水岩作用下断续裂隙岩石强度劣化及三维裂纹扩展机理研究

Tunnels and reservoir slopes of hydroelectric and traffic engineering often suffer geological disasters induced by underground water during the construction process. Strength deterioration under water-rock interaction and crack propagation of rock caused by excavation significantly influence the stability of rock engineering. Therefore, the strength deterioration and three-dimensional (3D) crack propagation mechanisms of rock under water-rock interaction should be investigated systematically. The background of this program is excavation of tunnels and rock slops in water-rich environment. Based on the experiments of water-rock interaction, rock unloading and analysis of rock microscopic structure, the strength deterioration mechanism of non-persistent flawed rock are reveled, and damage constitutive model for rock under water-rock condition is proposed. Then, the unloading fracture process and 3D crack characteristic of non-persistent flawed rock under water-rock interaction are experimentally studied by using spatial acoustic emission and 3D CT reconstruction techniques. Last, 3D cracking process of non-persistent flawed rock is reproduced and the mesoscopic mechanism of 3D crack propagation is revealed based on the particle flow code that reflects the water-rock deterioration effect. Strength deterioration law, unloading fracture behaviour and 3D crack propagation meso-mechanism of rock under water-rock interaction are expected to obtain, which enhance the theoretical knowledge of excavation construction and stability of rock engineering.

水利水电和交通隧道(洞)、边坡工程开挖建设过程经常遭遇地下水诱发的地质灾害。水岩相互作用下岩石(体)强度劣化，开挖卸荷诱导裂隙发育，严重影响工程围岩稳定。因此，有必要对水岩作用下岩石强度劣化机制和水岩作用下岩石三维裂纹扩展机理等科学问题展开系统研究。本项目以富水环境下隧道、边坡开挖工程为背景，拟通过水岩相互作用试验、岩石卸荷试验和岩石显微图像分析，揭示水岩作用下断续裂隙岩石强度劣化机制，提出水岩作用下岩石损伤本构模型；通过空间声发射定位、CT扫描及三维重构技术，探究水岩作用下岩石卸荷破裂过程，明确岩石卸荷裂纹三维特征；通过编制反映水岩作用劣化效应的颗粒流数值程序，再现水岩作用下岩石三维裂纹扩展过程，揭示岩石三维裂纹扩展细观机理。有望取得水岩作用下岩石强度劣化规律、水岩作用下岩石卸荷破裂机制和水岩作用下岩石三维裂纹扩展细观机理等创新性研究成果，为岩石工程开挖建设与稳定运营提供理论基础。

水利水电和交通隧道(洞)、边坡工程开挖建设过程经常遭遇地下水诱发的地质灾害。水岩相互作用下岩石(体)强度劣化，开挖卸荷诱导裂隙发育，严重影响工程围岩稳定。因此，有必要对水岩作用下岩石强度劣化机制及三维裂纹扩展机理等科学问题展开系统研究。本项目开展了水岩相互作用下岩石三轴压缩试验，获得了饱水岩石强度及变形参数演化规律，分析了水岩作用下岩石变形过程超声波以及声发射特征，探究了损伤程度对岩石渗透率的影响规律。采用声发射及变形场监测、CT扫描等测试手段，开展了预制裂隙岩石加载及卸载试验，获得了裂隙岩石力学参数及破裂模式，分析了岩石破裂全过程声发射-应变场-应力多物理场特征，建立了岩石裂纹演化、声发射与应变场之间的内在联系，揭示了裂隙几何参数和应力条件对岩石裂纹演化的影响规律。采用三维颗粒流程序PFC3D构建了岩石试样数值模型，进行了预制裂隙岩石单轴及三轴压缩，获得了岩石三维裂纹萌生、扩展和贯通全过程，再现了饱水岩石强度特性及破裂特征，分析了岩石变形过程应力场和位移场，揭示了岩石裂纹演化细观机理。研究结论可为岩石工程开挖建设与稳定运营提供理论基础。