Damage of Underground Rocks Due to Engineering Activities

加拿大经济严重依赖自然资源，直接和间接占名义GDP的20%和180万个工作岗位（加拿大统计局，2014年）。这些工作和活动大多与地下岩石的挖掘有关。岩石工程的深度增加是世界性的趋势。例如，世界上最深的十个矿井中的两个（基德溪和克雷顿）都位于加拿大的安大略。这些矿井有2公里深。 岩石工程项目深度增加的全球趋势导致了重大的安全问题，因此对加拿大经济产生了不利影响。深度增加对工程结构安全的影响有两个方面：第一，开挖过程扰乱了岩体的应力状态，从而破坏了地下洞室周围的岩石材料;第二，受损的岩石材料在高地应力和附近工程活动引起的扰动的共同作用下，因此容易发生灾难性的破坏。 申请人的研究计划的长期目标是充分了解由于耦合热，水文和机械载荷及其后果的地下岩石工程结构的安全性，主要使用实验方法的地下岩石损伤。本研究的短期目标是在前人研究的基础上，（1）揭示应力损伤的一般机制，（2）了解应力损伤岩石的力学响应。将建立描述岩石损伤随应力历史或应力路径变化的定量规律。此外，应力损伤岩石材料的响应将进行调查。 为了实现研究目标，确定了三个研究主题：任务1。模拟地下开挖使用的岩石块模拟材料制成的板;任务2。由于开挖，岩石板中的损伤分布和量化;任务3。模拟地下条件下应力损伤岩石材料的静态和动态试验。目前提案的新颖之处包括首次设计了高速非接触式测量的实验室开挖试验，以及使用岩体模拟材料进行物理模型。 具有高地应力的深层地下条件需要详细有效的力学分析。人们通常采用数值模拟的方法，岩石力学中的数值模拟研究也出现了一股热潮。然而，开发的数值代码需要严格验证他们的假设，算法和材料模型对高度控制和充分仪器化的实验室实验。因此，该建议计划通过实验模拟地下开挖过程，并为数值研究提供基准，这对岩石力学和岩石工程至关重要。

The Canadian economy heavily depends on natural resources, which directly and indirectly accounted for 20% of nominal GDP and 1.8 million jobs (Statistics Canada 2014). Most of these jobs and activities are associated with the excavation of underground rocks. There is a worldwide trend for depth increasing in rock engineering projects. For example, two of the ten deepest mines in the world ( Kidd Creek and Creighton) are both located in Ontario, Canada. These mines are over 2 km deep. The worldwide trend of increasing depth in rock engineering projects leads to grand safety concerns, and therefore adverse implications to Canadian economy. The effects of increasing depth to the safety of engineering structures are two folds: first, the excavation process disturbs the stress state of the rock masses and thus damage the rock materials around the underground openings; second, the damaged rock material is under combined action of high in situ stresses and disturbances induced by nearby engineering activities and is thus prone to catastrophic failures. The long-term goal of the applicant's research program is to fully understand the underground rock damage due to coupled thermal, hydrological, and mechanical loads and its consequences on the safety of underground rock engineering structures using mainly experimental methods. Built on previous studies, the short-term objective of this project is (1) to reveal the generic mechanisms of stress-damage and (2) to understand the mechanical response of stress-damaged rocks. Quantitative laws describing the rock damage as a function of the stress history or the stress path will be established. In addition, the response of stress-damaged rock materials will be investigated. To achieve the research objective, three research topics are identified: Task 1. Simulated underground excavation using a plate made of rock mass analogue material; Task 2. Damage distribution and quantification in the rock plate due to excavation; Task 3. Static and dynamic tests of stress-damaged rock materials under simulated underground conditions. The novelties of the current proposal include the first design of the laboratory excavation test with high speed, non-contact measurements, and the usage of a rock mass analogue material for the physical model. Deep underground conditions with high in situ stress require detailed and valid mechanical analysis. People usually resort to numerical simulations and there has been a surge in numerical simulation study in rock mechanics. However, the numerically codes developed need vigorous validations of their assumptions, algorithms, and material models against highly controlled and adequately instrumented laboratory experiments. This proposal thus plans to experimentally mimic the underground excavation process and provide benchmarks for numerical studies, which is essential for the rock mechanics and rock engineering.