A pressure pulse is being applied to the tunnel boundary with a frequency of 4 Hz over tens of milliseconds. Quiet (i.e., viscous) boundaries have been applied to all but the top of the model, which remains a free surface.
Operations at Westwood mine in Quebec, Canada were temporarily halted in May 2015 after three large-magnitude seismic events occurred over two days. The mechanisms leading to these events, which caused severe damage to several accesses, were not well understood at first. This paper presents the key aspects of FLAC3D back-analysis modelling, which include (1) an anisotropic rock mass strength model with properties derived from field and laboratory strength testing, and (2) a scheme to account implicitly for the deconfinement that accompanies buckling around excavations.