Characterisation of burst-prone grounds at Vale's Creighton Mine

Rockbursting is one of the important challenges faced in deep and high stress mines. Ground support systems designed for supporting static loads are often not able to manage the imposed dynamic loads. Consequently, in anticipation of dynamic-loading conditions, stiff support systems are typically enhanced using reinforcement or surface support elements that are perceived to improve the yielding capacity. In order to develop cost-effective ground support strategies, it is important to quantify the conditions that lead to an increased likelihood of rockburst. This paper provides an objective and practical guideline for the identification of burst-prone ground conditions based on the anticipated magnitude events and the associated probability of rockburst, the proximity of large-scale geological structures, and mining-induced stress conditions. The guideline was developed using passive monitoring of ground support performance under dynamic-loading conditions at Creighton Mine, operated by Vale in Sudbury, Ontario, Canada. A comprehensive database was constructed of 123 seismic events and the resulting 184 damage locations. The reported rockbursts occurred between January 2000 and September 2013. The majority of pertinent information was obtained through on-site field assessments, seismic monitoring records, and numerical stress analyses. The proposed guideline is validated for Creighton Mine and the employed methodology is transferable to other deep underground mines.