Rigby, A 2023, 'Dynamic modelling of strainbursting around tunnels', in J Wesseloo (ed.), Ground Support 2023: Proceedings of the 10th International Conference on Ground Support in Mining, Australian Centre for Geomechanics, Perth, pp. 151-164, https://doi.org/10.36487/ACG_repo/2325_10
(https://papers.acg.uwa.edu.au/p/2325_10_Rigby/)
Abstract: Crush-type seismic sources locating to tunnels are abundant at many mines, particularly those where stress is high and the rock is competent. These events are associated with the dynamic stress fracturing of rock around a tunnel and the convergence of the surrounding elastic rock mass into the tunnel’s void. When associated with observable damage to the excavation, such events are termed strainbursts. Given that strainbursts can pose significant risk both in terms of safety and impact on production, understanding the demand they place on the ground support system is a problem of practical interest. 
The demand placed on support by a given strainburst depends on how failure in the rock develops dynamically in space and time. While some information about this failure can be inferred from seismic data, it cannot provide a full description on its own. To gain further insight, we have conducted dynamic threedimensional modelling of strainbursting around a tunnel for various cases of loading conditions and rock mass properties. 
The results of these cases are analysed to quantify aspects of the source dynamics. In particular, we estimate the velocities and durations of failure propagation axially along the tunnel and radially outwards from the tunnel's surface. It is shown that these velocities, particularly in the case of radial propagation, are significantly lower than that expected for confined shear failure. We have also determined moment tensors, which give information about static/permanent deformation at the source. For each of the modelled cases, the moment tensor was of crush-type with a P-axis approximately aligned with maximum in-plane loading of the tunnel.

Keywords: strainbursting, numerical modelling, seismic sources