Volume 35, N. 1, January-April 2012 | PAPER(28 downloads)
Probabilistic and deterministic stability analyses of the progress of a large mine pit excavation in Brazil are presented herein. A simple method of reliability analysis for quantifying the probability of failure of slopes has been considered and its advantages and limitations are briefly discussed. The variance of the factor of safety is computed for several stages of the mine excavation. It is shown that, depending on the slope height, either the friction angle or the effective cohesion may be the most important variable controlling stability. In the case of mine pit excavations ranging from 50 to 400 m in height, pore pressures are of lesser relative importance. Consequently, increasing the capacity of the horizontal drainage system may be of limited efficiency in stabilizing potentially unsafe mine slopes. In addition, variables with no significant effect on the stability, such as the apparent specific gravity of the slope material, may be simply considered as deterministic parameters.