Stability analysis of coal seam floor and coal seam uphill under coal pillar recovery conditions

Tian Xiaolei

doi:10.19896/j.cnki.mtkj.2025.03.013

Abstract：In order to explore the change characteristics of stope stress and the safety of coal pillar recovery under the condition of coal pil-lar recovery,taking the coal pillar recovery of No.9 coal seam in Tongchang Coal Mine as the engineering background,the FLAC3D numeri-cal simulation software was used to analyze the stress distribution characteristics under the mining of upper coal seam(No.9 coal seam)and coal pillar recovery,and the influence degree on the upper coal seam(No.15 coal seam)was analyzed.Combined with field drilling detection technology,the failure depth of No.9 coal seam floor under different conditions was analyzed,and its influence on the uphill of No.15 coal seam was determined.The results showed that the stress distribution on both sides of No.9 coal seam after goaf showed a"W"shape,the stress concentration coefficients at the peak stress position were about 11.34,10.96,and the failure depth of No.9 coal seam floor was about 14.2 m.After the mining of the three uphill protective coal pillars of No.9 coal seam,the vertical stresses of the three up-hill roof of No.15 coal seam were 1.32,1.54 and 1.67 MPa,respectively.The failure depth of the floor of No.9 coal seam was about 23.4 m,and there is still a complete rock layer of about 14.6 m on the uphill roof of the No.15 coal seam.Based on the analysis of the dis-placement state of the surrounding rock,it shows that the deformation of the three uphill surrounding rocks is within a controllable range.