深部开采底板隔水关键层受局部高承压水作用破坏理论分析

Theoretical analysis on failure of water-resisting key strata in the floor by local high confined water in deep mining

大量实测地质资料与防治水实践证实,深部煤层开采底板含水层存在大量的局部高承压水区域,在强开采扰动下极易诱发底板突水灾害。基于"下三带"、"关键层"理论,将局部高承压水与底板隔水关键层简化为圆筒力学模型,分析研究隔水关键层在局部高承压水作用下的屈服破坏机制,得到了隔水关键层发生屈服的4个临界水压值公式;对各临界水压值进行区间划分,分析不同区间隔水关键层的屈服状态,确定了局部高承压水致使隔水关键层屈服破坏两个阶段的水压判据平衡方程,得出了奥陶系顶部岩层作为隔水关键层剩余隔水能力的计算表达式,并反演得到了开采深度上限、下限公式。结合九龙矿深部开采实际,对所建力学模型进行了验证与应用,进而提出了防止局部高承压水致灾的相关措施,对实现深部煤层安全带压开采具有重要的理论指导意义。

In deep mining, there are a large number of local high confined water areas in floor aquifers which can easily induce floor water inrush disasters under strong mining disturbances have been confirmed by measured geological data and water control practices. Based on the theory of ＂lower three zone＂ and ＂the key strata＂, the key aquiclude in the floor and the local high confined water area were simplified into a cylinder mechanical model, and the yield failure mechanism of the water-resisting key strata under the local high confined water was analysed. Four critical water pressure formulas for yielding in the water-resisting key strata were obtained. By dividing the critical water pressure values into sections and analysing the yielding state of the water-resisting key strata in different sections, the water pressure criterion balance equations for two stages of yielding and breaking of the water-resisting key strata caused by local high confined water were determined. The calculation expression of the remaining water-resisting capacity of the Ordovician top rock layer as water-resisting key strata was obtained. In addition, the formulas for the upper and lower limits of the mining depth were obtained by the inverse derivation. By combining with the deep mining practice of Jiulong mine, the mechanical model was validated and applied. Moreover, the relevant measures were proposed to prevent the local high confined water disaster, which has significant theoretical evidence for realising safe mining of deep coal seam.