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遗留煤柱下工作面回采强矿压致灾机理及防治技术研究

Research on the mechanism and prevention techniques for strong rock pressure-induced disasters in coal mining under coal pillars

  • 摘要: 针对浅埋近距离煤层过上覆遗留煤柱时易诱发强矿压动力灾害难题,以南梁煤矿30210工作面为工程背景,综合应用理论分析、数值模拟、物理模拟和现场实测相结合的方法,系统研究了遗留煤柱下开采工作面矿压规律,揭示了强矿压灾害发生机理,并提出了“空间分区-力学协同”的定向钻孔水力压裂超前区域弱化防治技术。研究表明:工作面出煤柱阶段,煤柱及上覆关键承载结构受开采扰动突发失稳,积聚的弹性能以动能形式瞬间释放至采场,易诱发强矿压灾害。基于“压裂垮落体支承-立体分区关键岩层弱化-应力传递路径转移”防控思路,构建了空间分区力学协同的水力压裂技术体系,并通过物理模拟验证了其有效性。通过构建人工裂缝网络,使煤柱集中应力驱动的间隔岩层提前破断、覆岩载荷向后方垮落岩体转移,实现了应力路径重构,周期来压步距缩短至8~16 m,超前支承压力峰值下降至9.26 MPa以下。现场压裂结果表明,压裂压力曲线呈“锯齿状”波动,裂缝起裂瞬间压力突降1.5~6.0 MPa,揭示了能量从“瞬时冲击释放”向“分阶段缓释”的分级释放机制。治理后来压步距较治理前的18 m缩短至8~13 m,峰值压力与平均阻力分别下降18%和22%,工作面推进过程中未发生强矿压,实现了“应力-结构-能量”的协同调控。

     

    Abstract: Addressing the challenge of inducing strong mining pressure dynamic disasters when mining shallowly buried, close-proximity coal seams overlying residual coal pillars, this study uses the 30210 working face at Nanliang Coal Mine as its engineering context. This study employs a combined approach of theoretical analysis, numerical simulation, physical modeling, and field measurements to investigate the rock pressure patterns in the mining face beneath the residual coal pillar. It reveals the mechanisms underlying severe rock pressure disasters and proposes a “spatial zoning-mechanical coordination” technique for advance zone weakening through directional drilling and hydraulic fracturing. The study indicates that during coal pillar extraction, the pillar and its overlying critical load-bearing structures undergo sudden instability due to mining disturbance. Accumulated elastic energy is instantaneously released as kinetic energy into the mining area, readily triggering severe rock pressure disasters. Based on the prevention strategy of “fracturing collapse support - three-dimensional zoned weakening of key strata - stress transfer path diversion,” a hydraulic fracturing technology system for spatial zoned synergistic weakening was established and validated through physical simulation. By creating an artificial fracture network, the system induces premature failure of the coal pillar's stress-concentrated interlayer strata and redirects overburden loads toward the rear collapse mass. This reconfigures stress pathways, reducing cyclic pressure advance intervals to 8-16 m and lowering peak advance support pressure to below 9.26 MPa. The field fracturing results show that the fracturing pressure curve fluctuates in a ' serrated ' manner, and the pressure drops sharply by 1.5-6 MPa at the moment of fracture initiation. The hierarchical release mechanism of energy from ' instantaneous impact release ' to ' staged slow release ' was constructed. After the treatment, the pressure step distance was shortened to 8 ~ 13 m from 18 m before the treatment, and the peak pressure and average resistance decreased by 18% and 22% respectively. There was no strong rock pressure in the process of working face advancing, and the coordinated control of ' stress structure energy ' was realized.

     

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