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大倾角特厚煤层半煤岩巷道失稳地质动力条件及支护优化

Geo-dynamic conditions instability and support optimization of semi coal-rock roadway in large inclined and extra thick coal seam

  • 摘要: 为明确大倾角特厚煤层半煤岩巷道失稳机制,提高巷道稳定性,以新疆乌东煤矿大倾角特厚煤层分段开采条件下半煤岩巷道为工程背景,利用地质动力区划、统计分析和数值模拟等方法,对乌东煤矿特厚煤层半煤岩巷道地质动力环境及其对巷道稳定性影响进行了研究,并对现有巷道支护方案进行了优化。结果表明:乌东井田主要受清水河子断裂、碗窑沟断裂、白杨南沟断裂等活动断裂影响;对乌东井田内地震活动时序特征和震源深度的统计分析表明,乌东井田尤其是其浅部地质动力活跃度逐年增强,浅部煤岩体能量不断积聚;井下地应力实测表明,巷道走向与最大主应力方向垂直,不利于巷道的稳定性控制。数值分析表明,同煤层上分层开采使巷道围岩应力升高,同水平邻近煤层开采使巷道围岩应力降低;受高水平应力、围岩岩性及煤岩交界弱面的影响,巷道顶底板破坏范围较大,且顶板锚杆和部分锚索处于塑性区内,导致锚固作用不能充分发挥;巷道顶板积聚大量弹性能,易诱发顶板动力灾害。在此基础上,针对巷道支护现状,提出了增加锚杆长度、提高锚杆预应力、采用全长锚固、调整锚索角度、改进护表材料以及采用全长锚固锚杆对巷道底板和底角进行加固等方法和措施,以期提高巷道稳定性,为类似条件巷道的支护提供有益借鉴。

     

    Abstract: In order to clarify the instability mechanism of semi coal rock roadway in highly inclined and extra thick coal seam and improve the stability of roadway, taking the semi coal rock roadway in the highly inclined and extra thick coal seams of Wudong Coal Mine in Xinjiang as the engineering background, the geo-dynamic environment of semi coal-rock roadway in Wudong coal mine and its influence on the roadway stability were studied with comprehensive methods including geo-dynamic division, statistical analysis and numerical simulation, etc. The existing roadway support scheme was optimized. The results show that Wudong coal mine is mainly affected by Qingshuihezi fault, Wanyaogou fault, Baiyangnangou fault and other active faults. The statistical analysis of the time sequence characteristics of seismic activity and focal depth in Wudong Minefield shows that the geodynamic activity of Wudong minefield, especially its shallow part, is increasing year by year, and the energy of the shallow coal and rock mass is continuously accumulating; the underground in-situ stress measurement shows that the direction of the roadway is perpendicular to the maximum principal stress, which is unfavorable to the roadway stability. The numerical analysis shows that the surrounding rock stress increases with the mining of the upper panels in the same coal seam and contrarily it decreases with the mining of the adjacent panel at the same level. Affected by high level stress, surrounding rock lithology and weak surface of coal rock interface, the roof and floor of the roadway are damaged in a large range, and roof bolts and some anchor cables are in the plastic zone, resulting in insufficient anchoring. The energy accumulated in the roof will lead to dynamic disaster easily. On this basis, according to the current situation of roadway support, the methods and measures such as increasing the length of anchor bolt, increasing the pre-stress of anchor bolt, adopting full length anchoring, adjusting the angle of anchor cable, improving the surface protection materials, and using full length anchoring anchor bolt to reinforce the floor and bottom angle of roadway are proposed so as to,improve the stability of the roadway, and provide a useful reference for roadway support under similar conditions.

     

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