库区烧变岩下伏煤层开采覆岩破坏及导水裂隙带预测研究

    Research on overburden failure and prediction of water-conducting fracture zone in underlying coal seam mining under burnt rock in reservoir area

    • 摘要: 张家峁煤矿常家沟水库下伏5−2煤层开采后,准确掌握工作面上覆烧变岩的破坏特征及导水裂隙带发育高度是保障工作面安全高效生产、实施绿色保水开采的前提。以5−2煤层15205工作面覆岩为研究对象,通过模型试验及现场实测对该工作面覆岩移动规律及其导水裂隙带高度进行了研究,以张家峁井田现有导水裂隙带高度实测数据为依据,构建了适用于水体下伏5−2煤层导水裂隙带高度的非线性预测模型,并与模型试验和现场实测结果进行了对比分析。结果表明:现场钻孔探查结果显示该煤层工作面导水裂隙带高度为75.20~75.60 m,裂采比为12.53~12.60;矿区水文地质工程地质勘查规范计算得该煤层工作面导水裂隙带高度为74.12 m,裂采比为12.35,误差为1.7%;相似模型试验得到该煤层工作面导水裂隙带高度为84.5 m,裂采比为14.08,误差为12.0%;综合该矿区现有导水裂隙带的研究成果建立预测模型计算得该工作面导水裂隙带高度为74.48 m,裂采比为12.41,误差为1.2%。预测模型能反映5−2煤层上覆烧变岩导水裂隙带的实际分布规律,具有较好的准确性和工程适用性,为该煤层的水害防治提供了可靠依据。

       

      Abstract: After the extraction of the 5−2 coal seam beneath the Changjiagou Reservoir at the Zhangjiamao Coal Mine, accurately understanding the failure characteristics of overlying burnt rocks and the development height of water-conducting fracture zones on the working face is essential to ensure safe and efficient production and implement environmentally friendly water-preserving mining practices. Taking the overlying rocks of the 15205 working face of the 5−2 coal seam as the research object, a study is conducted on the movement characteristics of the overlying rocks and the height of the water-conducting fracture zones on this working face through model experiments and on-site measurements. Based on the measured data of existing water-conducting fracture zones in the Zhangjiamao Mining Area, a nonlinear prediction model suitable for the height of water-conducting fracture zones below the water body in the 5−2 coal seam is constructed. A comparative analysis is conducted with the results of model experiments and on-site measurements. The research results show that the on-site drilling results indicate that the height of the water-conducting fracture zone on the coal seam working face ranges from 75.20 m to 75.60 m, with a fracture-to-mining ratio of 12.53 to 12.60. According to the mining area hydrogeological engineering geological exploration norms, the calculated height of the water-conducting fracture zone on the coal seam working face is 74.12 m, with a fracture-to-mining ratio of 12.35, resulting in an error of 1.7%. The similar model experiments yield a height of 84.5 m for the water-conducting fracture zone on the coal seam working face, with a fracture-to-mining ratio of 14.08, resulting in an error of 12.0%. Integrating the research results of the existing water-conducting fracture zones in the mining area, a predictive model is established to calculate the height of the water-conducting fracture zone on this working face, resulting in a height of 74.48 m and a fracture-to-mining ratio of 12.41, with an error of 1.2%. The predictive model can reflect the actual distribution law of water-conducting fracture zones in the overlying burnt rocks of the 5−2 coal seam, demonstrating good accuracy and engineering applicability, and providing a reliable basis for water hazard prevention and control in this coal seam.

       

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