Functional specifications for in-stope support based on seismic and rockburst observations in South African mines

Abstract

Rockbursts pose a significant risk to workers in deep gold and platinum mines in South Africa. In-stope support systems are one of the measures used to mitigate the risk. Over the last two decades several new technologies have been introduced, such as prestressed elongates, roofbolts and nets. However, seismic theory and observations present several characteristics of seismically-induced ground motion that are not taken explicitly into account in the functional specifications for support design, i.e. multi-cyclic shaking, shear motion between hanging and footwall, transient tensile forces, and structural resonances. Investigations of rockburst damage were reviewed to evaluate the significance of these phenomena. Similar phenomena affect surface structures exposed to earthquake-induced shaking, and earthquake engineers have developed a range of solutions to mitigate damage. These solutions are reviewed to evaluate whether the principles of earthquake-resistant design can be adapted to the underground environment. Finally, functional specifications for rockburst-resistant in-stope support are proposed.