软弱夹层巷道围岩失稳特征分析及控制技术研究

Analysis of Surrounding Rock Instability Characteristics and Control Technology of Weak Interlayer Roadway

为研究软弱夹层对煤矿巷道围岩失稳破坏的影响,基于3DEC离散元模拟软件,建立了不同工况条件下含弱层煤矿巷道数值计算模型,提出割底岩掘进方案,并对不同工况条件下方案进行对比分析及对软弱夹层作用下巷道围岩失稳破坏规律展开研究。结果表明:巷道变形特征与巷道在煤层中布置方式、煤层顶底板围岩强度有关,夹矸层在煤层中不同层位对巷道变形破坏影响也不同。弱层的存在改变了围岩中应力传递路径,软弱夹层与上下相对坚硬岩石交界层面处,因摩擦约束应力作用,导致夹层处的水平应力减小,从而该处位置的强度随之下降,夹层丧失承载能力发生破坏,进而加剧围岩的剪切破坏与水平滑移。通过不同工况方案对比,得出巷道掘进过程中控制割岩层位,夹层置于煤层底板下0.3 m工况方案满足要求。

For the study of weak intercalation effect on the instability of surrounding rock in coal mine,based on 3DEC discrete element simulation software,different working conditions,established the numerical calculation model with weak layer under the condition of coal roadway,cut bottom rock excavation scheme is put forward,and the solutions were analyzed under different working conditions and instability of surrounding rock under the action of the weak intercalated law study.The results show that the deformation characteristics of roadway are related to the layout of roadway in coal seam and the strength of surrounding rock on the roof and floor of coal seam.The existence of the weak layer change the stress paths in the surrounding rock,weak intercalated with relatively hard rock border level,up and down due to friction constraint stress,leading to the level of stress of the sandwich is reduced,thereby the position there strength drops,interlayer damage loss of bearing capacity,thereby deepening of shear failure of surrounding rock and horizontal slip.Through the comparison of schemes under different working conditions,it is concluded that the working scheme of controlling cutting strata position and placing interlayer O.3 m under coal seam floor meets the requirements in the course of roadway excavation.