两侧不规则采空区孤岛工作面煤体整体冲击失稳研究

RESEARCH ON COAL OVERALL INSTABILITY OF ISOLATED WORKING FACE WITH IRREGULAR GOBS ON BOTH SIDES

为了研究两侧不规则采空区孤岛工作面煤体整体冲击失稳的危险性,以山东某矿3206孤岛工作面为工程背景,分析工作面回采期间两侧不规则采空区顶板结构动态变化过程;采用高精度微震监测技术,获得该矿采空区上覆岩层移动角和触矸角;提出孤岛工作面煤体支承压力计算公式及失稳分析方法,分析得出孤岛工作面侧向采空区由悬顶向半悬顶结构转变时应力达到最大、而采空区宽度足够大(进入充分采动阶段)时应力反而减小的结论。最后,结合3206工作面地质条件得到工作面回采期间各阶段的失稳系数。分析结果表明:该工作面在回采过程中,发生冲击失稳的可能性较大,但通过采取大直径钻孔卸压等防冲措施,该工作面可以安全回采,开采实践证明,本文结论是正确的。

To research the risk of coal overall instability of isolated working face with irregular gobs on both sides,the isolated working face 3206 of a mine in Shandong as the engineering background was studied,and the dynamic process of roof structure in irregular gobs on both sides during the period of mining working face was analyzed in this paper. Based on the technique of microseismic monitoring with high accuracy,the amount of overburden movement angle and gangue contacting angle over the gobs was got. Meanwhile,the calculative formula of bearing pressure on isolated working face of coal and the analytic method of its instability was proposed. The results showed that stress would reach a maximum when the hanging roof structure turned to the semi-hanging roof structure over gobs,while stress would reduce when the width of gobs was large enough which indicated the gobs had came into a full-mining level. Moreover,the instability coefficient in various stages was obtained during the mining based on the geological conditions of the working face 3206. The analysis results showed that: the instability would occur quite possibly when the working face was in the process of mining. However,it could be mined safely by taking the method of drilling relief with large diameter to prevent the occurrence of rock burst. Ultimately,the correctness of this paper has been confirmed by the mining practice.