Damage of Underground Rocks Due to Engineering Activities

加拿大经济严重依赖自然资源，直接和间接地占名义GDP的20%和180万个就业岗位（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。在世界范围内，岩石工程的深度增加是一个趋势。例如，世界上最深的十个矿井中有两个（基德溪和克赖顿）都位于加拿大安大略省。这些地雷有两公里深。******世界范围内岩石工程项目深度增加的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。增加掘进深度对工程结构安全的影响主要表现在两个方面：一是开挖过程扰动了岩体的应力状态，破坏了地下洞口周围的岩石材料；其次，受损岩体在高地应力和附近工程活动扰动的共同作用下，容易发生灾难性破坏。******申请人研究项目的长期目标是以实验为主的方法，全面了解地下岩石在热、水文、机械耦合载荷作用下的损伤及其对地下岩石工程结构安全的影响。在以往研究的基础上，本项目的短期目标是：(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作为应力历史或应力路径函数的定量规律。此外，还将研究应力损伤岩石材料的响应。******为了实现研究目标，确定了三个研究课题：模拟地下开挖采用板状岩体模拟材料；任务2。开挖引起的岩板损伤分布及定量分析任务3。模拟地下条件下应力损伤岩石材料的静、动态试验。当前提案的新颖之处包括首次设计高速、非接触测量的实验室开挖测试，以及使用岩体模拟材料作为物理模型。******地下深处的高地应力条件需要详细而有效的力学分析。数值模拟是岩石力学研究的常用手段，近年来在岩石力学研究中出现了大量的数值模拟研究。然而，开发的数值代码需要对其假设、算法和材料模型进行强有力的验证，以对抗高度控制和充分仪器化的实验室实验。因此，本文拟通过实验模拟地下开挖过程，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.******