Performance of inclined pillars with a major discontinuity

Abstract

Discontinuities are an inherent part of the rock mass and majorly affect the stability of the excavation skin and pillars. The dip of the discontinuities and their properties also have a significant effect on the strength of the pillars. Empirical approaches are commonly used to determine the pillar strength but can overestimate the strength and don’t consider the inclination of the pillars and the strength reduction caused by discontinuities. Numerical modeling is a powerful tool and if calibrated can be used to evaluate the strength of the pillars with discontinuities having a range of properties. The effect of a discontinuity on inclined pillars was conducted which has been seldom considered in evaluating the pillar strength. Three-dimensional vertical pillars were simulated, and the pillar strength was calibrated to accepted theoretical results and then the discontinuities were introduced in different pillar inclinations with distinct width to height ratios to gain an insight into the effective pillar strength reduction. Based upon the results, it was found that the discontinuities have a significant effect with the increase in the inclination of the pillars even at a higher width to height ratios. Keywords: Numerical modelling, Pillar, Discontinuities, Inclination, Width to height ratios