Design method for zoning support of overlying inclined coal pillar roadway based on unstable strata thickness

CAO Haigang; CHEN Cong; LI Lifeng; LI Qihang; LI Wei

doi:10.11799/ce202505007

Abstract：Utilizing the 5-2 coal seam working face in the first mining district of Guojiawan Coal Mine as an engineering backdrop,the analysis was conducted on the issue of designing a zonal support method for overlying obliquely intersected coal pillar roadways based on the thickness of unstable strata.Through the application of theoretical analysis,numerical simulations,and on-site engineering practices,the study was conducted to investigate the mechanical structure of surrounding rock and the stability of roadways beneath the remaining obliquely intersected coal pillars.This led to the determination of the principles for designing support zoning and the preferred parameters for the support,both of which were based on the thickness of intact rock strata.Besides,through field engineering practices,a zoning support plan for the roadway was determined and subsequently simulated for verification.The research findings indicated that when conditions such as the mining height and stress concentration factor at the upper coal seam working face changed,the thickness of the unstable rock stratum also varied accordingly,displaying a positive correlation.Among these factors,the stress concentration factor had a relatively significant impact.As the interlayer spacing decreased and approached the centerline of the coal pillar,the stress concentration factor continually increased,while the distance between supports and the effective length of the roof bolt decreased accordingly.In such circumstances,the support scheme was adopted with bolt-cable,full-cable,and shed support successively.The numerical simulation proved to be feasible and practical,and the field verification demonstrated good control effects.This provided a theoretical basis for studying the support issues of roadways located beneath overlying oblique coal pillars.