Rockburst means stress induced violent ejection of rockmass in tunneling and mining. Rockmass comes off under high energy release. To determine this energy, different approaches exist, depending on different countries and regions. Rockburst phenomena mostly occur in deep tunnels and mines but also in regions, where high stress concentrations appear. A major engineering challenge for mines experiencing significant seismicity is the performance of the support systems. The development of an adequate retaining system, such as dynamic rock bolts together with high-tensile steel wire mesh and their behavior during rockburst had been tested and quantified. The special large scale test facility was constructed for that purpose. It allowed the estimation of portions of energy transmitted by rock bolts and wire mesh.

1 Introduction

As more and more near surface deposits are mined out, deeper mines are required in order to continue the exploitation of resources. This inevitably leads to the occurrence of more rock bursting, deformation problems and safety issues. Rock burst means stress induced loosening of parts of the rock mass under enormous energy release. It seems to be similar to damage from natural seismic phenomena. Rock burst events occur mostly in deep tunnels and mines but also in regions with high horizontal stresses.

There are different methods to mitigate rock burst risks thus reducing exposure of personnel. Changes include mine design, layout and extraction sequence (Potvin 2012). In addition the ground support needs to be chosen and designed in such a way that it can cope with the conditions. In deep mines the ground support is complex and cost is high. Static ground support is not satisfactory for such a demanding environment. The ground support consists of the rock reinforcement (e.g. bolt), a surface support (e.g. mesh) and the connection between the two (e.g. plate). For dynamic loads it is essential that these components fit and work together as a system (Cala & Roth 2007). The observations of Heal (2007) show that most of the damage done from rock bursting led to the failure of the surface support or the rupture of the reinforcement.

In order to investigate the dynamic behavior of reinforcement elements and surface support, extensive testing was carried out at various test sites. Some tests were done in South Africa, Canada and Australia. Hadjigeorgiou (2011) put the results of the various tests together and tried to make them comparable. However the boundary conditions of the test sites were different making comparison difficult. There are two active test sites at the moment, one is in Canada at CANMET and the other in Australia at WASM (Player et al. 2004). The WASM test site is the best instrumented facility and is based on the momentum transfer concept. It can test reinforcement, surface support and to a certain extent combinations of the two.

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