陕北浅埋煤层砂土基型矿区保水开采方法研究

Research on Water-Preserved-Mining in Shallow Seam Covered with Rock Soil and Sand in Northern Shaanxi

在浅埋煤层砂土基型矿区实现保水开采,关键在于煤层开采后含水层和导水裂隙带之间有达到厚度要求的隔水保护层.采用开采损害学中的地表移动变形和采动岩体内部移动变形预计的方法,考虑覆岩中隔水黏土层的膨胀性计算浅埋煤层砂土基型矿区开采后隔水土层中裂隙的破坏深度,同时借鉴相似模拟实验确定导水裂隙带的发育高度,最后计算采高不同时2种裂隙之间的隔水保护层厚度,如果隔水保护层厚度满足规定要求就可以实现保水开采,从而确定砂土基型矿区保水开采的合理开采方法.以榆树湾煤矿20102上工作面开采为例,计算结果表明:5m分层开采可以实现保水开采,放顶煤一次采全高不能实现保水开采.现场开采实践和相似模拟实验验证了该方法的正确性.

The key to achieve water-preserved-mining in the mine area of shallow seam covered with rock soil and sand, is that there should be an impermeable protective layer between the aquifer and water flowing fractured zone after coal mining, with its thickness meeting the qualification. In this paper, adopting the estimation methods of ground movement deformation and movement deformation within rock mass under mining, the damage depth of fractures in the soil impermeable layer is calculated in the shallow seam covered with rock soil and sand, by considering the dilatability of the clay impermeable layer, and the development height of water flowing fractured zone is determined by similarity simulation experiment. Finally, the thick- nesses of impermeable protective layer in the condition of different mining heights are calculated respectively. Therefore, the water-preserved-mining can be achieved if the thickness of impermeable protective layer meets the specified requirement, and the reasonable mining method of water-preserved-mining will be determined in the mining area covered with rock soil and sand. Taking 20102 upper face in Yushuwan coal mine for example, the calculation results show that the water-preserved-mining can be achieved when adopting 5m slicing mining, but can＇t be realized when adopting top-coal caving mining or mining overall height in one times. The correctness of this method has been vetified by mining practice and similarity simulation.