysis of similar landslide stability and reinforcing treatment.