Study On Optimization Of Mining Parameters Of Knife Pillar In Jinniu Coal Mine

Many small mines in western China have generally adopted room mining in the past.The remaining room mining pillars are used to reduce the development height of mining cracks and protect the overlying water resources to achieve water conservation coal mining.Although pillar mining technology can effectively reduce the mining disturbance of the upper coal layer,the ability of the remaining coal pillars to maintain long-term stability is crucial.Jinniu Coal Mine decided that the former pillar and pillar mining could not effectively guarantee the long-term stability of the remaining coal pillars,and decided to use knife and pillar mining instead.Therefore,this article focuses on the reasonable size of knife and pillar mining.Using theoretical analysis,FLAC^3D numerical simulation and similar material simulation and other technical means,taking the stability of the remaining coal pillars in the No.3 coal seam of Jinniu Coal Mine as the research object,the stability of the remaining coal pillars in the water-holding mining and the cutting pillar mining technology The parameters and the destruction and instability of coal pillar groups are studied to explore methods that can ensure the long-term stability of the knife pillar coal pillars.The theoretical analysis of the stability of the coal pillars left in Jinniu coal mine using knife pillar mining is carried out.Based on the ultimate strength theory,the coal pillars are calculated under the conditions of knife pillar mining width 6.0m,reserved width 7.0m and buried depth 120m.The safety factor is 1.464.This coal pillar cannot maintain long-term stability,and the research determined that the reasonable width of the coal pillar reserved for the knife-and-pillar mining in Jinniu Coal Mine should be greater than 7.2m.The physical simulation results show that the Jinniu Coal Mine originally planned to adopt a knife-pillar mining scheme,with 6.0m coal pillars and7.0m coal pillars left,but there is still a phenomenon of group instability of the remaining coal pillars.Numerical simulation analysis of the damage range and stress distribution characteristics of the surrounding rock plastic zone under different mining-retaining ratios of knife-pillar mining shows that when the width of the remaining coal pillars is greater than 8.0m,the coal pillars can still be maintained after the completion of all mining face Stable,the stress in the oal pillar cluster presents an“O”-shaped bearing area,and forms a common bearing structure with the section coal pillars,the goaf boundary and the overburden key layer;Scheme 4(mining 6m,leaving 8m)coal pillar group is the largest vertical The concentrated stress is only 5.43 MPa,and the stress distribution of coal pillars is relatively gentle saddle shape,and the bearing capacity is better.According to this,the reasonable parameters of the knife-and-pillar mining in Jinniu Coal Mine are comprehensively determined as:mining width 6m and retention width 8m;this scheme can ensure that the remaining coal pillars can maintain long-term stability.The research results provide references for safe mining under similar conditions and water resources protection and mining.There are 47 figures,10 tables and 67 references in this paper.