深部开采底板煤岩组合体卸荷-渗流破裂演化及灾变机制

With mine mining depth increasing, the mining floor undergo high stress concentration peak under the typical high ground stress and high karst water pressure occurrence environment of the deep rock mass and large-scale and high strength mining of deep coal, which will form the strong unloading effect. Especially, under the action of confined water pressure, high mining stress unloading and drive the floor coal and rock stratum fractured. Then the floor coal-rock combined body form the nonlinearly process of progressive fractured evolution to instability disaster-induced under the non-equilibrium condition, which will induces floor confined aquifer water inrush disasters and cause groundwater resources loss. The geotechnical consulting & testing systems for multi-field coupling, X-ray industrial CT, field monitoring and simulation analysis will be applied to research the project. The linkage effects and partitions characteristics of floor failure under the disturbance of main roof instability in deep coal mining will be analyzed. The research will obtain the fractured mechanical behavior of deep floor coal-rock combined body under unloading and seepage coupling. The failure mechanical model of deep floor coal-rock combined body considering the unloading-seepage and interface effect will be developed. And the progressive unloading-seepage fractured evolution of floor coal and rock stratum in deep coal mining will be revealed from the perspective of macro and mesoscopic mechanics. Based on the interaction of the strong unloading of deep mining stress and the seepage of high confined water pressure, the response characteristics of layered floor water inrush disaster-induced will be researched. And it will provide the grouting reinforcement technologies of floor unloading-seepage partitions for preventing and controlling the confined aquifer water inrush in deep coal mining. Then the project research will provide an important scientific basis for floor water inrush disaster prevention and water protection mining for safety and high efficiency in deep coal mines.

随矿井开采深度增加，深部岩体典型的高地应力、高岩溶水压赋存环境及煤炭大规模高强度开采导致经历高应力集中峰值的采动底板形成强烈的卸荷效应，尤其在高承压水压力作用下，高采动应力卸荷并驱动底板煤岩层破裂，形成了非平衡条件下底板煤岩组合体由渐进破裂演化至失稳灾变的非线性过程，进而诱发底板突水灾害并造成地下水流失。本项目拟通过GCTS多场耦合试验系统、工业CT、现场监测及模拟分析等综合研究方法，分析深部开采底板破坏与基本顶失稳的联动效应及分区特征，研究深部底板煤岩组合体卸荷-渗流破裂的力学行为，建立考虑卸荷-渗流及界面效应的深部底板煤岩组合体破坏模型，从宏细观角度揭示深部开采底板煤岩层的卸荷-渗流破裂演化机理，研究基于深部采动应力强卸荷和高承压水压力渗流相互作用的层状底板突水灾变响应特征，提出深部底板卸荷-渗流分区注浆加固防控技术，为深部矿井底板突水灾害防控和安全高效保水采煤提供科学依据。

随矿井开采深度增加，深部岩体高地应力、高水压赋存环境及煤炭高强度开采导致经历高应力集中的采动底板形成强烈的卸荷效应；尤其在煤层及其顶底板整体力学平衡和高承压水压力作用下，高采动应力卸荷驱动岩体破裂至失稳灾变，从而导致底板突水灾害愈发频繁。.项目从应力增量角度揭示了深部开采顶底板断裂失稳的联动机理及底板端部效应区、卸荷断裂区及触矸效应区的分区特征，明确了底板岩体卸荷断裂的触矸效应；采用GCTS多场耦合试验和CT扫描重构，明晰了深部开采底板煤岩组合体的卸荷断裂特征及渗透演化规律；建立了考虑卸荷-渗流及裂隙结构的深部岩体破坏模型，揭示了深部开采底板煤岩组合体的卸荷-渗流破裂演化机理及灾变响应特征，系统实施构建了基于应力卸荷调控及注浆加固协同的深部开采底板岩体分区分级防控关键技术。.研究表明：（1）基本顶失稳后，底板压力拱后拱脚变换为触矸区，压力拱转换；采深越大，拱脚端部效应区及触矸区压应力增量越高，拱内侧卸荷应力同步增高且增量更大。（2）深部岩体应力卸荷与渗流产生了平行于卸荷方向的拉应力，当该拉应力大于等于岩体围压及裂隙结构抗拉强度之和时，岩体拉破裂且其渗透率非线性突增，突变点恰为岩体拉裂的卸荷量临界值。（3）随初始围压增加，岩体拉裂的围压卸荷终点临界值及剪裂的轴压卸荷起点临界值均线性增加，而两者的围压卸荷量临界值均非线性降低，并服从由浅部低围压卸荷剪裂向深部高围压卸荷拉裂转变规律。（4）在端部效应区随应力增加，渗透系数K先减小，次生裂隙断裂时K增加，当应力大于煤岩体极限强度时，K减小；而在卸荷断裂区，卸荷起点越高，卸荷渗透系数越大，当卸荷至一定值时卸荷渗透系数突变增加。（5）采深及承压水压力越大，岩体渗透率突变点的卸荷量越小；深部开采底板较小的卸荷量可造成隔水层岩体渗透率突变，并诱发底板突水。项目研究成果为深部矿井底板突水灾害科学防控和安全高效保水采煤提供了关键理论和技术支撑。