厚硬基本顶综放沿空巷道受载变形机制研究

Study on loading and deformation mechanism of gob-side roadway with thick and hard basic roof in fully mechanized top coal caving workface

针对厚硬基本顶综放沿空巷道回采期间两帮变形剧烈的问题,以柳巷煤矿为工程背景,通过室内试验、现场实测、理论分析和数值模拟等手段,对巷道受载变形机制进行研究。结果表明:1)综放窄煤柱巷道围岩完整度排序由高到低为顶板、实体煤帮及窄煤柱帮,采动影响下煤帮破碎直接导致两帮锚杆工况下降;2)厚硬基本顶整体破断,断裂线位于实体煤上方距采空区14~15 m,关键块回转下沉过程中与上覆岩层之间出现变形不协同,继而导致断裂线附近煤体受载加大,这是采动影响下实体煤帮出现大变形的主要原因;3)随工作面推进窄煤柱发生压剪破坏,压剪断裂线附近煤体破坏严重直接导致窄煤柱帮大变形。

In response to the problem of severe deformation of two sidewalls in gob-side roadway with thick and hard basic roof during the mining of fully mechanized caving face,with Liuxiang Coal Mine as the engineering background,roadway loading and deformation mechanism has been studied systematically through the laboratory test,field monitoring,analytical analysis,and numerical simulation.Results have shown that,1)in terms of the integrity of the rocks in the narrow coal pillar roadway,the rock in the roof is better than that in the solid-sidewall and that in the pillar-sidewall is the worst;bolt working condition of two sidewalls is decreased because of coal wall fracture caused by mining pressure,especially the pillar-sidewall;2)the thick and hard basic roof breaks entirely and its break line is above solid coal,which is 14-15 m far from the goaf.The main reason for large deformation of solid-sidewall under mining pressure is the increased load near the break line,which is caused by the uncoordinated deformation between overlying strata and the key block;3)continuous increase of mining stress causes the compression-shear failure of narrow coal pillar,and then coal body near the compression-shear failure line fractures severely,which is the direct reason for large deformation and fragmentation of pillarsidewall.