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薄基岩区覆岩采动破坏特征与控水控砂性能评价

Characteristics of overlying rock mining failure and evaluation of water - sand controlling performance in thin bedrock areas

  • 摘要: 针对浅部煤层露头区近松散含水层下开采溃水溃砂问题,以鲁西煤矿3126工作面为工程背景,采用物理模拟、数值模拟与现场实测三者相结合的方法,研究了该工作面覆岩破坏特征及导水裂隙带高度,基于黏土层、风氧化带和保护层建立了控水控砂关键层的评判标准及控水控砂性能评价体系,结合现场实测裂采比预计了不同采高条件下导水裂隙带高度,进而确定了不同基岩厚度条件下的限高开采方案。结果表明,在采高3.5 m条件下,物理模拟和数值模拟导水裂隙带高度分别为43.5、46.5 m,裂采比分别为12.43、13.29,而现场实测导水裂隙带高度为41.51 m,裂采比为11.86;3126工作面上覆黏土层和风氧化带控水控砂性能高,因此,影响安全开采的因素主要为保护层的控水控砂性能,其主要取决于剩余基岩厚度与采高比值。不同基岩厚度条件下的分段限高开采方案,为提高开采上限和防治新生界底部松散含水层水害提供了理论依据。

     

    Abstract: Aiming at the problem of water and sand collapse during mining under the near loose aquifer in the exposed area of shallow coal seams, and taking the 3I126 working face of Luxi Coal Mine as the engineering background, a combination of physical simulation, numerical simulation, and on-site measurement was used to study the characteristics of overlying rock failure and the height of water conducting fracture zone in this working face. Based on the clay layer, wind oxidation zone, and protective layer, the evaluation criteria and the performance evaluation system for the key strata of water-sand controlling have been established. Combined with the ratio of the field measured height of fractured zone to mining height, the height of water conducting fracture zone under different mining height has been predicted, and then the limited height mining plan under different bedrock thickness conditions has been determined. The results show that under the condition of 3.5 m mining height, the height of water conducting fracture zone is 43.5 and 46.5 m, and the ratio of the height of fractured zone to mining height is 12.43 and 13.29 in physical simulation and numerical simulation, while the field height of water conducting fracture zone is 41.51 m and the ratio of the height of fractured zone to mining height is 11.86 in field measurement. The overlying clay layer and wind oxidation zone on the 3I126 working face have high water-sand controlling performance, the main factor affecting safe mining is the water-sand controlling performance of the protective layer, which mainly depends on the ratio of remaining bedrock thickness to mining height. The segmented limited height mining plan under different bedrock thicknesses provides a theoretical basis for increasing the mining limit and preventing water hazard in the loose aquifer at the bottom of the Cenozoic.

     

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