Addressing the Consequences of Dynamic Rock Failure in Underground Excavations

Abstract

Rockbursts are violent events that result in the ejection of volumes of rock from the walls of underground excavations. They can be extremely hazardous and have been responsible for many accidents in underground excavations. They also are responsible for significant direct and indirect costs in mining and civil engineering projects. The occurrence of rockbursting can be reduced by optimising the design with regard to excavation layout, excavation geometry and size, excavation sequence, and by the application of destressing/preconditioning measures. Thereafter, containment of damage relies on rock support. Conventional design of rock support for the containment of rockburst damage is not possible since neither the demand that is generated, nor the capacity of support systems, are known, and thus there is a state of design indeterminacy. The approach recommended in this paper is a risk-consequence one: evaluation of the risk (the product of the probability of occurrence of a rockburst and its consequence, in financial terms), and use of this quantified risk as a decision making tool regarding the justification for significant dynamically capable rock support. A typically suitable rock support system for rockbursting conditions is suggested in the paper.