Andersson, J, Svartsjaern, M, Shekhar, G, Boskovic, M, Swedberg, E & Töyrä, J 2024, 'Evaluation of barrier pillar for seismic hazard reduction at the Kiirunavaara mine', in Daniel Johansson & Håkan Schunnesson (eds), MassMin 2024: Proceedings of the International Conference & Exhibition on Mass Mining, Luleå University of Technology, Luleå, pp. 992-1006.
(https://papers.acg.uwa.edu.au/p/2435_G-11/)
Abstract: In May 2020, the largest mining-induced seismic event ever recorded in Sweden occurred in the LKAB Kiirunavaara sublevel caving mine. The incident caused significant damage along several hundred meters of drifts. Following the incident, production was paused in the affected area (called Block 22; B22) and two main actions plans for resuming production were developed: (i) leave a temporary residual sill pillar that could be recovered, or left behind, as part of resumed sublevel caving, or (ii) leave a permanent barrier pillar constituting the entirety of B22, effectively dividing the Kiirunavaara Mine into a northern and southern portion. While both actions plans were evaluated from a rock mechanics perspective, the design and evaluation of the latter is the focus of this article. The design and evaluation process for the barrier pillar option was split in two parts. Part 1 considered the quasi-static stability of the barrier pillar and potential seismic indicators as well as the placement of the pillar with respect to minimizing ore losses in B22. A crucial step in this part was to define criteria for stability and thresholds for seismic potential. Part 2 of the evaluation assessed the influence of the barrier pillar on mine infrastructure. In the end, LKAB choose to move forward with the alternative with a barrier pillar of approximately 600 m width extending down to the 1365 m level to be left in the area. The decision was primarily based on the rock mechanics analysis and modeling results presented here.