Study On Slope Stability And Final Slope Angle Optimization Of A Kaolin Open-pit Mine

In China,open-pit mines have a large proportion,landslides,collapses and other accidents occur from time to time,and the problem of slope stability is increasingly prominent.Taking a kaolin open-pit mine as the engineering background,this paper uses the on-site investigation method,the stereographic projection method,the limit equilibrium method and the numerical simulation method to study the stability of the open-pit slope under self-weight and seismic conditions,and optimize the final slope angle.The main research contents and results are as follows:(1)Determine rock mechanical parameters such as rock density,uniaxial compressive strength and Poisson ratio of each rock layer through indoor rock mechanics experiments.(2)Analyze the intrinsic and external influencing factors of slope stability.Through the field engineering geological survey,the current slope was analyzed by stereographic projection analysis,and the analysis results showed that the stability of the current slope was good.Based on the investigation results,three rock mass quality evaluation methods are used to evaluate the strongly weathered felsite(porphyry),semi weathered felsite(porphyry),and unweathered felsite(porphyry),the results of RQD classification are poor,general and good;RMR classification results are poor(IV),medium(Ⅲ)and medium(Ⅲ);BQ classification results are soft rock(V),relatively hard rock(Ⅳ)and hard rock(Ⅲ).Rock mass mechanical parameters were calculated according to the Hoek-Brown criterion.(3)Two representative sections in the southern part of the stope were selected,the seismic impact coefficient was calculated,the stability of the final slope under self-weight and seismic conditions was analyzed by Slide software,and the Janbu method,Spencer method and M-P method in the limit equilibrium method were selected to calculate the safety factor.The safety factor calculation results of Slide software show that the final slope is stable under self-weight and seismic conditions,and the most dangerous sliding surfaces are located in strong weathering layer and semi-weathering layer.(4)The 3D solid model of the southern part of the mine was established by3DMine-Rhino joint modeling,and according to the mining design scheme,the stability of the slope in the initial state,after excavation and after the earthquake was simulated by FLAC3 D software,and the stress cloud,displacement cloud and maximum shear strain increment cloud were comprehensively analyzed,and the analysis results showed that the slope was in a stable state under three conditions.(5)According to the results of slope stability research,in order to increase the final slope angle and increase the ore output,two final slope angle optimization schemes are proposed,and the optimal scheme is determined to be a three-step parallel section according to the analysis of Slide software and FLAC3 D software.Finally,key protective measures such as slope monitoring are proposed.