Stability Of Section Coal Pillar Under Influence Of Multiple Mining In Close Coal Seam Of Qiuci Coal Mine

Section coal pillar stability control is one of the key problems in safe mining of close coal seam.The stability of the section coal pillar is related to the buried depth of the coal seam,the thickness of the coal seam,the physical and mechanical properties of the coal body,and the geological structure.It is also closely related to the coal pillar size,the layout of the mining roadway and the influence of the mining stress.In recent years,scholars at home and abroad have conducted a lot of theoretical research and engineering practice on the theory and design method of section coal pillar around the problem of safe mining of close coal seam.Based on the research result of people before,this thesis addresses the problem,stability of section coal pillar under the influence of multiple mining in close coal seam of QiuCi Coal Mine,via comprehensive methods including theoretical analysis,numerical simulation,physical simulation and engineering application.The section coal pillar stress evolution rule under the influence of multiple mining is analyzed.The reasonable width of section coal pillar is determined.The effects of roadway layout on stability of section coal pillar in close coal seam are analyzed.The distribution of stress and displacement of section coal pillar under the influence of multiple mining is analyzed.The research results are applied in Qiuci Coal Mine.The research results are as follows:(1)The stress evolution law of coal pillar under the influence of multiple mining in close coal seam is obtained.The stress evolution of section coal pillar in the whole service life can be divided into six stages: I-solid coal tunneling stage,II-A501 face mining influence stage,III-A501 goaf mining influence stage,IV-A301 face mining influence stage,V-A301 working face mining influence stage,VI-A502 face mining influence stage.(2)The coal pillar retention principle of the theoretical mining section in the close coal seam is analyzed.According to the theoretical calculation,the theoretical width of section coal pillar is 6m~7.5m,and the numerical simulation method is used to further determine the reasonable width of section coal pillar should not be less than 6m.(3)The main influencing factors of roadway layout for close coal seam mining are analyzed,and the mining influence range when upper seam mining is obtained by theoretical calculation.The stress distribution and deformation law of section coal pillars under three different layouts are analyzed via the numerical simulation method.The paper determined that it is conducive to the stability of section coal pillar when the roadway layout of the close seam coal of Qiuci Coal Mine is inward staggered arrangement with a staggered distance of not less than 16 m.(4)Based on theoretical calculation and numerical simulation results,the deformation and stress distribution law of A501 section coal pillar was analyzed by physical similarity simulation method,and the ground pressure behavior of roadway of Qiuci Coal Mine were analyzed via field measurement method,which verified the effectiveness of the research results in this paper.The paper includes 54 Figures,10 Tables and 84 References.