Large-magnitude seismicity at the Westwood mine, Quebec, Canada

摘要

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.