A study of post-peak behaviour of rocks and pillar instability in deep underground mines

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As mining progresses to deep grounds, mining-induced rock failure, seismicity and rockburst problems increase significantly. A good mine design strives to avoid rockburst problems in the first place, and achieving this objective requires a good knowledge of the rock mass behaviour, especially in the post-peak region. For example in mine pillar design, the knowledge of rock's post-peak behaviour is essential in the assessment of pillar burst potential. The objectives of the research are to develop fundamental knowledge on the post-peak behavior of rocks, to study the influence of loading path on the post-peak behavior of rocks, to develop a novel method to investigate the influence of machine stiffness on post-peak behavior of rocks, to develop an innovative method to calculate mine stiffness, and to develop a methodology for assessing anticipated pillar instability in underground mines. It would be extremely difficult, if not possible, to study all these problems experimentally in laboratory. Hence, the approach to be adopted is a combined application of experimental observation and numerical modeling. This approach will take data from past laboratory test programs and validate and calibrate some of the advanced numerical tools to be used in this study. The research findings from this study can deepen our knowledge of post-peak strength of rocks, and contribute to a better understanding of the interaction between the pillar rock and the surround rocks. The outcome of the research will improve our capability to evaluate more accurately whether a pillar will fail violently or not. Most importantly, the results from the proposed research will contribute to the mineral resource sector in Canada for resource recovery in a more productive but less risky manner. In addition, two graduate students (one MASc, one Ph.D) will be trained in the course of the project.