Delimitation And Stability Analysis Of Safety Pillar Of Blind Shaft In Xinda Gold Mine

The mining of underground ore body will inevitably lead to the movement and deformation of the overlying strata.If the movement and deformation exceeds a certain range,the surface and underground roadway engineering will be damaged.Therefore,the mine will reserve security pillars to protect the shaft.However,for the mine that has entered the stage of deep mining,the traditional method of security pillar delineation is too limited,It will lead to a large number of high-quality mineable bodies located in the range of security pillars,which can not be mined.For this problem,there are no mature theoretical results and convenient calculation methods at home and abroad.Xinda gold mine,the research object of this paper,is a typical metal mine which has entered into the deep mining stage.The mining depth of this mine is large,and the problem of security pillar pressing is prominent.Through collecting relevant data,engineering geological survey,theoretical analysis,numerical simulation and other means and methods,this paper studies the boundary optimization problem of safety pillar in blind shaft of Xinda gold mine.The main work of this paper is as follows(1)Based on the analysis of the stability of goaf under the support of granular body,it is concluded that the active side pressure and passive side pressure of granular body hinder the further caving of goaf rock mass,and the passive side pressure plays a leading role.Based on the theory of critical granular column support,the method of filling goaf with waste rock is used to control the movement range of overburden rock.PFC is used to simulate the displacement change of surface and hanging wall rock mass after ore body mining.The collapse range of surface and the height of critical granular column are obtained.The simulation results show that the height of critical granular column gradually decreases with the increase of ore body dip angle.According to the height and movement angle of the critical granular pillar,the safety pillar of the shaft is re delineated,which effectively solves the serious problem of the safety pillar pressure.(2)Based on Hoek Brown strength criterion,the strength parameters of jointed rock mass are calculated.The double yield model is used to invert the mechanical characteristics of waste rock compaction process in goaf,and the mechanical parameters of waste rock filling body are obtained.Using 3D mining engineering software 3DMine,3D modeling software rhino5.0 and griddle mesh generation software,a FLAC3 D numerical calculation model close to the actual mine is established.(3)FLAC3D is used to simulate the mining of No.13 orebody.Firstly,the stability status of shaft after mining of No.13 orebody is analyzed.Through the simulation results,the rationality of numerical model and mechanical parameters is verified.Then,the mining analysis of No.32 orebody outside the scope of Baoan pillar is carried out,and the stability of the shaft when it is excavated to different middle sections is summarized,and the overall deformation mode and vulnerable area of the shaft are obtained.The research results show that after the waste rock filling in the goaf,the influence of the excavation disturbance of the ore body on the shaft is small,and the shaft is in a stable state,which indicates that it is reasonable to delineate the security pillar based on the critical granular pillar theory.