巨厚砾岩下回采巷道冲击破坏机理

Impact failure mechanism of mining roadway under ultra-thick conglomerate

为探究巨厚砾岩下回采巷道冲击破坏机理,以千秋煤矿21141工作面(半孤岛面)运输巷为工程背景,首先采用数值模拟手段分析正常工作面和半孤岛面主应力场特征和回采巷道围岩区域主应力场特征,以及顶板破断产生的扰动作用对巷道围岩塑性区的影响。结果显示半孤岛开采引起的最大主应力较大,巷道围岩塑性区呈蝶形分布且在煤层中出现急剧扩展。然后分析巷道围岩蝶形塑性区急剧扩展的力学机制,得出巷道RPP曲线,阐述巷道冲击破坏的敏感因素,并揭示巨厚砾岩下回采巷道冲击破坏机理:处于半孤岛面中部的回采巷道在受到顶板破断产生的扰动作用后,巷道围岩区域主应力场突然发生改变,导致围岩蝶形塑性区急剧扩展,并以声响、震动和煤岩体抛出的形式释放存储于体内和围岩系统中的大量弹性能,出现爆炸式破坏的动力现象。

In order to explore the burst failure mechanism of the mining roadway under ultra-thick conglomerate, with working face 21141(semi-island) transportation roadway in Qianqiu coal mine as the engineering background, the numerical simulation method is applied to analyze the characteristics of principle stress field of normal and semi-island working face and that of the regions in the surrounding rock as well as the impact of the disturbance of roof breaking on plastic zone of the surrounding rock.The results have shown that maximum principle stress caused by semi-island mining is large, and that the plastic zone of the surrounding rock is butterfly-shaped and tends to expand sharply in coal seam.And then, through analyzing the mechanical mechanism about sharp expansion of butterfly-shaped plastic zone in the surrounding rock, RPP curves of the roadway are obtained;sensitive factors of burst failure are stated;the burst failure mechanism in the mining roadway under ultra-thick conglomerate is revealed accordingly. Because of the disturbance of roof breaking, the regional principle stress field of the surrounding rock in the mining roadway changes suddenly, which causes the sharp expansion of butterfly-shaped plastic zone, and releases plenty of elastic energy stored in the coal body and surrounding rock system in the form of sound, vibration and coal or rock mass burst, resulting in the dynamic phenomenon of explosive failure.