西北矿区隔水层稳定性采动渐序变形机理与开采尺寸效应

The fragile ecological environment and precious water resource in Northwestern coalfield cannot bear the large-scale and high-intensity mining. The key of determining the scientific production capacity of colliery or coalface is to study the effect of mining dimensions on aquiclude stability. The aquiclude instability is caused by the subsequential deformation of main roof and medium constrained strata. The project focuses on the mechanisms of overburden sequential deformation influencing on aquiclude stability and effects of mining dimensions, which contains that: the deformation-permeability coupling regulation is tested to determine the deformation index and the criterion of aquiclude stability in response to underground mining; according to the mechanical theory on multiple bed, a mechanical model on sequential overburden deformations of lower main roof, medium constrained strata and upper aquiclude is constructed to analyze the relations between lower main roof, medium constrained strata and upper aquiclude in combination of 3D modeling results, and then the effects of mining dimensions on aquiclude stability is analyzed and the methods on determining the threshold of mining dimensions are discussed. The expected achievements will improve the connotation on the water protection in underground mining and provide some theoretical base on determining scientific production capacity.

我国西北矿区脆弱生态环境特别是水资源条件难以承载大规模、高强度集中开采，研究基于水资源保护的矿井/工作面科学产能的关键为隔水层稳定性的开采尺寸效应，而隔水层失稳是由基本顶破断渐序诱发中间阻隔层变形破坏导致的。因此，项目围绕隔水层稳定性采动渐序变形机理与开采尺寸效应，分析测试隔水层变形-渗透性耦合规律，确定隔水层采动稳定性的变形指标及其判据；基于复合层板力学理论建立“下位基本顶—中位阻隔层—上位隔水层”采动覆岩整体渐序变形力学模型，融合改造升级的三维采场围岩裂隙-渗流耦合物理模型、覆岩渐序变形-渗流耦合数值模拟，揭示下位基本顶、中位阻隔层移动变形与上位隔水层稳定性变形指标间的关系，研究不同尺寸条件下隔水层稳定性的采动渐序变形规律，探讨基于隔水层采动稳定性的极限开采尺寸确定方法。预期成果可丰富我国西北矿区保水开采内涵，为探索基于水资源承载力的科学产能确定方法提供相应的理论依据。

针对西北煤炭大规模、高强度集中开采中水资源保护问题，选取西北矿区典型弱胶结地层为主要研究对象，基于“中位阻隔层决定上位隔水层变形程度、下位基本顶影响中位阻隔层裂隙扩展”的学术思路，通过分析“开采尺寸、覆岩渐序变形、隔水层采动稳定性”的内涵及三者间的关联，揭示出隔水层采动稳定性的开采尺寸效应。本项目分析了全应力应变条件下隔水泥岩和普通砂岩渗透率变化规律，并得到了隔水泥岩和普通砂岩全应力应变过程中渗透率变化拟合函数，同时将临界压阻比作为衡量隔水层采动稳定性的关键指标，得到了开采扰动后隔水层不发生渗漏破坏的判别方程；分析了不同采高覆岩“下位基本顶—中位阻隔层—上位隔水层”采动渐序变形规律，并建立了基于复合层板结构的覆岩阻隔水层合板力学模型，得到了采后各岩层应力计算方法；基于隔水泥岩和普通砂岩渗透率与应变之间的函数关系，建立了弱胶结地层采动水力耦合数值模拟计算模型，分析了不同开采尺寸条件下“下位基本顶—中位阻隔层—上位隔水层”采动渐序变形规律，以隔水层孔隙压差和渗流速度为衡量指标得到了基于隔水层采动稳定性的极限开采尺寸确定方法。研究成果可丰富我国西北矿区保水开采内涵，为我国西北生态脆弱矿区基于水资源保护的科学产能确定方法的提出奠定了一定基础。