Mining of orebodies under shear loading Part 1 – case histories

Abstract The conditions for rockbursts occurrence are traditionally identified as: high stress, high extraction 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 by the major far field principal stress as a cause of rockbursts. Orebodies subjected to this loading condition are termed orebodies in shear. Orebodies in shear are subjected to compressive and shear loads. This paper shows it is risky to generalise that tabular orebodies have their axis perpendicular to the major far field principal stress. This study identifies characteristics of orebodies in shear and the consequences of not taking this loading mechanism into account in the planning, design and mining of such orebodies.

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