Improved Procedures for Analyzing the Deformation and Failure Responses of Brittle Rock in High Stress Environments

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Industry forecasts indicate that there will be a significant increase in production from underground mass mining operations over the next decades as available resources trend deeper. Experiences from these operations have already demonstrated that the rock mass responses encountered at the depths being considered are complex and severe. These have exposed limitations in existing predictive tools. From a support design perspective, the high stress environments and complex stress paths involved are outside the experience-base represented in the empirical design tools being relied upon. Recent successes in my research activities have identified the need for deformation-based support design where brittle failure mechanisms like spalling are involved. However, the numerical tools relied upon to calculate deformation responses are dominated by shear-based models and assumptions of volumetric dilation, whereas the excessive bulking seen in spalling pillars clearly point to an extensional failure mechanism and directional dilation. For this, we have developed a first-of-its-kind 3-D confinement-dependent strength mobilization model and associated 3-D directional dilation model for brittle rock. Complementing this is a pillar-scale 3-D bonded-block modelling technique we've developed capable of explicitly modelling excavation-scale brittle failure and rock mass bulking due to geometric incompatibilities when broken pieces of rock move relative to each other as they are squeezed into the excavation, together with the performance response of different support strategies to these. The research proposed for this Discovery Grant will build on these successes to further advance our understanding of brittle rock mass deformation and failure, while taking important steps to advance and validate the tools we've developed. This will be achieved through research objectives that will see HQP trained in both the state-of-practice and state-of the-art in rock mass characterization, rock mechanics testing, interpretation of mine monitoring data, and advanced numerical modelling. Together, the research program proposed will help to deliver and promote the use of new tools and knowledge more suitable for the challenges that will be encountered as Canadian mines progress to greater depths. Best practice guidelines will be produced that will help contribute to better management of deep mining stresses and adverse rock mass responses through improved support design strategies. Close collaboration with existing industry partners will help to ensure that research deliverables (knowledge, tools, methods, etc.) will be quickly and effectively transferred, facilitating optimization opportunities and improved safety on a reduced time-line between R&D of new techniques and their implementation. HQP will learn skills that are in high demand in the Canadian resource industry and are of strategic importance for Canada's future natural resource development needs.