ABSTRACT
A generally well accepted methodology for rockburst support design is to consider the energy absorption capacity of the support system and compare that to the energy released during a rockburst. The reality is that both the demand and capacity can only be estimated, and are not precise calculations. Mining support systems typically consist of various types of rock bolts (tendons), coupled with various types of surface support such as mesh or shotcrete. Invariably there is a sharp stiffness contrast between the internal rock reinforcement and the surface support. The component capacities are not strictly additive: for example softer wire mesh may take several hundred millimeters of deformation to reach peak capacity while many tendons reach their peak at a few 10’s of millimeters. Other complications include: pre-loading of the ground support using up some of its capacity prior to the rockburst event; shearing of the tendons where most of the design capacity numbers come from pure axial loading tests; the difficulty of transferring high dynamic loads to tendons with small cross sectional area (loading regime of several square meters transferred to tendons typically in the order a few hundred mm2); complexities during support installation such as irregular rock surfaces, and installation quality.
Despite these limitations many advances have been made in the last few decades, with several examples of mining support systems successfully containing substantial rockbursts. A review of some Canadian Hard Rock mining experience is given dating back to the late 1990s where the development of a rockburst support system began at the now closed Brunswick lead/zinc mine. More recent experience from other Canadian Mines is also discussed. Examples of rockburst support demand and estimated capacity are given, as well as thoughts on possible future improvements.
