Rock damage induced by underground excavation would cause irreversible degradation in the hydro-mechanical performance of the engineering rock mass depending on the excavation method, in-situ stress, and change of ambient conditions. As exploitation of resources continues being operated at hostile depths of the Earth's lithosphere, adaptive excavation design thus becomes imperative for ensuring sustainable mining development in the increasingly challenging environment. In this study, a new thermal-mechanical framework is developed to characterize the successive blast loading, transient unloading, and air-cooling sequence for dynamic excavation in prestressed geothermal deposits. To capture the complex rock behavior across vastly different timescales, a new diagnostic tool is proposed for identifying the exact source, nature, and range of excavation damage based on the stress projection technique. By scrutinizing the rock response throughout the excavation process via loading path evolution, novel insights are obtained in this study into the underlying mechanism and relative contribution of each sub-loading process in damage generation under different geopressure, geothermal, and excavation conditions. Our calculations demonstrate quantitatively that the release of in-situ stress and air-cooling of the working environment constitute the predominant causal mechanisms of rock damage for major deep excavation projects. Furthermore, our analysis has shown explicitly that the perturbation to the redistributed stress field by tunnel ventilation could stimulate rock creeping and thus give rise to stability concern for excavations buried in highly stressed deposits of intense geothermal anomalies. The findings of our study could refine the understanding of the complex excavation response and thus contribute to improved adaptive design for excavation work in hostile geological environments.

地下开挖引起的岩石损伤会导致工程岩体水力学性能不可逆的退化，这取决于开挖方法，原位压力和环境条件的变化。随着资源开采继续在地球岩石圈的恶劣深度进行，因此适应性挖掘设计对于确保在日益严峻的环境中的可持续采矿开发变得必不可少。在这项研究中，开发了一种新的热机械框架来表征预应力地热矿床中动态开挖的连续爆炸加载、瞬态卸载和空气冷却序列。为了捕捉不同时间尺度上的复杂岩石行为，提出了一种新的诊断工具，用于基于应力投影技术确定开挖损伤的确切来源、性质和范围。通过加载路径演变来仔细检查整个开挖过程中的岩石响应，地压、地热和开挖条件。我们的计算定量地表明，地应力的释放和工作环境的空气冷却构成了大型深基坑开挖项目岩石损坏的主要因果机制。此外，我们的分析明确表明，隧道通风对重新分布的应力场的扰动可能会刺激岩石蠕变，从而引起埋藏在强烈地热异常的高应力沉积物中的开挖的稳定性问题。我们的研究结果可以加深对复杂挖掘响应的理解，从而有助于改进恶劣地质环境中挖掘工作的适应性设计。