承压含水层上采煤突水危险性评估研究

Risk Assessment for Water Inrush from Confined Aquifers Located Under Coal Seams

为了评价岩层阻水性能、确定导升带高度,准确评估不同地质和采掘条件下承压含水层突水危险性,实施了井下钻孔水压致裂综合测量,并采用数值模拟方法评估了带压开采突水危险性.实际观测表明,泥岩、粉砂岩、中砂岩、灰岩阻水性能由大到小,导升高度则由小变大;模拟结果显示,当隔水层厚度较大且没有垂向导水构造时,正常地层不会发生奥灰突水;当存在陷落柱时,随着采面推进向陷落柱接近,采矿扰动导致柱体内应力集中及集中范围不断加大,柱体内岩层裂隙活化不断加强,当采动应力集中带与柱体内应力集中带之间煤岩柱不足以抵抗地下水压力时,即发生突水.

Numerical simulations and in-situ surveys of hydraulic fracture have been used to study the water resistance of a rock mass, the possibility for water inrush and the intrusion height under different geological and mining conditions. The surveys show that the water resistance ranges from large to small in the order： mud-rock〉 fine sandstone〉 middle sandstone limestone. The intrusion heights, however, are in the reverse order： mud-rock 〈 fine sand- stone 〈 middle sandstone 〈 limestone. The results of numerical simulations show that the possibility of water inrush is very small for thick aquifuges having no permeable structures. When there are collapse columns in aquifuges, the range of stress concentration become larger and hydraulic activity becomes stronger because of mining disturbances. Water inrush will happen once the coal pillar between stress concentration zoon and collapse columns can not bear the pressure of ground water.