Slope Stability Analysis Based On Critical Stable State

Frequent landslides and slope failures have been not only posing a great threat to the lives and properties of human beings, but also created a great deal of troubles for the numerous infrastructure constructions and other human’s activities. An effective slope stability analysis method and evaluating the stability of these slopes reasonably and accurately are of great importance for the landslide forecast, prediction and treatment and minimizing the losses brought by landslide hazards. Considering this, some researches were conducted as follows:(1) A series of simple slope examples were analyzed by using the two-dimensional Morgenstern-Price method to obtain the factors of safety defined based on the margin of shear strength, and the changing trends of factors of safety with regard to mechanical parameters or external environmental factors, such as the external loads and seepage, for slopes also compared with each other. The physical meaning of the factors of safety those equal units was proved theoretically, The concept of critical stable state and the critical state line (surface) concept for slopes were proposed and then a new method based on critical stable state to evaluate the stability of slopes was dicussed initially and recommended.(2) A limit equilibrium method that satisfies the three force equilibrium conditions of all columns and three moment equilibrium conditions of total failure mass is proposed, in which the interslice forces are assumed by proposed lateral shear factors and lateral shear distribution functions. The present formulation can be treated as an extension of the two-dimensional Morgenstern-Price’s technique. The increment relationships between the intercolumn shears and normal forces are introduced to the formula derivation so that all unknowns can be expressed by some equations, the factor of safety of each row (column) is obtained by solving the force equilibrium equations and the boundary conditions of total failure, and then the lateral shear factors are determined by solving the torque-equilibrium equations for total failure mass. All intercolumn forces are taken into account in calculating factor of safety. The direct iterative algorithm is implemented in the program developed by the authors to improve the computational efficiency markedly. Several examples ware analyzed to validate the proposed three-dimensional formulation and developed code and its affectivity to deal with complex slopes (asymmetric slip surface with weak layer).(3) The recommended method based on critical stable state, the developed three-dimensional limit equilibriurn model and the combination of them were applied to evaluation of the stability of the slopes at a municipal solid waste landfill in Chengdu, Sichuan, China. The results showed the superiority of the critical equilibrium state method and the capacity of the three-dimensional equilibrium model to solve complex practical engineering slope problem was also further validated. Furthermore, some valuable advices were provided for the design, construction, running and management of the Landfill.