Numerical modelling of the high rock stress challenges at Rana mine, Norway

Authors: Trinh, NQ; Larsen, TE; Molund, S; Nøst, B; Kuhn, A Download Paper

DOI https://doi.org/10.36487/ACG_rep/1952_09_Trinh

Cite As:
Trinh, NQ, Larsen, TE, Molund, S, Nøst, B & Kuhn, A 2019, 'Numerical modelling of the high rock stress challenges at Rana mine, Norway', in W Joughin (ed.), Deep Mining 2019: Proceedings of the Ninth International Conference on Deep and High Stress Mining, The Southern African Institute of Mining and Metallurgy, Johannesburg, pp. 109-122, https://doi.org/10.36487/ACG_rep/1952_09_Trinh



Abstract:
Rana Gruber AS is an iron mining company in the north of Norway, and operates the Kvannevann mine 30 km east of Mo i Rana. The Kvannevann mine is located in a foliated gneiss host rock, with an ore body about 70 m wide and more than 300 m deep. During the history of the mine, it has been in operation for many years using an open-pit mining method, which was later it converted to sublevel-stoping. After thorough planning and preparation, the sub-level cave mining method was put in operation in 2012. Experience from past mining activities and in the preparation of infrastructure for the new mining method indicates that the mine is located in a hard, brittle rock mass with high horizontal stresses. Stress measurements have been made from time to time. The measurement results indicate a major principal stress of approximately 20 MPa perpendicular to the strike of the ore, and a minor principal stress of approximately 10 MPa parallel to the strike of the ore, which is 10–15 times higher than the theoretical vertical stress caused by gravity at the measured location. This paper presents some challenges related to high stress during development and operation of the mine. The paper also presents a comprehensive rock mechanics program, applying a combination of stress measurements, numerical modelling, and monitoring, to deal with the situation.

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