极近距离煤层下行开采巷道围岩支护技术研究

Research on supporting technology of roadway surrounding rock for downward mining in extreme contiguous seams

为了研究极近距离煤层上煤层开采后应力、采空区对下煤层回采巷道布置及支护效果的影响,采用理论分析、数值模拟和现场实践等方法,根据塑性理论计算采空区底板最大破坏深度及范围,最大破坏深度达9.2 m,破坏范围为20.5 m。通过FLAC^(3D)数值软件模拟分析了极近距离煤层开采底板巷道围岩应力分布规律,得出距离底板不同深度的应力集中程度,以及下位煤层巷道与上方煤柱边缘合理的平面距离。现场巷道为弧顶直墙形,采用“U型钢拱形支架+锚杆索+注浆”联合支护方式。矿压观测结果表明,掘进期间两帮位移量近250 mm,顶板下沉量在80 mm左右,底鼓量约为50 mm。

In order to study the influence of the stress and goaf on the layout and support effect of the mining roadway in the lower coal seam after the mining of the upper coal seam in extreme contiguous seams,using theoretical analysis,numerical simulation and field practice,the maximum failure depth and range of goaf floor were calculated according to the plastic theory.The maximum failure depth was 9.2 m and the failure range was 20.5 m.Through FLAC^(3D) simulation,the stress distribution law of the floor roadway surrounding rock of the extreme contiguous seams mining was analyzed,the stress concentration degree at different depths from the floor,and the reasonable plane distance between the lower coal seam roadway and the edge of the upper coal pillar were obtained.The field roadway was straight wall at the top of the arc,and the combined support method of U-shaped steel arch support+anchor cable+grouting was adopted.The observation results show that the displacement of the two sides is nearly 250 mm,the roof subsidence is about 80 mm,and the floor heave is about 50 mm during the excavation.