Damage initiation, fracture evolution to failure in deep excavations in structured rock for mining, tunnelling and deep storage - Getting dilation, degradation and structural displacements right for prediction, field verification & observational desi

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Disposal of high-level nuclear waste is a critical engineering challenge for all countries that generate nuclear power. Safety assessment of deep rock excavations for waste storage is primarily concerned with maximum extent of the excavation damage zone (EDZ) and fluid mobility within this halo. Deep rock tunnelling for roads, rail, water, hydro-power, pipeline routing and resource storage often involves rockmasses that are jointed (naturally fractured) at depth. Damage initiates as the tunnel is advanced and evolves to create tunnel face and wall failure and possible rock-bursting (violent failure). In mining, tunnels are required for short-term ore access and long-term critical infrastructure. While earlier support design was based on calculations of unstable rock load and energy release (rockburst), modern design must consider displacement potential and capacity. In support of these three applications, modern engineering simulation tools can predict damage initiation and overall extent of yield within a uniform, unstructured rockmass in deep and high stress conditions. Accurate representations of the post yield dilation, void generation, bulk volume change and boundary displacement in deep tunnelling remain elusive as reliable outputs from current analysis. The common link between the applications described above is the need to predict and verify through monitoring displacements in the initial stages of construction through to long-term evolution of progressive and dynamic deformations within the rock adjacent to the constructed void. Where discrete structure exists (joints,veins), the accurate prediction and meaningful monitoring of deformations becomes a major challenge, but one that must be solved for effective and safe observational design in these conditions. This research will involve a trifecta of research environments including mechanical testing in the Queen's Geomechanics Lab, advanced discontinuum/continuum modelling, and assessment of past and currently ongoing excavations. 12 HQP will be trained through the proposed research program, building on past contributions in excavation damage research, support analysis, long-term deformation and damage prediction, advanced modelling and key developments in state-of-the-art monitoring. The proposed research for this DG focuses on evolving damage-induced deformation, including time-dependent and dynamic response of EDZ, controlled by stress path,  and geological structure. Practical guidance for displacement-based support design as well as deformation back-analysis and monitoring will be key outcomes. The result will be robust and intelligent observational design for deep construction in structured brittle rock, improving worker safety, support reliability, and monitoring effectiveness. This work will create a step change in reliability of engineering assessments and designs, reducing risk costs and improving project viability for Canadian underground infrastructure worth $Billions.