Location Map for the 218-W-4B/C Burial Ground (Low-Level Waste Management Area 4) Showing the Location o f Cross Sections. .. .. . Cross Section A-A' through the 218-W-4B/C Burial Ground. .. .. .. Cross Section B-B' through the 218-W-4BjC Burial Ground. .. .. .. Cross Section C-C' through the 218-W-4B/C Burial Ground. .. .. .. North/South-Oriented Cross Section through the 200 East Area. .. . East/West-Oriented Cross Section through the 200 East Area. .. . .

The Westwood mine is located approximately 40 km east of the town of Rouyn-Noranda and 80 km west of the town of Val-d'Or in Quebec, Canada. Operations at the Westwood mine were halted by three large-magnitude seismic events which occurred over two days in May, 2015. This paper provides an overview of the seismic events and summarises the numerical back-analyses completed using global mine-scale and local drift-scale models, to gain an understanding of the mechanisms that fundamentally contributed to what was considered, by a review panel of experts, to be an unforeseen series of events. A global mine model was required to provide a reasonable estimate of the induced stresses on nearfield pillars and excavations and a detailed small-scale model was necessary to adequately capture the failure mechanisms in drift ribs, which played a role in sublevel pillar performance. The global model did not provide sufficient resolution to capture drift-scale mechanisms. While the local model was insufficient for calibration of the mine system boundary conditions, the combination of global and local models is valuable in defining mine-scale stress conditions and their impact on local, drift-scale failure mechanisms.

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