Study On Method Of Soil Slope Stability Analysis

Slice method and finite element method are principal methods of soil slope stability analysis. Strength Nonlinear, pseudo-static method and FE slope stability method are studied. Some conclusions are obtained and improved and new method are put forward.(1) Safety factor calculated with non-linear strength and application. The Mohr failure envelop for rockfill exhibit significant curvature. The strength envelop is non-linear. The compare of safety factor of 8 high rockfill dams with non-linear strength and with linear strength indicates that safety factor of non-linear analysis is bigger than that of linear analysis. The slip surface of linear analysis is shallow, but the slip surface of non-linear analysis is deep. Based on statistical result of 156 specimens, allowable safety factor in Rockfill Dam Design Criterion (SL274-2001) based on linear rule should be properly increased. This paper suggested it is increased by 8% as non-linear strength used.(2) Improvement on pseudo-static method of slope stability analysis. Pseudo-static method of slope stability analysis is used widely and play a distinctive role in slope seismic stability. Sliding mass is traditionally divided by vertical slice. Errors should be induced in calculating horizontal seismic inertial force and anti-sliding moment according to vertical slice. Anti-sliding moment is underestimated. When horizontal seismic inertial force in foundation is taken into account, safety factor is uncertain. The cause of errors and uncertain is analyzed, and a improved method is put forward. Calculating sample shows the improved method is reasonable, that is, safety factor is certain and less then old method.(3)Criteria of slope failure of shear strength reduction method. The key of shear strength reduction method is that how to define the failure of slope. There have been several criteria proposed in the literature to define global slope failure in a finite element analysis, such as bulging of the slope profile, limiting shear stresses on the potential slip surfaces, and non-convergence of the numerical solution. The factors of safety from some of these criteria may be subjective and inconsistent. These criteria are discussed. New method to define safety factor is put forward. The method is based on the curve of the maximum horizontal displacement and coefficient reduction, and can reflect the gradual failure of slope. (4)FE slope stability method based on slip stress optimized. The key of stability method based on slip FE stress is stress of slip. Traditionally, stress on slip is obtained by interpolating in a element, thus stress discontinue is induced. A optimized method is put forward. Stress around slip is smoothed in sub-area, and stress on slip is get by extrapolating, so stress on slip is smoothing and up to fact.(5) FE circular arc sliding method. Traditionally, slope FE stress field and minimum safety factor are calculated independently. A method for stability analysis of slopes based on finiteelement stress analysis is introduced. The method combined FE stress calculating and minimum safety factor searching by adaptive and refined meshing techniques, and slip stress can get directly. The method is applied in stability analysis of CHANGHE rockfill dam. The safety factor of construct stage is closed to BISHOP method', but the safety factor of water storage stage is different from BISHOP method'. The FE circular arc sliding method is veracious, because stress calculated is more actual.