极近距离煤层开采无煤柱自成巷控制方法研究

Research on control methods of automatically-formed roadway without coal pillar for extremely close-distance coal seams

极近距离煤层传统长壁开采,受上层遗留煤柱和采空区垮落等因素的影响,下煤层开采过程中应力环境复杂、矿压显现剧烈,易诱发巷道围岩大变形。为解决上述问题,提出了极近距离条件下巷道定向切顶–约束高强支护无煤柱自成巷控制方法。通过顶板定向预裂切顶,主动改变顶板悬臂结构,切断采空区向巷道顶板的应力传递。充分利用矿山压力和岩体碎胀特性,取消煤柱留设,结合高强支护加强巷道顶板整体性,共同实现切顶自成巷。建立了极近距离煤层开采覆岩结构模型,计算了下煤层切顶自成巷巷旁支护阻力。以典型极近距离煤层为工程背景,开展了不同开采方法的数值试验对比研究,结果表明,提出的自成巷控制方法使巷道围岩应力降低59.8%,巷道顶板变形减少70.8%,并明确了极近距离煤层开采无煤柱自成巷控制机理。在此基础上,开展了典型极近距离煤层工程设计及现场应用研究,结果表明该方法有效降低了矿压显现程度,保证了自成巷的安全稳定控制。

The traditional longwall mining of extremely close-distance coal seams is affected by remaining coal pillars and collapse of the goaf.During the mining process of lower working face,the stress environment is com-plex and the mining pressure is severe,inducing large deformation of roadway.To solve the problems above,we proposed a control method for directional roof cutting and constrained high-strength support of automatically-formed roadway(AFR)without coal pillars under extremely close-distance conditions.By directional pre-splitting of the roof,the long cantilever structure of roof is actively changed and the stress transfer from the goaf to the roadway roof is cut off.The crushing and swelling characteristics of rock mass are fully utilized,the high-strength support is combined to strengthen the integrity of roadway roof,and jointly realize the AFR without coal pillars.A model of overlying rock structure for extremely close-distance coal seam mining is established,and the support resistance of the automatically-formed roadway on the roof of the lower coal seam is calculated.Taking typical extremely-close coal seams as the engineering background,the numerical experiments were conducted to compare different mining methods.The results show that the stress of the roadway surrounding rock decreased by 59.8%,and the deformation of the roadway roof decreased by 70.8%.The control mechanism of the automatically-formed roadway without coal pillars in extremely close-distance coal seam mining was clarified.On this basis,we have conducted research on the design andsite application of typical extremely-close-distance coal seam engineer-ing.The results show that the method effectively reduced the occurrence of mine pressure and ensured the safe and stable control of the automatically-formed roadway.