Research On The Stability Of Soil Slope Based On Shear Strength Reduction FEM

Soil slope stability analysis is involved in the geotechnic engineering and it is always performed by Limit equilibrium method, Limiting analysis and shear strength reduction Finite element method. In recent years with the development of FEM and computation methods, the study and use of shear strength reduction technology in slope stability analysis is becoming increasingly popular. The shear strength reduction technique is incorporated into the large general FEM analysis software, ABAQUS to the most critical strength reduction factor as safety factor. Through numerical computations and comparative analyses of series of typical slopes based on FEM, three criteria for evaluating instability of slope, including the abruptness of the characteristic nodal displacement, non-convergence of numerical solution or deformation at a certain characteristic location and plastic zone extension from the toe to the top of slope, are respectively discussed. The main contents of this thesis are abstracted as follows:(1) The purpose and significance of soil slope stability analysis and the merits and shortcomings are expounded, which leads to the necessity of the SSRFEM. Based on the existing problems, the objectives of this paper put forward.(2) The SSRFEM has been combined with the large finite element software ABAQUS, which has the strong functions to handle the calculated results. By manifestation of the development of generalized plastic strain in ABAQUS software, the generalized plastic strain and its development zone, delineation of the relationship between displacement and reduction factor, obtaining the safe factor of numerical non-convergence calculation can be put as the evaluation criteria for the soil slope stability. Through numerical analysis of a natural vertical slope, it is indicated that using the software of ABAQUS to analyze the soil slope stability is reasonable and valid.(3) The benefits and drawbacks of three criteria based on SSR technique are discussed. Moreover, yield criterion of soil, dilatancy, deformation parameters and FEM mesh density on the safety factor of slope stability, is examined.(4) Several homogenous soil slopes are analyzed by using the FEM based on SSR technique and their computed results are compared with the solution of limit equilibrium. The comparison shows that the safety factors computed by using the three criteria are almost identical to the solution of limit equilibrium method and indicates that the three criteria are feasibility. Meanwhile, how to select the characteristic nodal and location in the abruptness of displacement criterion is discussed in the paper.(5) Being different from all the studies before were all with the scope of homogeneous slopes, in this paper, layered slope, multi-stage slope and the instability slope were analyzed by using the three criteria. The result shows that iteration non-convergence of numerical solution is more generalized.