Analysis Of The Stability Of Xi Jikeng Lead-zinc Mine Goaf And Optimization Of Its Treatment Plan

Lead and zinc minerals are widely distributed in China,but find out the main relative resources concentrated in several provinces and autonomous regions,and as the main hub of lead-zinc mine in Guangxi,the tasks of the lead-zinc mine mining supplies,however,with the development of lead-zinc mineral resources exploitation,the legacy of near-surface goaf on the surface of basic farmland constitutes a serious harm,at the same time,the safe hidden trouble of lower mineral mining,reasonable and effective governance goaf,prevent the surface subsidence and protect the safety of lower mineral mining has important practical significance.In this paper,according to the ore storage conditions of Xi Jikeng Lead-Zinc Mine and goaf actual situation,based on the Bieniawski strength formula and core area strength theory to proves the stability of goaf pillar,at the same time,based on the limit analysis method and the small deformation thin elastic mechanics theory method to verify the stability of goaf target roof,combining 3Dmine,Midas GTS NX to build the mine numerical geometric model,using FLAC3D to deduce the formation process of the goaf,and the treatment plan is optimized.The main achievements include the following aspects:1.There are nine ore pillars in no.1 goaf in an unstable state;Only one ore pillar in no.2 goaf is in an unstable state;There are four ore pillars in the no.3 goaf in an unstable state;The ore pillar of no.4 goaf is stable.There are four ore pillars in the no.5 goaf in an unstable state;A total of 22 ore pillars are in an unstable state.2.The target roof of no.1,2,4,5 and 6 goaf are all in stable condition;No.3 goaf is near the ground,result in six target roofs are in an unstable state,which are A3-1,A3-2,A3-4,A3-5,A3-6 and A3-7 roof.3.Based on the theory of limit analysis method and the small deformation thin elastic mechanics theory method analysis of the target roof which is on account of unstable ore pillars collapse resulting in roof exposed area enlarged,show that unstable ore pillars collapsed chain effect will lead to further solid roof collapse,so it is necessary to implement reinforcement for unstable pillar engineerings,avoid the collapse of the roof caused by the chain collapse of the unstable ore pillars.4.The maximum principal stress nephogram of numerical simulation show that the goaf roof of compressive stress is consistent with the theoretical calculation,the ore pillar in goaf under high vertical stress like the theory calculation;The minimum principal stress nephogram of numerical simulation shows that the roof of no.3 goaf is mostly tensile stress state,and there is a large probability of tensile failure.Plastic to distinguish the layout of numerical simulation show that no.1,2,4,5 and 6 goaf which vast majority of roof does not appear the plastic damage,no.3 goaf most roof tensile failure,small area is in the midst of the tensile failure.5.Based on the numerical simulation analysis compared the treatment plan one and two,the following conclusions:both of the goaf after treatment by plan one or two,overall can transfer or reduce the goaf pillar and the roof of the corresponding effect of maximum principal stress,shear stress and tensile stress,decreases the area to the plastic area at the same time,and plan two is more effective than the one,so the proposed plan two as goaf treatment solutions.6.According to the results of the theoretical analysis and numerical simulation analysi,the design adopts the recommended plan two to treatment the goaf,through the optimized design and make concrete construction plan?construction schedule,show that the recommended plan has the advantages of strong operability,economic and convenient.