深井沿空切顶巷道围岩协同控制及应力演化规律

Coordination control and stress evolution of surrounding rock of gob-side entryretaining cutting roof in deep mine

为解决深部沿空留巷动压显著﹑难支护的问题,基于切顶沿空留巷技术原理,对深部沿空切顶巷道卸压效果﹑围岩应力演化规律及控制技术进行深入研究。超前顶板切缝切断了采空区顶板向留巷顶板传递应力的路径,避免了采掘应力叠加,消除了工作面端头与回采巷道交叉口的"应力尖角";切缝可使一定范围内工作面支架平均压力和周期压力减小,随着远离切缝,影响逐渐消失;直接顶悬臂梁长度的减小和基本顶有效荷载的降低是导致支架平均压力和周期压力下降的主要原因。根据深部地质力学环境及岩体变形特征,构建"恒阻主动让压控制顶板、柔性可缩让位抗侧压、高阻临时支护抗动压,加大支护长度护煤帮"的深井沿空切顶巷道围岩协同控制体系,并在城郊煤矿21304工作面进行现场试验。结果显示:构建的协同控制体系能有效控制深部岩体变形,取得较好的应用效果。

In order to solve the problems of the increased dynamic pressure in deep gob-side entry-retaining and the difficulty in supporting the roadway,the effect of pressure relief,the stress evolution law and control technology of surrounding rock are studied in depth based on the technical principle of gob-side entry retaining cutting roof.The kerf of leading roof cuts the path through which the stress is transmitted from the roof of goaf to that of the reserved tunnel,avoiding the superposition of the mining stress and eliminating the"stress cusp"at the intersection of the working face and the mining roadway.The average pressure and periodic pressure of the bracket in the working face can be reduced by the kerf and gradually disappear with the increased distance from the kerf.And that is mainly due to the reduction of the length of direct overhead cantilever beam and the effective load of the basic roof.According to the deep geomechanical environment and the deformation characteristics of rock mass,the collaborative control system of surrounding rock of deep gob-side entry-retaining cutting roof of"Constant resistance to allow pressure to control the roof,flexible retractable place to resist lateral pressure,high resistance temporary support against dynamic pressure,and increase support length to protect coal sidewall"are constructed and the field test is carried out in working face 21304 of suburban coal mine.The results have shown that the collaborative control system can effectively control the deformation of the deep rock mass and has been well applied.