32 / 2021-06-29 14:51:56

Numerical modelling of destress blasting - A state-of-the-art review

Destress blasting; Blasting process; Rock fracturing; Numerical method

As a proactive mine safety measure against the occurrence of rockburst, destress blasting has been applied to numerous mining conditions to precondition highly stressed rock mass to mitigate the risk of rockburst occurrence in deep mines as well as in deep underground constructions (e.g., Drover et al., 2018, Mitri, 2018, Konicek et al., 2013 Konicek et al., 2011, Mitri & Saharan, 2005). However, the application of destress blasting mostly depends on engineering experience, while its mechanism and efficiency have not been well understood (Konicek et al., 2011, Mitri & Saharan, 2005). Rapid advances in computer technology have made numerical simulation an economic and effective method to study the rock blasting effect. Enormous research efforts have been made to numerically investigate the blasting fracture mechanism, optimize blasting design, and assess the efficiency of destress blasting. This review focuses on the state-of-the-art progress in numerical modelling associated with destress blasting over the last two decades. Some commonly used modelling approaches for destressing blasting are compared and reviewed. Currently, two different ways of modelling based on static and dynamic modes are typically used to study the effect of the blasting; see Fig. 1. In the static method, destress blasting is simulated by modifying the stiffness and strength properties of the rock mass to obtain the post-blast stress state in the destressed zone (Tang & Mitri, 2001). The dynamic modelling technique focuses on the dynamic fracture process of coals and rock masses, during which the predetermination of the damage induced by blasting is not necessary (Jung et al., 2011, Xie et al., 2017, Mei et al., 2021). Moreover, the extent of damage zones around the blast hole can be precisely estimated in the dynamic modelling method by considering time-varying blast pressure and strain rate dependency on the strength of rock mass but at the cost of increased computation and complexity. Besides, different destress blasting modelling methods, generally classified into continuum-based, discrete-based, and coupled methods are compared and reviewed. The fracture mechanism of blasting in the rock mass is revealed, and the destressing efficiency of the existing destress blasting design is assessed and compared with classical results. The factors that may affect the efficiency of destress blasting are summarized in Fig. 1. These will be described in more detail. Finally, the difficulties and challenges associated with the numerical modelling of destress blasting are highlighted briefly.