Grants and Contributions:

Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023)

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.