Slope Stability Based On Displacement Backanalysis

With regard to the open-pit mine, the joints and faults of the rock grow well and therock integrity are very poor, so the result of the rock parameters is inaccurate.Otherwise, the slope in the pit form a fragmental structure, and local area form amedium structure, water exist in the surrounding wall which bring about the instability.Therefore, determining the accurate parameters of rock mass and analyzing the slopestability are particularly important.It is on the basis of National Natural Science Foundation project “TemporalPrinciple Research of Fine Mining for Open Pit Mine”. The research object ofmonitoring are selected to observate the displacement changes of each measuring points.Part of uncertainties of parameters of slope rock mass, such as the internal frictionAngle and cohesive force, are made a sample structure based on uniform design method.The model is established by using FLAC3D program to simulate the slope displacementvalues corresponding to each group. The displacement back analysis model based on BPneural network’s performance is established by using Matlab to determine theparameters. Slope model is established by Geo-slope software. Safety factors of a slopesouth in jinduicheng open-pit mine are calculated respectively by the limit equilibriummethod of circular arc Swedish method, simplified bishop method, Janbu andMorgenstern-Price method. The results are as follow:(1)The displacement back analysis model based on BP neural network’sperformance is established by using FLAC3D and Matlab to determine the values of theparameters（the internal friction Angle and cohesive force）.(2) The parameters are applied to slope model of Geo-slope software. Safety factorsof a slope in open-pit mine are calculated respectively by the limit equilibrium methodof circular arc Swedish method, simplified bishop method, Janbu andMorgenstern-Price method. The slope is in steady state because of meeting thestandards of specification safety factor.(3) The cohesive force, internal friction Angle and density of rock mass parametersimpacting on safety factor of the slope stability are discussed in Geo-slope slope model.The concave and convex shape of slope impacting on safety factor of stability isdiscussed; Discusses the slope height, slope Angle, and the platform width impacting on safety factor of the slope stability are discussed.(4)As the standard of regulated the safety factor, the biggest slope ratio and theminimum platform width of the slope within the scope of safety, are calculated throughthe safety factor of slope stability.According to the results of monitoring displacement, the stability of slope can beanalyzed effectively through the displacement back analysis method, and the workloadof getting mechanics parameters of rock mass can be reduced.