Analysis of coal pillar rock burst appearance in multi-seam mining with thick and hard roof
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摘要: 现有研究只是针对特定条件下的冲击显现特征进行分析，缺乏对厚硬顶板条件下煤柱诱发冲击显现的研究。针对该问题，以新疆某矿I010203工作面为研究对象，采用现场监测、数值模拟手段，分析了厚硬顶板多煤层开采条件下的工作面冲击显现特征及原因。通过分析现场监测的微震大能量事件空间分布规律、支架压力分布特征，以及数值模拟的工作面回采期间围岩应力分布特征，得出结论：工作面运输巷区域应力集中程度和微震事件密集程度均高于回风巷区域，顶板与煤层区域应力集中程度与微震事件密集程度大于底板区域。基于上述结果，采用动静载叠加诱冲理论分析了I010203工作面开采过程中煤柱型冲击显现原因：① 运输巷区段煤柱上方易产生侧向悬顶，长悬顶突然破断并产生大量动载荷，同时在开采过程中煤柱和顶板积聚了大量静载荷，当两者叠加超过临界载荷时可能造成工作面冲击显现或大能量事件；I010203工作面回采过程中受煤柱集中应力、上覆顶板及围岩支承应力等主控因素影响，易产生煤柱型、厚硬顶板垮落型冲击显现。② 当工作面回采位置逐渐接近"刀把形"采空区边界时，边界应力向下传递至I010203工作面，从而导致I010203工作面冲击危险性进一步增大。Abstract: The existing research only analyzes the rock burst appearance characteristics under specific conditions, lacks research on the rock burst appearance induced by coal pillar under the condition of thick and hard roof. In order to solve this problem, taking I010203 working face of a mine in Xinjiang as the research object, the paper analyzes the characteristics and causes of working face rock burst under the condition of thick and hard roof multi-seam mining by means of field monitoring and numerical simulation. By analyzing the spatial distribution law of microseismic and large energy events monitored on site, the distribution characteristics of support pressure, and the distribution characteristics of surrounding rock stress during the mining of the working face simulated by numerical simulation, this paper obtained the following results. The stress concentration and the microseismic event density in the transport roadway area of the working face are higher than those in the return air roadway area. And the stress concentration and microseismic event density in the roof and coal seam area are higher than those in the floor area. Based on the above results, the causes of coal pillar rock burst appearance in the mining process of I010203 working face are analyzed by using rock burst caused by dynamic and static combined load theory. ① It is easy to produce lateral overhanging roof above the coal pillar in the transport roadway section. The sudden breaking of the long overhanging roof generates a large amount of dynamic loads. At the same time, a large amount of static loads accumulate on the coal pillars and the roof during the mining process. When the superposition of the two exceeds the critical load, it may cause the rock burst appearance of the working face or a large energy event. The mining process of the I010203 working face mainly includes the main controlling factors such as coal pillar concentrated stress, overlying roof and surrounding rock supporting stress. Therefore, it is easy to produce coal pillar type and thick hard roof caving type rock burst appearance. ② When the mining position of the working face gradually approaches the boundary of the ‘knife shape’ goaf, the boundary stress is transferred downward to the I010203 working face, which leads to the further increase of the rock burst risk of the I010203 working face.
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