Characterizing behaviour of healed rockmass structures

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In modern base metal mining featuring particularly deep (>500 m) underground excavations and large open pit slopes, effective geotechnical characterization of the rockmass is critical to the initial excavation and ground support design, and to the accurate prediction of rockmass behaviour throughout project development. Large-scale open pit and block cave mining methods are popular approaches to exploit large orebodies due to the high projected global supply and demand forecasts, increased production rates, and improved worker safety. Mining is a significant industry in New Brunswick and Canada; the Canadian mining industry ranks in the top 5 countries in global production of 13 major minerals and metals. The entire industry contributed $56 billion to Canada's GDP in 2015.The primary objective of this research program is to gain further understanding of the behaviours of healed elements of rockmass structure and their contributions to rockmass behaviour around underground excavations and rock slopes. Healed rockmass structures, termed intrablock structures, occur within fracture-bounded blocks of otherwise-intact rock, which influence rockmass deformability and strength. Intrablock structures are not conventionally considered during geotechnical investigation, characterization and analysis in rock engineering projects. However, in particularly deep mining excavations at high stress, these structures have been observed to control additional or delayed development of ground failures, through what is traditionally considered to be intact rock, or a predictable, naturally-fractured rockmass. These unexpected ground failures require additional ground support on a reactive basis, which increases the safety risk to workers as well as project ground support costs. As excavations continue to go deeper, fractures will have less influence on rockmass behaviour, but intrablock structures have no depth limit and will have increasing effects on stability, safety, and mine economics.This research program will focus on the field examination of intrablock structures and their relationship to ground behaviour, laboratory analysis of mechanical properties, and integration into numerical simulations for geotechnical design applications. Major themes to direct the short-term goals of this research include development of a comprehensive intrablock structure database, improvement of geotechnical data collection and sample selection methodologies, geotechnical laboratory testing of rock with intrablock structure, and the integration of intrablock structure into advanced discontinuum numerical models for rockmass behaviour prediction of deep seated failures in large open pit mine slopes and around deep excavations in block cave mines.1 PhD, 4 MSc and 5 URAs will be trained during this DG research program and will gain significant exposure in industry and academia.