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    深部厚硬顶板群结构演化特征及其诱震机制与防控技术研究

    Structural Evolution, seismogenic mechanisms, and control technologies of deep thick-hard roof strata

    • 摘要: “三高一扰动”是深部煤炭资源开发面临的核心挑战,深部开采静载应力高且地层关键层数多,高静载与岩层断裂动载叠加诱发大能量事件,严重制约了矿井安全高效生产。以营盘壕煤矿2215临空工作面开采过程中频发大能量微震事件为工程背景,为掌握大能量事件发生规律及其分区特征,采用现场微震监测、理论分析与工程实践验证相结合的方法,深入研究厚硬关键层赋存特征及其群结构形态与演变特征,揭示了大能量微震事件的空间分布规律、诱发机制及关键影响因素,提出了“控采速度−巷内爆破−面内爆破”三位一体减震防控策略。结果表明,以8.0×104 J作为大能量微震事件判别阈值,2022年1−7月2215工作面共发生大能量微震事件54次,其中41次位于工作面前方,超前段事件占比达75.93%;双面开采条件下,高位厚硬顶板形成大范围“O”形悬覆结构,低位临空侧顶板形成“S”形或近“L”形非对称悬跨结构,二者共同导致工作面超前40~120 m及临空侧小煤柱附近应力与弹性应变能集中。回采速度突增、突降会引起支承压力迁移速率和顶板破断节奏突变,是大能量微震事件频发的重要诱因;实施控采速度、巷内爆破和面内爆破后,105~106 J事件频次由20次降低至4次,降幅达80.00%,大能量微震事件得到有效控制。

       

      Abstract: The combined effects of high static stress, complex key-strata structures, and mining disturbance pose major challenges to deep coal mining. In deep mining, the superposition of high static stress and dynamic loads induced by strata fracturing can trigger high-energy microseismic events, seriously affecting safe and efficient mine production. Taking the frequent high-energy microseismic events during mining of the No. 2215 goaf-side longwall face in Yingpanhao Coal Mine as the engineering background, field microseismic monitoring, theoretical analysis, and engineering verification were combined to investigate the occurrence characteristics of thick-hard key strata and the morphology and evolution of their grouped structures. The spatial distribution, triggering mechanisms, and key influencing factors of high-energy microseismic events were identified, and an integrated control strategy combining mining-speed control, in-roadway blasting, and in-face blasting was proposed. The results show that 54 high-energy microseismic events, defined using an energy threshold of 8.0×104 J, occurred at the No. 2215 longwall face from January to July 2022, of which 41 occurred ahead of the face, accounting for 75.93%. Under double-face mining conditions, the high-position thick-hard roof formed a large-scale “O”-shaped suspended structure, while the low-position roof on the goaf side formed an “S”-shaped or nearly “L”-shaped asymmetric suspended structure. These structures jointly caused concentrations of stress and elastic strain energy within 40–120 m ahead of the face and near the small coal pillar on the goaf side. Sudden increases or decreases in mining speed altered the migration rate of abutment pressure and the rhythm of roof fracturing, and were important triggers of frequent high-energy microseismic events. After implementing mining-speed control, in-roadway blasting, and in-face blasting, the number of 105–106 J events decreased from 20 to 4, representing a reduction of 80.00%, and high-energy microseismic events were effectively controlled.

       

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