Hazard assessment when mining orebodies under shear loading

This paper presents causes for elevated hazards in orebodies with inclined far-field stresses and shows that numerical and empirical approaches used in the analysis of orebodies under normal far-field stress loading conditions can give misleading conclusions when applied to sheared orebodies. Example procedures for identifying potential hazards in sheared orebodies and planning for such hazards are given using the F-Zone of Campbell Red Lake Mine. The F-Zone of the Campbell Red Lake Mine is not continuous, has offsets and is under shear loading and thus is unique in the study of orebodies under shear loading. The primary objective of this study was to provide guidelines for the safe and economic extraction of remnant sill and boxhole pillars in the F-Zone. The guidelines were to include identification of safe and economic distances of drifts (drift layout) for remote access to the orebody. A Drifts@Risk approach developed for drifting in stressed ground at the Laurentian University Geomechanics Research Centre was utilized to establish setbacks for future developments and the identification of the optimum drift layout.