Research On Slope Stability Of Non Working Wall Within First Mining Area In The 3^rd Baiyinhua Opencast Coal Mine

It is an especially important topic of development for slope stability analysis method investigation in geotechnical engineering. In the stage of stripping topsoil within first mining area in the 3rd Baiyinhua opencast coal mine, the stability of composite slope constituted of non working wall and outer dump is one of the issues that need to be addressed urgently by the mine. Numerical simulation, limit equilibrium method and reliability analysis are integrated together based on FLAC3D platform, taking"stress-strain mechanical behavior","reliability"and"stability factor"as multi-indexes for evaluating, and the slope stability analysis is accomplished comprehensively by this integrated method.According to the "geotechnical engineering investigation norms" (GB50021-2001), Hawke-Brown experience strength criteria and similar engineering experience, the physical and mechanical indicators of slope rock (clay) are anlysized firstly, and the conclusion that the rock type of slope belongs to soft-half rigidity rock is drawn. Lithology, structural face, ground-water, shape of slope and outer load have important influence on the slope stability according to engineering geological qualitative analysis. The sensitivity of factors, such as friction angle, density, cohesion and ground-water, are smaller in order to slope stability according to multi-factor sensitivity quantitative analysis.During the analysis of slope stability, FLAC3D numerical model was established by softwares such as Surfer, ANSYS software firstly. With FLAC3D Numerical Simulation and strength reduction, the paper analysed stress-strain mechanical behavior of slope under the static equilibrium and solid-flow-coupled conditions, and the location and shape of potential sliding surface was defined. Then, Using the Lizheng software and limit equilibrium method, the location of potential sliding surface was certified, and the stability factors of the most dangerous and the designated sliding surface were calculated by using the simplified Bishop method and Janbu method. At last, the stability factor, which was calculated by adopting traditional limit equilibrium method, was considered as an indicator, and the potential sliding surface, which defined by the numerical simulation, was considered as specified surface, the reliability index and failure probability of slope were calculated according to the basal principle of first-order second-moment method.Through analysis, it is shown that, from different aspects by different methods and different evaluation indicators, the composite slope under the current state is in a stable state, but the local slope of Dump is under the unacceptable level of risk. Otherwise, the complicated destruction model of composite slope is the arc-shaped, plane shearing and unloading damage etc. All the researches are well accord with the actual situation at the scene.The research show that it is feasible that numerical simulation, limit equilibrium method and reliability analysis are integrated together based on FLAC^3D platform, and it will promote the credibility of slope stability evaluation, to reaching a goal, namely, appling the linear method to slove the nonlinear question of slope stability.