The influence of underground workings on slope instability mechanisms

Numerous examples exist within the literature of slope failures promoted by underground workings, some with catastrophic consequences. This paper investigates the influence of underground workings on the failure mechanisms of both natural and man-made slopes. Conventional analysis of such problems is difficult as limit equilibrium stability analyses do not allow for the vertical and horizontal movements that accompany underground workings and the associated induced weakening of rock/soil mass strength. The results of discontinuum (distinct element) and continuum (finite difference) modeling of slopes influenced by underground mining are discussed. The potential influence of underground mining on slope stability is illustrated with reference to the Frank Slide, a catastrophic slope failure which occurred in Alberta, Canada in 1903.