煤矿采空区碎裂岩体空隙动态演化及储水机理

Utilizing the voids of broken rock in coal mine goaf to store mine water (underground reservoir) has become one of key technologies for the protection and utilization of water resource in ecologically vulnerable coal-mining areas in western region of China. In the technical system, the temporal and spatial evolution law of broken rock voids directly influence the reliability of the reservoir dam and the storage capacity of the reservoirs. In this task, we will take underground reservoir in ecologically vulnerable coal-mining areas of western region as object to explore the distribution law of caving zone’s preexisting fissures in goaf and its development mechanical mechanism under the influence of three-dimensional stress and seepage pressure. Moreover, fractal geometry model of caving strata with different layers will be built to study the caving strata lumpiness in goaf and its distribution law. The influences of lithology, matching degree of particle size and combination mode on the dynamic evolution of water-storage voids of broken rock will also be investigated under the impact of underground pressure, water pressure and mine-induced stress, respectively. Based on the research results mentioned above, the theoretical calculation model for fracture zone of broken rock in roof can be obtained to derive the volume of fracturing zone and spatial-temporal evolution law of storage coefficient of broken rock, which has important scientific and engineering significance for the protection and utilization of coal mining water resources in coal-rich and water-poor mining areas in the west.

利用煤矿采空区碎裂岩体空隙储存矿井水技术（地下水库），已成为我国西部生态脆弱矿区煤炭开采水资源保护与利用的关键技术之一。其中，采空区碎裂岩体空隙的时空演化规律直接影响地下水库坝体的可靠性和水库储水能力。本课题拟选取西部生态脆弱区典型煤矿地下水库为研究对象，探讨采空区冒落岩体原生裂隙分布规律及在三向应力与渗流水压力作用下裂隙扩展力学机理；建立不同层位顶板岩层冒落块度分形几何模型，研究采空区顶板岩层冒落块度及分布规律；探讨在覆岩压力、水压、采动应力等作用下，岩性、粒径匹配等对采空区碎裂岩体储水空隙的动态演化规律的影响；基于以上研究结果，建立顶板岩层断裂空间的理论计算模型，计算采空区碎裂岩体空隙体积，得出采空区碎裂岩体储水系数的时-空演变规律。这对西部富煤缺水矿区煤炭开采水资源保护与利用具有重要的科学与工程意义。

煤炭生产基地地质环境的特殊性决定了在煤炭开发过程中，必须优先保护和科学利用有限的水资源，才能维系和改善脆弱的矿区生态环境。煤矿地下水库技术为我国西部生态脆弱矿区水资源的保护与利用提供了有效途径，而采空区碎裂岩体空隙的时空演化规律则直接影响地下水库的储水能力及运行可靠性。本课题以西部生态脆弱矿区典型煤矿地下水库为研究对象，开发了三维固液耦合相似模拟实验平台、储水结构坝体及储水系数测试装置以及煤水共采专用实验平台（包括煤系沉积岩无损浸水装置、煤岩多功能循环加压浸水装置等），开展了三维固液耦合相似模拟实验、UDEC/PFC/FLAC等数值计算模拟、真三轴压缩/渗流实验、矸石压实实验以及煤矿地下水库储水结构坝体与连接处稳定性分析实验。研究了特殊工程地质条件及煤炭开采条件下地表塌陷与覆岩垮落特征，揭示了采动空间覆岩破断及顶板冒落机理；分析了三向应力与渗流水压力作用下岩石力学损伤及裂隙演化特征，掌握了岩石裂纹演化与扩展机理；提出了采空区碎裂岩体储水系数计算方法，揭示了其在覆岩压力、水压等作用下的时空演化规律，获得了储水结构坝体稳定性影响因素及强度分布特征。研究成果先后在乌兰木伦煤矿、大柳塔煤矿、察哈素煤矿等推广应用，有效保证了地下水库前期区域选址、库容预测以及后期建设运行的安全性与可靠性，为西部生态脆弱矿区煤炭开采水资源保护与利用提供了理论及技术支持。