Browsing by Author "Thibodeau, Denis"

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    Mining Of Orebodies under Shear Loading Part 1 - Case Histories
    (Maney Publishing, 2011) Suorineni, Fidelis T.; Kaiser, P. K.; Mgumbwa, Juma J.; Thibodeau, Denis
    The conditions for rockbursts occurrence are traditionally identified as: high stress, highextraction ratio, strong brittle rocks, folding, faulting and unfavourable excavation geometry.Some rockbursts cannot be explained by any one or a combination of these factors. Salamon(1983) stated that a disconcerting feature of rockbursts is that they defy conventional explanation.Based on detailed review of case histories, this paper identifies oblique loading of orebodies bythe major far field principal stress as a cause of rockbursts. Orebodies subjected to this loadingcondition are termed orebodies in shear. Orebodies in shear are subjected to compressive andshear loads. This paper shows it is risky to generalise that tabular orebodies have their axisperpendicular to the major far field principal stress. This study identifies characteristics oforebodies in shear and the consequences of not taking this loading mechanism into account inthe planning, design and mining of such orebodies.
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    Mining Of Orebodies under Shear Loading Part 2 -Failure Modes and Mechanisms
    (Taylor and Francis, 2014) Suorineni, Fidelis T.; Mgumbwa, Juma J.; Kaiser, P. K.; Thibodeau, Denis
    Part 1 of the paper defined shear loaded orebodies and showed through case histories that bothpillars and excavations are at elevated risks of failure when mining these orebodies. Part 2 of thepaper presents new knowledge on the behaviour of pillars and excavations when mining suchorebodies. Numerical modelling is used to understand the behaviours of these structures in theorebodies. It is established that pillars in shear suffer confinement loss compared to theirequivalents under pure compression. The confinement loss increases with increasing shearloading in pillars with width : height (W : H)§1. For pillars with W : H §1, the Lunder andPakalnis (1997) empirical pillar design chart should be used with caution. For excavations ineccentrically loaded orebodies, passive and active high stress envelopes are created in theexcavation process. The combined effect of the active high stress and tension zones often resultsin excavation surface sloughing.