裂隙水压-应力耦合岩石三维裂纹时空演化特征及扩展机制

Fractured rock mass instability disasters occur frequently with the increasing depth and complication of underground engineering in China. Based on the methods of theoretical analysis, laboratory testing and numerical simulation, the project selects crack propagation as study angle to reveal the temporal-spatial evolution characteristics and propagation mechanisms of three-dimensional cracks under fracture hydraulic pressure - stress coupling. The research results will be conducive to inquiry the instability disaster characteristics and mechanics of fractures rock mass under fluid-solid coupling. First of all, temporal and spatial features of three-dimensional cracks under fracture hydraulic pressure - stress coupling will be obtained through laboratory experiments. The crack fracture information based on different characteristics of AE parameters will be identified. The correlations of stress - displacement - fracture hydraulic pressure will be investigated. Secondly, the quantitative relation between stress drop at crack initiation and energy index will be analyzed. The initiation stress, energy, fracture initiation angle, and other parameters, under fracture hydraulic pressure - stress coupling will be determined using the concept of complex stress intensity factor. The model and criterion of three-dimensional crack propagation under the fracture hydraulic pressure will be developed. Thirdly, based on the above research, a three-dimensional fracture hydraulic flow module will be established to develop and improve a numerical modeling software for simulating the fluid-solid coupling three-dimensional crack propagation. The crack propagation characteristics will be explored under the influence of fracture hydraulic pressure, loading rate, etc. The outcomes from this project will provide the necessary theoretical and technical supports for the prevention and control of fractured rock mass instability disasters under the fluid-solid coupling.

随着我国地下工程的深部化、复杂化，流固耦合裂隙岩体失稳灾害频发，项目从裂纹扩展角度出发，拟采用理论分析、室内试验、数值模拟相结合的研究方法，揭示裂隙水压-应力耦合岩石三维裂纹时空演化特征及扩展机制，探究流固耦合裂隙岩体失稳灾害特征及机理。首先，进行裂隙水压-应力耦合岩石三维裂纹扩展试验，揭示裂隙水压作用下岩石三维裂纹时空演化规律，辨识基于声发射参数的不同性质裂纹扩展特征信息，明确三维裂纹扩展演化过程中应力-位移-裂隙水压的联动响应机制；其次，基于试验数据，分析裂纹起裂应力跌落值与能量释放率的定量关系，揭示裂隙水压-应力耦合条件下起裂应力、能量、角度等，建立裂隙水压作用下三维裂纹扩展模型及判据；最后，以上述研究为依据，建立三维裂隙水流模块，拓展流固耦合三维裂纹扩展模拟分析方法，探索裂纹扩展特征与裂隙水压、加载速率等因素的相关性，为流固耦合裂隙岩体工程失稳灾害防控提供科学依据。

我国基础工程建设强度高、规模大、地质条件复杂，流固耦合裂隙岩体失稳灾害频发，严重制约工程建设及人员安全。流固耦合裂隙岩体失稳灾害本质是裂隙水压-应力耦合作用下裂隙岩体原始损伤扩展演化进而导致宏观失稳所致，并具有很强的随机性、突发性及隐蔽性。本项目在前期研究基础上，将其概化为裂隙水压-应力耦合岩石三维裂纹问题，结合计算机层析扫描、声发射、偏光显微镜等监测检测手段，进行了裂隙水压-应力耦合岩石三维裂纹扩展演化机制研究，分析了岩石三维裂纹空间演化及细观断裂特征，明确了声发射特征参数-应力-应变联动规律及不同裂纹起裂声发射特征，建立了裂隙水压-应力耦合复合型裂纹应力强度因子，表征了裂隙水压、应力、裂纹几何尺寸之间的相互关系，揭示了岩石三维裂纹演化过程中裂隙水压-应力-应变的协同响应特征。以此为基础开展了循环载荷及组合体裂纹演化特征的相关研究，拓展裂纹扩展数值模拟方法及破碎岩体支护措施。该项目为流固耦合裂隙岩体失稳机制研究提供了依据与参考，对地下工程耦合裂隙岩石失稳灾害防控具有重要意义。