this paper gives an overview of the difficulties associated with the design of hard rock pillars in south african mines. recent examples of large scale pillar collapses in south africa suggest that these were caused by weak partings which traversed the pillars. currently two different methods are used to determine the strength of pillars, namely, empirical equations derived from back analyses o...

This paper gives an overview of the difficulties associated with the design of hard rock pillars in South African mines. Recent examples of large scale pillar collapses in South Africa suggest that these were caused by weak partings which traversed the pillars. Currently two different methods are used to determine the strength of pillars, namely, empirical equations derived from back analyses o...

In some instances, extensive room-and-pillar workings can collapse with little warning and pose a serious risk to underground miners. Traditional strength-based pillar design methods applicable to coal or hard-rock mines use a factor of safety defined as pillar strength divided by pillar stress. Factor of stability, defined as local mine stiffness divided by post-failure pillar stiffness, may o...

Pillars with width-to-height ratios of less than 1.0 are frequently created in underground hard rock mines. The strength of slender pillars can be estimated using empirically developed equations. However, the equations can provide variable results when the width-to-height ratios approach 0.5. This paper investigates some of the issues affecting pillar strength at low width-to-height ratios in h...

1Department of Zoology, University of Otago, P.O. Box 56, Dunedin, New Zealand. *Author for correspondence. R02051 Received 26 November 2002; accepted 9 June 2003; online publication date 19 November 2003 Abstract Body colour is an important distinguishing feature in a New Zealand alpine weta hybrid zone and is strongly correlated with mitochondrial DNA haplotype variation. To assess the broade...

In underground mining, the design of rock pillars is crucial importance as these are structures that allow safe mining by maintaining stability surrounding excavations. Pillar often a complex task, it involves estimating loads at depths and strength mass fabric, which depend on intact shape pillar in terms aspect ratio (width/height). The also depends number, persistence, orientation, discontin...

Historically, the design of the in-stope pillar in underground excavations has been based on empirical formulae and numerical modelling. Although these design methods have been extensively applied in several gold mines in South Africa, rockburst, in-stope pillar burst/failure are continuously reported as the major problem faced by mines. Therefore, this study attempts to compare the performance...