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冲沟下浅埋煤层开采突水主控因素分析与风险评估

Analysis and risk assessment of main controlling factors of water inrush in shallow buried coal seam mining under gully

  • 摘要: 为研究冲沟水体下浅埋煤层开采易发生矿井突水的问题,以鄂尔多斯某煤矿22104工作面为工程背景,采用裂隙导通理论模型、瞬变电磁仪测量和PFC数值模拟,对矿井突水致灾主控因素与风险评估方法展开了研究。结果表明:突水裂隙无法导通的充要条件为冲沟下行裂隙和裂隙带上行裂隙的最大垂向发育长度之和(Ha+Hb)不超过二者的垂直间距(H),二者最大发育宽度之和(da+db)不超过二者水平间距(d);影响地表水渗漏、突水至工作面的主控因素为工作面开采高度(M),工作面与冲沟的空间相对位置(垂直间距H、水平间距d)和冲沟产状(冲沟倾角β、冲沟深度Hd和冲沟宽度L);采高通过控制裂隙带发育范围和冲沟边坡弯曲幅度直接影响突水裂隙通道的形成;工作面与冲沟的相对位置通过限制裂隙带上行裂隙与冲沟下行裂隙的间隔距离控制突水裂隙的连接;冲沟产状通过调控边坡变形程度,改变冲沟下行裂隙开口大小间接影响突水裂隙通道形成。基于上述结论,结合模糊数学方法、层次分析法和灾害指数法建立了冲沟水体下浅埋煤层开采突水风险评估模型,计算分析了22014工作面突水危险区域和灾害指数,提出了工作面局部充填方案,现场应用结果表明,相比于初始开采未充填区域,充填区域的顶板涌水明显减小,实现了冲沟水体下浅埋煤层安全高效开采。

     

    Abstract: To investigate the problem of mine water inrush in shallow coal seam mining under gully water body, taking 22104 working face of a coal mine in Ordos as the engineering background, the main controlling factors and risk assessment methods of mine water inrush were studied by using fracture conduction theory model, transient electromagnetic instrument measurement and PFC numerical simulation. The results show that the necessary and sufficient condition for the failure of water inrush fracture is that the sum of the maximum vertical development length (Ha+Hb) of the downward fracture of the gully and the upward fracture of the fracture zone does not exceed their vertical spacing (H), and the sum of the maximum development widths of the two (da+db) does not exceed their horizontal spacing (d). The main controlling factors affecting surface water leakage and water inrush to the working face are the mining height of the working face (M), the spatial relative position of the working face and the gully (vertical spacing H, horizontal spacing d) and the gully occurrence (gully dip angle β, gully depth Hd and gully width L). The mining height directly affects the formation of water inrush fracture channel by controlling the development range of fracture zone and the bending amplitude of gully slope. The relative position of the working face and the gully controls the connection of the water inrush fracture by limiting the interval distance between the upward fracture of the fracture zone and the downward fracture of the gully. The occurrence of gully indirectly affects the formation of water inrush fracture channel by regulating the deformation degree of slope and changing the size of fracture opening in gully. Based on the above conclusions, combined with fuzzy mathematics method, analytic hierarchy process and disaster index method, the risk assessment model of water inrush in shallow coal seam mining under gully water body is established. The risk area and disaster index of water inrush in 22014 working face are calculated and analyzed, and the local filling scheme of working face is put forward. Field application results demonstrate that roof water inflow in the backfilled areas is significantly reduced compared to the initial unbackfilled areas, realizing safe and efficient mining of the shallow coal seam under the gully water body.

     

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