Deep hard rock mining and rock mechanics challenges

Abstract

Mining at depth is associated with high stress magnitudes and often serious ground control problems. Two different extreme conditions: (a) hard rock and seismic problems, and (b) altered weak ore or weak ore contact zones in a hard host rock mass resulting in large deformations and squeezing conditions, are typical for deep mining in Sweden. A research programme focused on rock support design for deep mining conditions has been conducted at Lulea University of Technology, Division of Mining and Geotechnical Engineering, since 2009. The objective of the research is to improve the understanding of the (i) rock mass response and the rock support system performance, and (ii) the interaction between the rock mass and the rock support system when mining at increasing depth. The programme comprises field monitoring in three mines, looking at large-scale dynamic loading of rock support systems, numerical analyses of different phenomena, failure mechanisms, and details in the rock mass–rock support system interaction. The paper gives examples of activities and programme results. The programme has so far resulted in new knowledge and new questions. In order to improve the understanding of the rock mass–rock support interaction, details are important. Since the programme will run for a number of years, only a few sub-projects are finished and therefore the main conclusions are still not drawn.