Influence of Preconditioning and Tunnel Support on Strain Burst Potential.

Strain burst hazard is one of the main challenges that faces deep underground environments. To manage it, it is needed to assess its probability occurrence (or potential). Various methods have been proposed over the years to assess the phenomenon early on. However, due to uncertainties in rock mass properties and the physical processes of the phenomenon, mitigation measures are an additional important line of defense to ensure workplace safety. While work has been carried out to assess the rockburst hazard better and improve support systems, the effect of mitigation measures on strain burst hazard potential is unclear. This paper studies the influence of the implementation of shotcrete and rockbolts support and destress blasting in tunnels on strain burst potential, based on two-dimensional numerical models of circular tunnels. The results highlight that, as expected, the use of mitigation measures allows the strain burst occurrence to decrease. However, the strain burst hazard level does not decrease easily, even when using mitigation measures. In the case of serious overbreak hazards, only a combination of system support and destress blasting seems to have an impact on these events, and not for all the simulated cases. [ABSTRACT FROM AUTHOR]