Abstract
Advancements in Rockburst Mitigation at Vale’s Deep Mining Operations in Sudbury – Case Studies
Yao, M., Landry, D., Mamidi, N.
Vale Canada Ltd, Sudbury, ON, Canada
ABSTRACT:
Over the last decade, Vale Canada Limited’s Sudbury Operations have experienced an increase in the occurrence of significant seismic events. Common contributing elements identified through seismic event investigations include: 1) high quality rock mass conditions combined with high-strength, brittle material properties; 2) elevated stress levels associated with increased mining depths (up to 2.5km from the surface); 3) unfavorable mining geometries, such as sill and diminishing rib pillars; 4) higher extraction ratios, reflecting the maturity of mine operations; and 5) interaction with seismically active geological structures (joints, faults, dykes and shear zones etc.). Mitigation strategies focused on those identified contributing elements have been developed within Vale’s North Atlantic Operations, to manage and control the risks associated with seismicity and rockbursting.
This paper presents two unique rockburst events, including: 1) a major fault-slip induced burst in a sill pillar, and 2) a major strainburst due to the change of mining geometries. For each event, comprehensive investigation and analyses have been undertaken to identify the failure mechanisms, the contributing factors, the lessons learned and, most importantly, the development of additional mitigation strategies to minimize and/or prevent future re-occurrence of similar rockburst incidents. The investigation results for all the two unique cases are presented in this paper, and it is hoped that sharing case studies will provide rock mechanics engineers some insight into when rockburst activity might be anticipated and what mitigation strategies can be adopted when similar mining scenarios are encountered at their operations.[SN1]