Abstract Rock fracture process is associated with the degradation and mobilization of the mechanical and strength properties of rock. A number of true triaxial cyclic loading and unloading tests were carried out on three types of hard rocks (i.e., granite, marble and sandstone) to investigate the evolution of the rock properties as a function of accumulated damage. In addition to stress and strain measurements, acoustic emission (AE) signals were monitored and used to associate different stages of crack development with different stages of the mechanical and strength parameter evolution. Young's modulus and five strain increment ratios were calculated from the measured increments of stresses and strains in each cycle. It was found that hard rocks exhibited profound deformation anisotropy and directional dilation. A general trend of decreasing volumetric strain reversal stress and peak stress with increasing plastic strains was observed for all the tested specimens. The evolution of the strength properties of rock under true triaxial compression was investigated using a linear 3D hard rock failure criterion and was found to be generally consistent with the cohesion weakening and frictional strengthening concept. The influence of the intermediate principal stress on the evolution of the rock properties was also discussed.

中文翻译：

---

真三轴循环加载和卸载试验中硬岩力学和强度参数的演变

摘要 岩石断裂过程与岩石力学和强度特性的退化和移动有关。对三种类型的硬岩（即花岗岩、大理岩和砂岩）进行了多次真三轴循环加载和卸载试验，以研究岩石性质随累积损伤的演变。除了应力和应变测量外，还监测声发射 (AE) 信号并将其用于将裂纹发展的不同阶段与机械和强度参数演变的不同阶段联系起来。杨氏模量和五个应变增量比是根据每个循环中测量的应力和应变增量计算的。发现硬岩表现出深刻的变形各向异性和定向膨胀。对于所有测试样品，观察到体积应变反转应力和峰值应力随着塑性应变的增加而降低的总体趋势。使用线性 3D 硬岩破坏准则研究了真三轴压缩下岩石强度特性的演变，发现其与内聚力减弱和摩擦强化概念大体一致。还讨论了中间主应力对岩石性质演化的影响。使用线性 3D 硬岩破坏准则研究了真三轴压缩下岩石强度特性的演变，发现其与内聚力减弱和摩擦强化概念大体一致。还讨论了中间主应力对岩石性质演化的影响。使用线性 3D 硬岩破坏准则研究了真三轴压缩下岩石强度特性的演变，发现其与内聚力减弱和摩擦强化概念大体一致。还讨论了中间主应力对岩石性质演化的影响。