A Comparative Study Of Limit Equilibrium Method And FLAC - 3D Simulation Method In Slope Stability Analysis

Limit equilibrium method (LME) and the FLAC-3D numerical simulation are two of the commonly used method in slope stability analysising, they all have corresponding characteristics but remains to be perfected. In this paper, the difficulties of FLAC-3D modeling directly are solved by means of drawing software and finite element analysis software. Combining with an engineering example, comparative study clarifies the error mechanism of the two methods, and the imagines are put forward, such as the combinated using, the mutual authentication and the relay calculation.The error of the limit equilibrium theory mainly stems from the following several aspects: First of all, the work way and location of the force in the slope soil are simplified; then the number of divided slices has a larger number of randomness; at last, circular slip surface just consistents with homogeneous soil slope, and there is a certain randomness and subjective factors in other sliding surfaces. The sliding surface of actual project is given by experience, this results in the sliding surface in most of profiles are not consistent with the calculation results, so the sliding surface is not specified as the limit equilibrium method, in which the sliding surface is strict in the rock interface of Quaternary landslide accumulation layer and strong weathered mudstone layer.When using the limit equilibrium method to study the slope stability, a variety of different models are advised to choose for calculating the same object, and then calculats an average from all the results with the expectation of reducing the error caused by a single model.FLAC-3D numerical simulation method focus on the analysis of stress and strain in geotechnical engineering, it is more consistent with the actual process of slope deformation and destruction. But the accuracy of the simulation results are also affected by the unit grid division. This software can research geotechnical objects in three-dimensional, and can give full consideration to the rock distribution and the deformation coordination between layers, so that the geological structure characteristics consistent with the actual situation. So, it is more accurate and intuitive when compared with the two-dimensional analysis. What’s more, FLAC-3D displays the plastic strain increment cloud of profile, which shows the potential sliding surface and sliding perimeter clearly, even gives the quantitative displacement of different areas.Several difficulties exist in three dimensional numerical simulation for potential landslide, such as complex modeling process, long calculation process and cost much more time than the limit equilibrium method. Therefore, it is recommendated that drawing software GoCAD can be used to extract point data and interpolate in Surfer, then establish three-dimensional slope model in Ansys, in the end, import the model into FLAC-3D for value calculating by means of model transform plug-in.In the analysis of slope stability, such suggestions should be taken:to combine the advantages of the two methods that are described above; to authenticate mutually; and to do relay calculation.