Lessons learnt from a pillarburst at a development heading in one of Vale’s deep mines: a case study

Authors: Yao, M; Hossack, A; Groccia, C Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2465_10

Cite As:
Yao, M, Hossack, A & Groccia, C 2024, 'Lessons learnt from a pillarburst at a development heading in one of Vale’s deep mines: a case study', in P Andrieux & D Cumming-Potvin (eds), Deep Mining 2024: Proceedings of the 10th International Conference on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth, pp. 239-254, https://doi.org/10.36487/ACG_repo/2465_10



Abstract:
Over the last decade, Vale’s Sudbury Operations have experienced an increase in the occurrence of significant seismic events. Common contributing elements identified through seismic event investigations include: high quality rock mass conditions combined with high strength and brittle material properties elevated stress levels associated with increased mining depths (up to 2.5 km below surface) unfavourable mining geometries, such as sill and diminishing rib pillars higher extraction ratios, reflecting the maturity of mining operations interaction with seismically active geological structures (joints, faults, dykes and shear zones, etc.). Mitigation strategies focused on these contributing factors have been developed within Vale’s Mining Operations, to manage and control the risks associated with seismicity and rockbursting. This paper presents a unique rockburst event that occurred in a development breakthrough pillar in the 5220 Ramp at Garson Mine that resulted in injuries to two employees. This event triggered a comprehensive investigation to identify the failure mechanism, contributing factors and lessons learned; forming the basis for additional mitigation strategies, focused on minimising and/or preventing future re-occurrence of similar rockbursts. The investigation results are presented in this paper, and the more recent 5300 Level 1210 Level access breakthrough is presented as an example to demonstrate the successful implementation of a new design methodology and process. It is hoped that by sharing this case study with the industry, ground control professionals can be made aware of when rockbursts may occur, and what mitigation strategies can be adopted when a similar mining scenario is encountered at their operations.

Keywords: pillarburst, deep mines, breakthrough, development headings, seismicity and rockburst

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