Rojas Perez, C, Wei, W, Gilvesy, A, Borysenko, F-J & Mitri, HS 2024, 'Rockburst assessment and control: a case study of a deep sill pillar recovery', 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. 659-672, https://doi.org/10.36487/ACG_repo/2465_40
(https://papers.acg.uwa.edu.au/p/2465_40_Rojas_Perez/)
Abstract: Rockburst control in deep mining is a challenging problem, especially in high extraction ratio zones. The increased likelihood of rockburst occurrence can be a cause of safety concerns for the mine operators. The parameters associated with rockbursts are generally related to geological features, rock properties, seismic activities and the mining rate. Mining aspects such as mining sequence, mining direction, stope geometry, backfill selection and the mining method all contribute to the occurrence of rockburst. This study demonstrates a stepwise methodology for the assessment and safe recovery of a sill pillar at Agnico Eagle Mines Ltd’s Macassa mine. The pillar is situated 1,700 m (5,600 ft) below surface. It is 110 m (360 ft) long and 15.5 m (50 ft) in height, with a varying thickness averaging 3 m (10 ft). The sill pillar is planned for extraction with longhole stoping in retreat. Past mining activities employed the cut-and-fill method; the levels above and below the sill pillar are tight-filled with paste fill. To assess the stress condition in the pillar, a 3D mine-wide numerical model was created with FLAC3D finite difference code. The numerical model employs the Macassa geomechanical database and in situ stress regime. Pillarburst conditions are assessed using the deviatoric stress ratio to estimate potential brittle shear failure, and the burst potential index based on energy considerations to examine strainburst potential. Model calibration relies on microseismic monitoring activities in the sill pillar over the past year. Rockburst mitigation and control methods with dynamic supports in the sill drives are discussed.

Keywords: rockburst, sill pillar, numerical modelling, rockburst control, pillar recovery, deep mining