采动岩体裂隙时空演化及渗流灾变基础研究

Based on the scientific problems of seepage catastrophe and crack evolution of mining rock mass, the seepage mutation mechanism of water inrush through mining rock mass cracks was mainly studied. Applying the true triaxial rock testing system of coupled stress-seepage, the time-space evolution process of rock sample with large size was traced and pinpointed to study the influence of three dimensional stress and seepage pressure on seepage feature. Combining with numerical simulation and water inrush simulation with similar materials, evolution characteristics of flow pattern catastrophe and instantaneous and delay feature of water inrush were analyzed. Based on mutation theory, the mutation model of floor water inrush was built, obtaining floor water inrush criterion on time scale by field observation. Meantime, the relationship of joint network generation and coupled stress-seepage dynamic system instability of rock mass was established according to multi-field coupling theory, gaining mining response pattern from stress-seepage coupling effect and evolution, revealing the influence mechanism of water inrush due to seepage catastrophe resulted from coupled stress-seepage effect on stablity deterioration of rock mass structure, and then the new cognitive of catastrophic water inrush mechanism was proposed, which had important theoretical significance and application value for guranteeing coal safety production.

本项目紧紧围绕采动岩体裂隙扩展演化及渗流灾变这一科学问题，着力研究采动岩体裂隙渗流突变突水的成灾机理。利用岩石应力-渗流耦合真三轴试验系统，对大尺寸岩样的裂隙时空演化过程进行精确定位和追踪，研究三维应力和渗透水压变化对渗流特性的影响，并结合数值模拟和突水相似材料模拟，分析采场突水形成过程中流态灾变的演化特征及突水的瞬时突发和延迟特性。基于矿井底板突水的突变理论，建立底板突水突变模型，结合现场勘验，获得时间尺度下的矿井底板突变突水判据。在此基础上，基于多场耦合理论，建立断裂节理网络产生与岩体应力-渗流耦合动力系统失稳之间的关系，获得应力-渗流耦合效应及其演化对采矿活动的响应规律，揭示采动岩体应力-渗流耦合效应对岩体结构稳定性劣化而导致渗流灾变突水的影响机理，进而提出采场灾变突水机理研究的新认知，对保障矿井煤炭的安全生产具有重要的理论意义和应用价值。

采动岩体裂隙时空演化规律及突水通道形成过程和渗流突变成灾机理是矿井突水灾害防治的关键性问题之一，研究成果可为矿井工程的设计、计算和安全生产奠定更加可靠合理的基础。项目研究按照研究计划和研究目标，紧紧围绕采动岩体裂隙扩展演化及渗流灾变这一科学问题，通过MTS815.03岩石伺服实验，获得变形引起的裂隙和孔隙变化是引起岩石试件渗透率变化的根本原因，岩石的渗透特性与岩石的岩性和所处环境的围压密切相关。基于矿井底板突水的突变理论，将固有导水通道和完整隔水层突水两种模式的内在机理用尖点突变模型来描述，建立了底板突水平衡曲面的方程、通过坐标变换获得分支曲线方程，得到了平衡曲面与分支曲线。将隐伏构造突水模式的内在机理用蝴蝶突变模型来描述，获得了隐伏构造型突水模式的势函数的标准形式、平衡曲面的标准方程和控制平面内的分支曲线方程。基于Comsol Multiphysics多物理场耦合分析软件，建立了含水层-断层-工作面三个阶段的断层导通前后达西-非达西-自由流动方程，获得应力-水压力作用下断层水突出及流动机理。通过应力渗流耦合真三轴试验，建立了考虑节理粗糙的单一裂隙渗透系数方程。试验表明：三维应力都对裂隙的渗透起抑制作用，其中裂隙法向应力对裂隙渗透的影响非常明显，起主导作用。随着三维应力的增加，岩样的渗透系数逐渐减小，说明应力的增加使裂隙逐渐闭合，摩擦阻力增大。通过对渗透系数的试验数据进行拟合，得到了渗透系数随三维应力和渗透水压变化的公式。研制了新型固流耦合相似材料，通过相似材料模拟试验，直观地展现了含隐伏断层底板在采动应力扰动和高承压水共同作用下底板裂隙形成、隐伏断层扩展、突水通道贯通的全过程，获得了采动底板及隐伏小断层裂隙发育扩展演化规律。结合对现场采动岩体破坏范围实测数据分析，进而提出了采场底板高承压水致灾的相关措施，研究成果对保障矿井煤炭的安全生产具有一定的理论意义和应用价值。