Study on the mechanism and application of support reinforcement for narrow coal pillars under high-pressure disturbances in deep mining

LI Ang; LYU Luna; ZHOU Yonggen; YU Zhenzi; WANG Man; FENG Feng; HAN Tairan; CHENG Xun

doi:10.13247/j.cnki.jcumt.20240406

Abstract：To address the deformation and failure of surrounding rock in gob-side entry retaining within deep,high-stress,and weak coal seam environments,a combined approach of theoretical analysis,laboratory-scale physical simulation,and field testing was adopted.The mechanical response and deformation behavior of the narrow coal pillar and solid coal were systematically studied,and an optimized support scheme suitable for actual engineering conditions was proposed.A mechanical model of the narrow coal pillar's sidewall was established,and analytical solutions for stress and displacement were derived.The analysis indicated that the stability of the narrow coal pillar was significantly influenced by support resistance and roof subsidence.A prefabricated support model for anchor-net-cable reinforcement was independently developed for use in physical simulations,and optimization-based tests were conducted to analyze the displacement and deformation evolution of the gob-side entry surrounding rock using digital image technology.Field monitoring further verified the reliability of the optimized support scheme.The study revealed the following findings:The stability of the narrow coal pillar is predominantly affected by support resistance and roof subsidence.The calculated plastic zone widths on the side adjacent to the entry and the solid coal side are 2.11 and 0.60 m,respectively,with maximum displacements of 1.00 and 0.62 m.The original 2.6 m rock bolt support system is ineffective for reinforcing the narrow coal pillar.Deformation of the coal pillar sidewall exhibites significant sensitivity to changes in support resistance,showing an inverse relationship.Increasing support resistance effectively restrictes deformation.Field monitoring demonstrated that,after applying the optimized support scheme,the maximum convergence of the coal pillar sidewall and solid coal sidewall decreases to 0.81 and 0.38 m,respectively,while the maximum roof subsidence is limited to 0.70 m.The reinforcement anchor cables and timber posts in the entry center effectively stabilizes the sidewalls and roof,significantly controlling surrounding rock deformation.During the initial stages of entry excavation,anchor cable forces increase gradually,accelerating under multiple stress disturbances from mining activities.However,the maximum axial force of the sidewall anchor cables remaines below their ultimate tensile load,confirming the safety margin of the support system.