Reasonable Staggered Distance Of Thick Coal Seam And Co-mining Working Face And Reserved Coal Pillars In Sections Technical Research

Under the influence of mining in the same working face of the thick coal seam,the selection of the staggered distance between the upper and lower working faces of the same working face and the reasonable retention of the coal pillars in the section are to ensure the stability of the floor of the upper coal seam working face and the stability of the surrounding rock of the roadway of the same working face.The selection of mining staggered distance and the retention of coal pillars in sections are related to coal seam burial depth,coal seam thickness,coal seam dip angle,coal seam spacing,overburden characteristics and other factors,and are closely related to coal seam mining disturbance and other factors.This paper takes the first working face of the 212 and 515 mining areas of Qifeng Coal Mine as the research background,aiming at the problem of the staggered distance of the same working face and the retention of coal pillars in the thick coal seam,on the basis of coal and rock mechanics experiments,using theoretical calculation,numerical analysis,numerical analysis Simulation and other research methods are used to systematically study the staggered mining distance of thick coal seams at the same working face,the reasonable reserved width of the coal pillars in the section and the stress distribution law of the coal pillar floor in the upper coal seam section.The research results have been applied to engineering practice and achieved good results.The main research results are as follows:(1)Through the analysis of the height of the caving zone in the mining of the lower thick coal seam,the influence range of the lower coal seam uphill,downhill and strike direction is studied,and the inclination offset distance of the 21201 and 51501 working faces under the same mining conditions is determined to be 50 m.(2)The stress field distribution law of the upper and lower coal seams when the upper and lower coal seams are mined at the same time is studied by using the plasticity theory,the calculation model of the bearing pressure of the upper and lower coal seams is established,and the strike offset distance of the two coal seams during the same mining is determined to be 62 m.(3)The stress distribution model of the coal pillar in the slightly inclined thick coal seam with a large dip angle is established,and the width of the plastic zone and the critical width of the elastic zone of the coal pillar in the section are studied.And the shear stress distribution and transfer law were analyzed numerically with MATLAB,and the reasonable width of the coal pillars in the upper and lower coal seam working face sections was determined.(4)Based on the theoretical research and numerical analysis results,the FLAC3 D numerical simulation model is established.The research on the strike offset distance shows that when the strike offset distance is 62 m,the stress on the first mining face of the upper and lower coal seams does not overlap,and the plastic zones of the roof and floor are not communicated;the research on the trend offset distance shows that when the trend offset distance is 50 m.The coal pillar in the section between the first working face of the upper coal seam is not affected by the caving of the mined goaf at the first working face of the lower coal seam;the research on the stress,displacement and plastic zone under the coal pillar in different sections shows that when the upper coal seam 212 mining area When the coal pillar in the working face section is 20 m,and when the coal pillar in the working face section of the lower coal seam 515 mining area is 34 m,the stability of the section coal pillar is better.(5)The research results were applied in Qifeng Mine.According to the actual situation on the site,the 21203 return air trough mine pressure observation plan was prepared and the mine pressure observation was carried out.The scheme can meet the requirements of engineering practice.