渗透压-热力耦合作用下岩石变形劣化过程细观试验与机理耗散分析

In view of high geostress, high temperature and high osmotic pressure shown in underground mining engineering, oil and gas engineering and nuclear waste disposal engineering, the mesoscopic damage mechanics problem due to the deformation and degradation process of rocks under the coupled thermo-hydro-mechanical action have become an international hot issue among the research on rock mechanics and engineering nowadays. By use of rock failure process mesomechanical test system, the coupled thermo-hydro-mechanical behaviour rocks is investigated by conducting a series of mesoscopic dynamic experiments (including unaxial, triaxial loading and unloading) on natural and precracked rock specimens. The mesoscopic structure of the rock can be quantitatively described by dynamic tests with the help of digital image processing technology. Using the mesoscopic damage mechanics and energy dissipation theory, the internal mechanism of energy dissipation in the deformation and failure process of rock is revealed. In addition, the damage evolution law showing initiation, nucleation, expansion, coalescence of micro-cracks in complex conditions is quantitatively described, and the micro-macro damage evolution equations under the coupled thermo-hydrological action are established. The strength loss and failure criteria are proposed based on energy dissipation and releasable strain energy. Numerical method is put forward in order to simulate the propagation evolution process of cracks. The research is not only a breakthrough as well as innovation in the field of rock mechanics, but also has an important theoretical significance for underground rock engineering.

针对深埋地下采矿工程、油气工程及高放核废料处置工程具有高地应力、高温、高渗透压之特点，渗流场-应力场-温度场耦合作用下岩石变形劣化全过程的细观损伤力学问题成为当今国际岩石力学与工程研究的热点。本项目利用岩石破坏全过程细观力学实验系统，通过对天然和人工裂纹岩石试件在渗透压-热力耦合作用下进行单轴、三轴加载、卸荷全应力应变过程细观动态试验研究，用数字图像处理技术对动态试验的岩石细观结构进行定量描述，运用细观损伤力学、能量耗散理论、揭示岩石变形破坏过程中能量耗散的内在机制，定量描述在复杂状态下岩石微裂纹萌生、成核、扩展、贯通至破坏损伤演化规律，建立渗透压-热力耦合作用下岩石宏-细观损伤演化方程，给出基于能量耗散的强度丧失准则和基于可释放应变能的整体破坏准则，提出相应的数值计算方法，实现动态模拟裂纹扩展演化过程。此课题的研究解决是岩石力学领域的突破与创新，且对地下岩石工程加固有重要的理论指导意义。

针对深埋地下采矿工程、油气工程及高放核废料处置工程具有高地应力、高温、高渗透压的特点，渗流场-应力场-温度场耦合作用下岩石变形劣化全过程的细观损伤力学问题成为当今国际岩石力学与工程研究的热点。本项目首先利用岩石破坏全过程细观力学实验系统，将全数字电液伺服加载系统、高精度升温系统和SEM结合起来，开展大理岩、砂岩细观力学试验，观察温度-应力耦合作用下大理岩、砂岩的细观力学行为和损伤演化特征，运用细观损伤力学、能量耗散理论揭示岩石变形破坏过程中能量耗散的内在机制，建立岩石宏-细观损伤力学模型；对经历冻融循环的砂岩开展单轴压缩试验、三轴卸荷试验和扫描电镜试验，分析冻融循环对砂岩力学特性的影响和细观演化特征；其次研究内蕴单裂隙、双裂隙透明类岩石材料在单轴压缩条件和双轴压缩条件下的裂纹扩展规律，分析裂纹扩展对类岩石材料力学特性的影响，并考虑渗透压和应力耦合作用下的裂纹扩展规律，分析变形劣化过程中微裂纹萌生、成核、扩展、融合、贯通至破坏的全过程；然后开展温度应力耦合条件下的岩石变形劣化过程的时效特性研究，建立温度应力耦合条件下的非线性蠕变模型；最后开发细观图像处理程序，提高细观扫描图像处理的精度和效率，编制数值计算程序，采用扩展有限单元法，实现动态模拟裂纹扩展演化过程。此课题的研究是岩石力学领域的突破与创新，对复杂环境下地下岩石工程围岩稳定与安全有重要的理论指导意义。该项研究成果发表科技论文25篇，其中SCI论文4篇，EI论文5篇，培养博士1名，硕士 9 名。