Abstract The time-dependence of rock strength is an issue that cannot be ignored in the rock engineering field. This paper summarizes previous study results on the degradation of the uniaxial compressive strength of rock (including component cohesion and internal friction angle), tensile strength and Young's modulus over time. Based on previous studies, the degeneracy formulas of intact rock cohesion and internal friction angle are derived. Taking circular tunnel excavation under hydrostatic pressure as an example, the surrounding rock response is studied under different degradation degrees of rock strength and stiffness, including the radius of the excavation damage zone, damage degree of surrounding rock, lining support pressure and tunnel boundary displacement. The results show that with the increasing degree of degradation of the surrounding rock compressive strength, the above four parameters increase in the form of an exponential function and that weakening of the tensile strength had little effect on the surrounding rock response. In addition, as the degradation degree of rock stiffness increases, the radius of the excavation damage zone remains unchanged, whereas the other three parameters values are reduced. An actual engineering case simulation using the combined finite-discrete element method shows that results consistent with field observations can be obtained if the rock strength degradation law proposed in this paper is adopted.

中文翻译：

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地下基坑周围随时间变化的裂缝发展过程

摘要 岩石强度的时间依赖性是岩石工程领域不容忽视的问题。本文总结了以往关于岩石单轴抗压强度（包括组分内聚力和内摩擦角）、抗拉强度和杨氏模量随时间退化的研究结果。在前人研究的基础上，推导出完整岩石黏聚力和内摩擦角的简并公式。以静水压力作用下圆形隧道开挖为例，研究了不同岩石强度和刚度退化程度下的围岩响应，包括开挖损伤区半径、围岩损伤程度、衬砌支护压力和隧道边界位移。结果表明，随着围岩抗压强度退化程度的增加，上述四个参数均以指数函数的形式增加，抗拉强度的减弱对围岩响应的影响很小。此外，随着岩石刚度退化程度的增加，开挖损伤区的半径保持不变，而其他三个参数值减小。结合有限离散元法的实际工程案例模拟表明，如果采用本文提出的岩石强度退化规律，可以获得与现场观测相符的结果。以上四个参数均以指数函数的形式增加，抗拉强度的减弱对围岩响应影响不大。此外，随着岩石刚度退化程度的增加，开挖损伤区的半径保持不变，而其他三个参数值减小。结合有限离散元法的实际工程案例模拟表明，如果采用本文提出的岩石强度退化规律，可以获得与现场观测相符的结果。上述四个参数均以指数函数的形式增加，抗拉强度的减弱对围岩响应影响不大。此外，随着岩石刚度退化程度的增加，开挖损伤区的半径保持不变，而其他三个参数值减小。结合有限离散元法的实际工程案例模拟表明，如果采用本文提出的岩石强度退化规律，可以获得与现场观测相符的结果。