关闭煤矿采空区积水量预测及其演化过程分析

Analysis of the prediction and evolution process of waterfilling in closed coal mine goaf

  • 摘要: 煤矿关闭之后地下水水位回升,但采空区内的积水演化过程鲜有研究。以徐州三河尖关闭煤矿为例,基于闭坑报告及钻孔数据资料,结合煤层底板标高三维(3D)曲线图确定采空区的积水途径,基于回采空间法分煤层和分水平预测矿井积水量,并依据水力学等相关理论,确定煤矿关闭后各水平的涌水量取值,探究关闭煤矿采空区积水的演化过程。研究表明:根据煤层底板形态3D图预测矿井水首先流向矿井南北两翼的深部采空区及巷道,随后流经矿区东西两翼边缘区域的中部采空区,最后汇集到龙固背斜与张庄断层所在的浅部采空区。三河尖关闭煤矿共计积水9.88×106 m3,其中基于回采空间法计算得到关闭煤矿各煤层积水体积共计9.35×106 m3(采空区和废弃巷道系统积水体积分别为7.86×106、1.49×106 m3),其他储水空间积水体积为0.53×106 m3。随着积水水位的升高,涌水量逐渐降低,在标高为−350~−400 m的水平,涌水量最低,约为134.81 m3/h。煤矿关闭后采空区水位随时间回升的过程表明:积水初期,矿井深部采空区容积小、涌水量大、积水速度快;积水中期,采空区容积增大、涌水量降低且随着巷道数量的增加,积水高度上升速度减慢;积水后期,浅部采空区容积变小,积水高度随时间的增加迅速上升。由此预测煤矿关闭2546 d后地下水将回升至标高为−350 m的水平。

     

    Abstract: After coal mine closure, the groundwater level recovers, while the water accumulation process in goaf areas has rarely been studied. Taking Xuzhou Sanhejian closed coal mine as an example. Based on mine closure reports and borehole data, combined with 3D contour maps of coal seam floor elevations, the water accumulation pathways in goaf areas were identified. The mine water accumulation volume was predicted by mining-induced space method through separate calculations for different coal seams and levels. Water inflow rates at various levels after mine closure were determined using hydraulic theory and related principles, revealing the evolutionary process of water accumulation in abandoned mine goaf. Research shows: According to 3D coal seam floor morphology, mine water first flows to deep goaf areas and roadways in the north and south wings, then passes through central goaf areas in the east and west wing edge zones, and finally converges to shallow goaf areas near Longgu anticline and Zhangzhuang fault. The total accumulated water volume in Sanhejian closed mine is 9.88×106 m3, including 9.35×106 m3 calculated by mining-induced space method (7.86×106 m3 in goaf areas and 1.49×106 m3 in abandoned roadway systems), with 0.53×106 m3 from other water storage spaces. As water level rises, water inflow rate gradually decreases, reaching the minimum value of approximately 134.81 m3/h at −350− −400 m elevation. The groundwater recovery process reveals three phases: initial stage features small deep goaf capacity, high inflow rate and rapid accumulation; mid-stage shows increased goaf capacity, reduced inflow rate, and slowed rising speed with more roadways; final stage exhibits reduced shallow goaf capacity and accelerated water level rise. It is predicted that groundwater will recover to −350 m elevation after 2546 days of mine closure.

     

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