Local Strength Reduction Method Of Slope Analysis And Its Engineering Application

Taking slopes as the research object, based on the typical all strength reduction methodand according to the force mechanism of slope failure, this paper proposes the local strengthreduction method to analyze the slope stability, and combine the variable moduluselastoplastic model to simulate the stress field and the deformation field of slopes. This papertries to obtain the relationship between the safety factor and the displacement during thefailure process of slopes, which can give guidance to the actual slope monitoring.The finite difference software-FLAC3D is used as the analysis platform. First,FLAC3D’s mechanical background, features, calculation equations, and calculation processare introduced. Considering the weakness of FLAC3D’s preprocess, this paper based on thepowerful modeling function of Midas/GTS introduces how to transform the model grids fromMidas/GTS to FLAC3D. This modeling method can build complex slope models of highefficiency and quality in FLAC3D, thus addressing the weakness and difficulties inFLAC3D’s preprocess, which offers a new way for complex engineering modeling inFLAC3D.Second, the local strength reduction method on slope stability analysis is entirelydiscussed. Actually, most natural slopes become instable when the strengths of local soils arereduced. Once those soils are weakened to some degree, the displacement of the slope surfaceis very obvious and the slope is close to failure. Therefore, in terms of the failure mechanismof the slope, the displacement by local strength reduction method is more close to the reality.Also, that displacement is less than the displacement by all strength reduction method.Third, this paper introduces the variable modulus elastoplastic model, which is improvedbased on the Duncan-Chang model. This constitutive model modifies the soils’ deformationparameters according to the stress level of soil elements, which better reflects the plasticfeature of soils and is coincident with soils’ deformation mechanism; thus, the deformationfield obtained by this model is closer to the reality. In addition, this model just needs severalparameters, which can be determined through in-situ tests, so it is easy to apply. The analysisresult of the Wuhua slope discussed shows that it is feasible to compute the displacement ofsoil slope by the local strength reduction method and the variable modulus elastoplastic model.Finally, this paper applies the local strength reduction method and the variable moduluselastoplastic model in the stability analysis of Egongdai ancient landslide in Lechangxia. Thesafety factors of the landslide before and after reinforcement are given, and the limitdisplacement of Egongdai ancient landslide under different water level is studied, which giveguidance to the actual monitoring of that landslide.