长壁孤岛工作面冲击失稳能量释放激增机制研究

煤矿开采中跳采形成的孤岛工作面由于容易产生应力集中，来压强度高，极容易发生冲击地压。基于唐山矿孤岛工作面的地质条件和周期来压步距的监测结果，通过数值分析的方法，研究孤岛工作面煤岩体能量释放的动态特征，揭示工作面前方能量释放激增机制，对比普通工作面和孤岛工作面能量场的区别，介绍冲击地压预警防治措施。数值模拟结果显示，长壁孤岛工作面回采时随着直接顶的随采随冒，采空区悬空面积的不断增大，使得老顶积聚大量的弹性能。若老顶发生周期性垮落，弹性能将瞬间释放，此时工作面和顺槽巷道极易冲击失稳。由研究结果可知，孤岛工作面周期来压时顶底板和煤层的能量激增可做为判断冲击失稳的前兆信息之一。因此，微震监测等手段可以根据此结论预测潜在的矿山动力灾害。针对老顶周期性断裂时积聚能量的突然释放规律，运用强制放顶、超前卸压孔、开切卸压槽和卸压爆破、煤层注水等技术可以提前释放煤层内积聚的弹性能，达到良好的冲击地压防治效果。

INVESTIGATION ON MECHANISM OF ENERGY EXPLOSION DURING EXTRACTION OF ISLAND LONGWALL PANEL

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. 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. Based on the geological conditions of island longwall panel in the Tangshan coal mine in Tangshan，China，numerical simulations were conducted to investigate the dynamical character of elastic strain energy relief and to understand the mechanism of energy explosion during periodic weighting of the island longwall panel. The advance of mining will cause continuously increasing of the goaf space because of the constant collapse of immediate roof. The accumulated elastic strain energy in main roof will abruptly release when the periodic weighting occurs. At this moment，the coal bumps occur more frequently. Numerical results suggest 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，it can be revealed that the one of significant reason of occurrence of coal bump is the suddenly elastic strain energy explosion during the periodic weighting of main roof. Based on these analyses，microseismic observation can be chosen to forecast the occurrence of coal bumps. Additionally，technology of forced roof caving and stress relief in coal seam is effective method to prevent the coal bump of island longwall panel.