近水平厚煤层小煤柱沿空巷道帮部塌孔机理及控制技术研究

Sidewall hole collapse mechanism and control technology of narrow coal pillar goaf roadway in near−horizontal thick coal seam

  • 摘要: 我国西部侏罗系近水平厚煤层小煤柱沿空掘巷,普遍存在围岩破碎、帮部变形剧烈及锚杆施工塌孔严重等难题。以门克庆煤矿2104工作面回风巷为工程背景,采用现场调研、矿压监测、数值模拟与工程试验相结合的方法,系统研究沿空巷道围岩应力演化、变形破坏特征及帮部塌孔链式演化机理,并针对性研发钻锚一体式中空注浆锚杆一体化围岩控制技术。结果表明:邻近采空区形成非对称应力场,掘进扰动导致帮部浅部围岩大范围卸荷损伤及塑性破碎带发育;超前支承压力峰值先升后降,应力降低区持续扩展,钻孔扰动诱发孔壁坍塌,形成“破碎−塌孔−支护失效−变形加剧”的恶性循环。煤层强度低、节理发育及直接顶易风化是塌孔的地质基础,非对称矿压、帮部高应力集中与塑性区贯通是其力学根源。提出钻锚一体式中空注浆锚杆一体化支护技术并开展工业试验,现场应用表明:单根锚杆平均施工时间由13.16 min降至5.6 min,效率提升2.35倍,帮部累计变形降低78.8%,有效阻断塌孔与围岩失稳的连锁反应,锚固质量与掘进连续性显著改善。研究成果可为同类近水平厚煤层沿空巷道围岩塌孔防控与稳定控制提供理论依据与工程参考。

     

    Abstract: Severe challenges including fractured surrounding rock, intense sidewall deformation and frequent hole collapse during bolt installation commonly exist in gob−side entry driving with small coal pillars in nearly horizontal thick Jurassic coal seams in western China. Taking the return airway of Panel 2104 in Menkeqing Coal Mine as the engineering background, field investigation, mine pressure monitoring, numerical simulation and field engineering tests were combined to systematically investigate the stress evolution, deformation and failure characteristics of surrounding rock in the gob−side entry, as well as the chain evolution mechanism of sidewall hole collapse. Targetedly, an integrated surrounding rock control technology adopting drilling−bolting integrated hollow grouting bolts was developed. The results reveal that an asymmetric stress field forms adjacent to the goaf, and excavation disturbance triggers extensive unloading damage of shallow sidewall surrounding rock and the development of plastic fracture zones. The peak advance abutment pressure rises first and then declines, accompanied by continuous expansion of the stress relief zone. Disturbance induced by borehole drilling causes borehole wall collapse, generating a vicious cycle of“fracture−hole collapse−support failure−aggravated deformation”.Low coal seam strength, developed joints and weather−prone immediate roof constitute the geological prerequisites for hole collapse, while asymmetric mine pressure, high stress concentration in sidewalls and connected plastic zones act as its mechanical origins. The integrated support technology using drilling−bolting integrated hollow grouting bolts is proposed and verified via industrial field tests. Field application demonstrates that the average installation time for a single bolt is reduced from 13.16 min to 5.6 min, representing a 2.35−fold improvement in construction efficiency; cumulative sidewall deformation decreases by 78.8%. This technology effectively breaks the chain reaction between hole collapse and surrounding rock instability, and greatly improves anchorage quality and continuous excavation performance. The research findings can provide theoretical support and engineering references for hole collapse prevention and stability control of gob−side entries in similar nearly horizontal thick coal seams.

     

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