长壁孤岛工作面冲击失稳能量场演化规律

煤矿冲击地压一直是困扰中国煤矿安全的主要问题，而煤矿开采过程中跳采形成的孤岛工作面由于容易产生应力集中，来压强度提高，极容易发生冲击地压。基于唐山矿T2193下孤岛工作面的地质条件，从数值分析的角度研究了煤岩体材料的非均匀性，揭示了孤岛工作面顶板周期来压时煤岩体能量释放的动态特征，分析了工作面前方能量释放激增机制。数值模拟结果显示，长壁工作面回采过程中直接顶的不断垮落造成了老顶悬空距离的不断增大，工作面周期来压时，积聚于老顶岩层内的弹性应变能将瞬间释放，容易引发工作面及巷道的冲击失稳。孤岛工作面由于其特有的矿压显现特征，老顶周期破断时所释放的弹性应变能将更加剧烈，冲击地压势必愈加强烈。孤岛工作面顶底板和煤层的能量释放激增可以作为判断煤岩体冲击失稳的前兆信息。孤岛工作面前方发生冲击破坏的主要原因是由于工作面回采过程中围岩所积聚的大量弹性能在顶板断裂时所伴随的巨大能量释放而造成的。

Evolution of energy field instability of island longwall panel during coal bump

Coal bumps have been a major safety concern in underground coal mines in China for more than fifty years. In general, a coal bump refers to a sudden and violent failure of a coal seam that releases contained elastic energy and expels a large amount of coal and rock into the roadway or working face where men and machinery are present. It can cause fatality, injury and significant economic loss for the coal mining industry. Coal bumps occur more frequently in an island longwall panel, which is surrounded by previously mined panels, than in other longwall panels because of its high-stress concentration. In order to investigate the suddenly release of strain energy during extraction of mining face, the nonhomogeneity of materials will be considered to understand the mechanism of energy explosion during periodic weighting of the island longwall panel. Numerical simulations were conducted to study the dynamical character of elastic strain energy relief based on the geological conditions of T2193B island longwall panel in the Tangshan coal mine. Numerical results suggest that the constant collapse of immediate roof will cause continuously increasing of the main roof suspension. Meanwhile, the accumulated elastic strain energy in main roof will abruptly release when the periodic weighting occurs. At this moment, the coal bumps will occur more frequently in the mining face and roadways. It can be revealed that elastic strain energy explosion of main roof and coal seam during periodic weighting is considered to be an important precursor of coal bump occurrence during the extraction of an island longwall panel. Therefore, the significant reason of occurrence of coal bump is the suddenly elastic strain energy explosion during the periodic weighting of man roof. This study of coal bumps in the island longwall panel is of significant importance for coal mine safety and productivity.