煤层巷道围岩“闷炮”声现象发生机理研究

    Research on generation mechanism of “muffled blast” sound phenomenon in surrounding rock of coal seam roadways

    • 摘要: 我国中部地区部分矿井在煤炭开采过程中伴随着频繁的“闷炮”声现象,表征存储能量的骤然迸发,对矿井安全生产构成了潜在威胁。为研究煤层巷道围岩“闷炮”声发生机理,以阳胜煤业15号煤层为工程背景,通过微震监测定位“闷炮”声源头,实地采样后对煤岩体进行力学试验和声发射监测,并通过真实破裂过程分析(RFPA)软件数值模拟以及现场实测进行综合分析。结果表明:顶板灰岩层脆性高、强度低,裂隙较为发育,在应力扰动或高位岩层周期性应力集中作用下巷道围岩产生裂隙扩展,产生大量声发射信号;巷道围岩破坏以剪切破坏为主,声发射信号主要集中在巷道两帮15 m、顶板10 m范围之内,且大部分在帮顶角附近积聚;巷道变形破坏过程中,在声发射信号集中的范围内积聚了大量的弹性能,当弹性能释放时就会产生“闷炮”声现象,证明了“闷炮”声现象主要由围岩变形破坏时能量瞬间释放引起,并非冲击地压的前兆。

       

      Abstract: Frequent “muffled blast” sounds accompany coal mining in some coal mines in central China, which characterize the sudden release of stored energy and pose a potential threat to the safe production of coal mines. To investigate the generation mechanism of “muffled blast” sounds in the surrounding rock of coal seam roadways, taking the No.15 coal seam of Yangsheng Coal Industry as the engineering background, the sources of “muffled blast” sounds were located via micro-seismic monitoring. After on-site sampling, mechanical tests and acoustic emission monitoring were carried out on coal and rock masses, and a comprehensive analysis was conducted through numerical simulation with the real failure process analysis (RFPA) software combined with field measurements. The results show that the limestone roof stratum has high brittleness, low strength and well-developed fractures. Under the action of stress disturbance or periodic stress concentration in high-position strata, fracture propagation occurs in the surrounding rock of roadways, generating a large number of acoustic emission signals. The failure of roadway surrounding rock is dominated by shear failure, and the acoustic emission signals are mainly concentrated within the range of 15 m in the two ribs and 10 m in the roof of the roadway, with most accumulating near the rib-roof corners. During the deformation and failure process of the roadway, a large amount of elastic energy accumulates in the area where acoustic emission signals concentrate, and the release of this elastic energy gives rise to the “muffled blast” phenomenon. This verifies that the “muffled blast” phenomenon is mainly caused by the instantaneous release of energy during the deformation and failure of surrounding rock, and is not a precursor of rock burst.

       

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