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锯齿煤柱非对称孤岛工作面冲击地压机理及防治研究

Research on the mechanism and prevention of rock burst in asymmetrical isolated working faces with sawtooth coal pillars

  • 摘要: 针对非对称孤岛工作面面临的采场高应力、高冲击风险等现象,以某矿孤岛工作面为背景,采用理论分析、数值模拟、现场实践等方法研究了非对称孤岛工作面覆岩结构演化特征,厘清了非对称约束下孤岛工作面支承压力的变化规律,揭示了锯齿煤柱非对称孤岛工作面冲击地压机理,并提出了针对性的协同卸压减冲方案。结果表明,当煤柱W1≤36.5m时,覆岩为非对称“T”结构;当煤柱宽度W1>36.5m时,覆岩为长臂“F”结构;工作面支承压力由材料顺槽侧向运输顺槽一侧倾斜呈“双峰型”分布;当煤柱宽度W1由20m增加至170m时,运输、材料顺槽的端头应力峰值分别增幅5.9%、8.5%,应力集中系数峰值分别为2.20、3.05;工作面端头应力集中程度和范围增加且关键层破断释放的强动载,易诱发工作面冲击地压。制定了顶板预裂爆破、煤体大直径钻孔动态卸压防冲方案,施工后工作面微震活动强度、能量密度显著降低,降低了工作面的冲击风险。研究结论可为类似条件的孤岛工作面开采提供借鉴。

     

    Abstract: Addressing phenomena such as high stress and high impact risk in asymmetric isolated longwall faces, this study, based on a certain mine's isolated longwall face, employed theoretical analysis, numerical simulation and field practice to investigate the evolution characteristics of the overlying strata in asymmetric isolated longwall faces, clarified the variation law of support pressure under asymmetric constraints, revealed the rockburst mechanism of jagged coal pillar asymmetric isolated longwall faces, and proposed targeted collaborative pressure-relief measures to reduce impact. The results show that when the coal pillar width W1≤36.5m, the overlying strata form an asymmetric "T" structure; when W1>36.5m, the overlying strata form a long-arm "F" structure; support pressure on the face displays an inclined "double-peak" distribution from the material gate side to the return gate side; when W1 increases from 20m to 170m, the peak stress at the ends of the transport and material gates increases by 5.9% and 8.5% respectively, with stress concentration coefficient peaks of 2.20 and 3.05; the degree and range of end stress concentration increase and the strong dynamic load released due to the key layer fracture easily trigger rockbursts on the face. A pre-split roof blasting and large-diameter borehole dynamic pressure-relief scheme was developed to prevent impact, and after construction, microseismic activity intensity and energy density on the face were significantly reduced, lowering the risk of rockburst. The research conclusions can provide reference for the mining of isolated longwall faces under similar conditions.

     

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