Underground infrastructures are crucial for resource extraction, energy storage, and space utilisation. The geomaterials that make up these structures, such as rock and concrete, are subjected to multiaxial stress conditions and are frequently exposed to dynamic and extreme loadings caused by both natural disasters and human activities. These stresses are particularly significant during the construction phase, which involves operations such as drilling and blasting excavation, as well as during the operational phase, which may include events like explosions. For instance, while drilling and blasting induce rock breakage within the excavated profile as designed, they inevitably lead to the formation of a damage zone in the surrounding rock mass. Moreover, the cumulative effects of sequential excavations and multiple blasts can cause significantly greater damage, thereby threatening the stability of tunnel structures during the operation phase. This paper highlights the importance of thoroughly analysing these phenomena during both static and dynamic loadings to ensure the stability of underground infrastructures. To address these challenges, a rate-dependent damage constitutive model is proposed for geomaterials to assess the impacts of blasting loads and the cumulative damage resulting from repeated blasts. The model is conceptualised using the strength envelope of loading-unloading curves to represent the progressive accumulation of damage under repeated impacts. Through theoretical derivation, a dynamic cumulative damage model is developed, based on a modified Mohr-Coulomb strain-softening model incorporating rate-dependent parameters, and is validated against dynamic experimental data. The model captures the transition between static strain-softening and dynamic cumulative damage, triggered by a critical strain-rate threshold. The applicability of the model is demonstrated through simulations of tunnel excavation, emphasising the impact of blasting loads and the accumulation of damage zones. To assess its practical feasibility, the developed model is applied to simulate different excavation scenarios for an underground hydropower cavern. Damage in the surrounding rock mainly results from static unloading and/or dynamic disturbances. Blasting construction, in particular, causes significant damage in tunnel intersection zones and the connecting areas of two benches, leading to increased displacement and higher damage levels compared to static excavation. To mitigate excessive damage while maintaining the construction timeframe, it is recommended to consider alternating cycles of dynamic loading and static excavation unloading continuously, which helps understand damage formation in critical zones without significantly delaying project completion.

中文翻译：

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动态累积损伤模型构建及其在多次爆破下水电地下洞室中的应用


地下基础设施对于资源开采、能源储存和空间利用至关重要。构成这些结构的地质材料（例如岩石和混凝土）会受到多轴应力条件的影响，并且经常受到自然灾害和人类活动引起的动态和极端载荷。这些应力在施工阶段尤其重要，涉及钻孔和爆破挖掘等操作，以及操作阶段，其中可能包括爆炸等事件。例如，虽然钻孔和爆破会按照设计在开挖的剖面内引起岩石破碎，但它们不可避免地会导致在周围岩体中形成损伤区。此外，连续开挖和多次爆破的累积效应会造成更大的破坏，从而在运营阶段威胁到隧道结构的稳定性。本文强调了在静态和动态载荷下彻底分析这些现象以确保地下基础设施稳定性的重要性。为了应对这些挑战，提出了一种与速率相关的地质材料损伤本构模型，以评估爆破载荷的影响和重复爆破造成的累积损伤。该模型使用加载-卸载曲线的强度包络线进行概念化，以表示在重复冲击下损伤的逐渐积累。通过理论推导，基于包含速率相关参数的改进 Mohr-Coulomb 应变软化模型，开发了动态累积损伤模型，并针对动态实验数据进行了验证。 该模型捕获了静态应变软化和动态累积损伤之间的过渡，由临界应变率阈值触发。该模型的适用性通过隧道开挖的模拟来证明，强调爆破载荷的影响和损伤区的积累。为了评估其实际可行性，开发的模型被应用于模拟地下水电岩洞的不同挖掘场景。周围岩石的损坏主要由静态卸载和/或动态干扰引起。特别是爆破施工，会对隧道交叉区和两个台阶的连接区域造成重大破坏，与静态开挖相比，导致位移增加和损坏程度更高。为了在保持施工时间框架的同时减轻过度损坏，建议考虑连续交替进行动态加载和静态开挖卸载的循环，这有助于了解关键区域的损坏形成，而不会显着延迟项目完成。