Research On Delineation Of Security Pillars Based On Safety Depth Theory And Moving Angle Optimization

In order to ensure the safety of the shaft,the safety pillar is usually delimited around the shaft with a certain rock movement angle.Compared with shallow mining mines,deep mining mines are difficult to ensure resource output and shaft stability at the same time.The existence of security pillars is bound to overstock a large number of orebodies.This study is aimed at Xinda gold mine,which has serious pressure,In order to protect the main shaft in the moving zone,a safe distance of 20m is set at the wellhead,and 65°the security pillar is delineated by moving angle.Up to the middle section of 168m,the ore yield is about 2.67million tons.The economic burden will be caused to the mine if all the pillars are recovered by filling method.By optimize the boundary of security pillars,improve the ore output on the premise of ensuring the safe and stable operation of shaft,3D mine model of Xinda gold mine is established by using 3DMine-Rhino-FLAC^3D coupling,so as to reduce the changes of surface and ore body strike and improve the accuracy of numerical simulation results,using the method of numerical simulation and theoretical calculation to calculate the safe depth under the condition of deep mining,improve the accuracy of safe depth prediction,and optimize the movement angle of Xinda gold mine.The safety depth and the optimized movement angle are taken as the criteria of safety pillar delineation.Finally,it is verified by numerical simulation,which provides a theoretical basis for shaft safety pillar delineation in deep mining.(1)Based on the established three-dimensional numerical model of Xinda gold mine,this paper simulates the stability of shaft under two different working conditions of whether to leave security pillars or not.By comparing and analyzing the deformation characteristics of shaft under two working conditions,the stability status of shaft is obtained,and the deformation mechanism of shaft is summarized and analyzed,The safety pillar of Xinda gold mine is optimized by the combination of rock movement angle optimization and safety depth.After optimization,the pillar boundary will extend vertically downward below the safety depth,greatly reducing the width of the pillar along the strike direction and releasing the overstocked ore bodies on both sides of the pillar.(2)The movement angle of Xinda gold mine along the strike direction and tendency of ore body is calculated by numerical simulation,and the optimized movement angle of Xinda gold mine along the strike direction of ore body is 75°,the movement angle of ore body dip direction is 65°,the safety depth of Xinda gold mine is 496m below the surface by using the probability integral method.Combined with the numerical simulation analysis,the deformation of the surface and shaft is integrated,and the safety depth of the mine is finally determined at the middle section of 658m.The safety depth and the movement angle are combined to get the optimized boundary range of the safety pillar.(3)Finally,FLAC^3D is used to simulate and verify the feasibility of the optimized safety pillar.The deformation of the shaft and the surrounding surface above the shaft is not significantly increased compared with that before optimization,and the deformation value is always within the specified safe range of 10-15mm,indicating that the optimization scheme is feasible.The safety pillar can release 780 000 tons of overstocked ore body while limiting the movement of hanging wall rock,At the same time,it can ensure the stability of the shaft and surface buildings,improve the economic benefits of the mine,and provide a certain theoretical basis and basis for the delineation of security pillars in similar mines.