Earth Slope Stability Analysis Of Two-dimensional General Limit Equilibrium Method

The limit equilibrium approach is the earliest and most extensive method in the application of the slope stability analysis, Its basic idea is to assume a surface which is likely to fail and try to find a state of stress along the surface so that the free body is in static equilibrium. The method makes some assumptions in order to make the question that is indeterminate in nature to be solved. Because of different assumptions, there are several mothods, some of them are satisfactory in theory. Various method have various expression, and satisfy force equilibrium conditions in various degrees. Based on the limit equilibrium theory and conception, this thesis suggests a new common limit equelibrium method which can deduce other method in some given conditions. The study is mainly as fowllows:(1) Pan Jiazheng's minimal and maximal principle is the basic rule in slope stability analysis. They are summed up from engineering practice, and have theory foundation. The minimal principle is used to find the critical slip surface, as is validated in this paper. When we analyse rigid body with the theory of limit equilibrium, we do not obtain always reasonable maximal principle in physics, and the maximal value is the result of soil plasticity deformation.(2) Thoroughly commenting the typical method of slices from their satisfid equilibrium conditions, calculational parameter and their convergence, the thesis sortes the methods into four kinds. The first satisfies all kinds of equilibrium conditions, can obtain interslice force and the factor of safety. The second only satisfies one directional force equilibrium and moment equilibrium, merely obtains the factor of safety. The third satisfies force and momen equilibrium, but it is not rigorous static question and has slow convergence speed.The fourth satisfies force equilibrium of two directions, not moment equilibrium, and can get magnitude of interslice force and the factor of safety, not direction of interslice force.(3) Based on analyzing former methods thoroughly, a new generalized limit equilibrium method which is satisfied arbitrary sliding face is proposed. The method, in which the interslice force is assumed as uniform form, establishes numerical integral formula of safety factor respectively based on the force and moment equilibrium and the formula of sliding force and its point of application at arbitrary transect to satisfy the actual project requirements.