Adapting to rapid change in demand for ground support systems at Jokisivu mine

Authors: Di Giovinazzo, M; Ridaskoski, T Download Paper

DOI https://doi.org/10.36487/ACG_repo/2625_43

Cite As:
Di Giovinazzo, M & Ridaskoski, T 2026, 'Adapting to rapid change in demand for ground support systems at Jokisivu mine', in D Cumming-Potvin & J Wesseloo (eds), Ground Support 2026: Proceedings of the 11th International Conference on Ground Support in Mining, Australian Centre for Geomechanics, Perth, pp. 1-10, https://doi.org/10.36487/ACG_repo/2625_43



Abstract:
This paper presents an assessment of adapting ground control practices for deeper stope mining at the Jokisivu narrow-vein longitudinal benching gold mine in Finland. Existing ground support systems in oredrives – primarily 2.4 m hydroformed expansion friction rockbolts and plain shotcrete – performed well for the majority of the mine’s 8-year operational life. However, this system proved unsuitable for responding to the rapid onset of stress-induced damage at depths greater than 300 m. Structured observational and analytical investigations were conducted to understand failure modes and their timing. Observed damage ranged from intact rock failure forming a fractured excavation surface leading to spalling, through to occasional larger falls of ground, likely associated with seismic shakedown. Unreinforced shotcrete applied after expansion friction rockbolts debonded and failed together with spalled slabs, while rockbolt and plate performance remained adequate. Damage was dominated by brittle, stress-induced spalling of intact rock in drive backs and shoulders, driven by high horizontal stresses induced during panel retreat toward a central access and upward toward sill pillars. Spalling depths ranged from 0.5 to 1 m in both stiff massive diorite and slightly weaker veined diorite and pegmatite. Available mine equipment and ground support products were reconfigured to implement immediate changes to ground control systems, improving both ground support reliability and personnel safety. The initial modification – installing weld mesh over existing plain shotcrete, with three-square mesh overlaps secured using the original 2.4 m expansion friction rockbolts – demonstrated significantly improved risk mitigation. For new development, ground support standards were modified to include either fibre-reinforced shotcrete or weld mesh reinforced plain shotcrete secured with the same hydroformed expansion rockbolts. Controlled installation practices for development advance were implemented, oredrive development timing was adjusted, sill pillar sizing and stope extraction sequencing were optimised. The lowest extracted stoping panel, at depths of 585–645 m, was successfully completed in 2024 to planned extraction tonnage and rates. Despite increased rock noise events, no significant falls of ground were recorded.

Keywords: ground support, demand change, ground conditions, spalling damage, rehabilitation, development timing

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