Layout optimization of mining roadway in contiguous extra-thick coal seams
In view of the technical problems of roadway layout in the extra-thick coal seam with residual coal pillars after contiguous coal seams mining,we took Tangshan Coal Mine as the research object,and studied the failure depth of the floor after mining in the upper coal seam,the stress distribution of the floor of the residual coal pillar and the reasons for the failure of the roadway roof in the lower seam under the uneven load,using theoretical analysis,numerical simulation and field measurement.The research shows that,the maximum failure depth caused by the abutment stress leaded by the upper coal seam mining is 31.5 m,which affects roadway arrangement in the lower seam.Vertical stress of the coal pillar floor has distributes in an obvious non-uniform manner and the lower coal seam mining roadway is more likely to reach the tensile limit which leads to deformation damage.The characteristics of the main stress distribution under four types of roadway arrangement in the lower coal seam were also compared and the inner-staggered and translational arrangements were preferred.Furthermore,the unbalanced degree of stress and deformation of the roof of the mining roadway was evaluated by combining the stress change Δσ and displacement change ΔD of the roadway.Combining with the numerical simulation and field industrial test data,the optimal inner stagger distance of the mining roadway in the working face of 9 coal seam is 37.5 m,which provides a reference for the layout of the extra-thick coal seam mining roadway.
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