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Destress blasting is regarded as an active mitigation measure for preventing rockbursts in deep underground works, whose mechanism and effectiveness, however, have still been in debate. A self-developed combined finite-discrete element method software is implemented in this study to first model the rock fracture process induced by a single-hole destress blasting based on a practical blast in a deep gold mine with high in-situ stresses. The effects of accelerometer holes and bedding planes are discussed. Then, a two-round tunnel face excavation in deep underground with high in-situ stresses is modelled, which reproduces the occurrence of the excavation-induced rockbursts. Finally, destress blast-holes are introduced into the same model prior to the two-round tunnel face excavation to investigate the effect of the destress blasting on the excavation-induced rockbursts. It is found that the fractures induced by the destress blasting shift the high abutment pressure induced by the excavation away from the tunnel face and then protect the tunnel wall from fracturing. The numerical modellings reveal that the success of the destress blasting in controlling excavation-induced rockbursts depends on not only the site condition but also the design of the destress blasting such as the arrangement of the blast-holes and the explosive charges. [ABSTRACT FROM AUTHOR]

• Rock blasting was simulated by a unique self-developed GPGPU-parallelized FDEM. • Dynamic interactions of in-situ stresses, blast loading and fracturing were modelled. • Rock fracture and fragmentation process was properly replicated. • Effects of in-situ stress field and lateral pressure coefficient were clarified. • Effects of blasting decay time ratio and decoupling ratio were elucidated. One highly effective approach for tunnelling in rock at deep depth is blasting. The damage and in-situ stress redistribution in the surrounding rock mass induced by the blast loading during this process is, however, unavoidable. In this study, a powerful GPGPU-parallelized combined finite-discrete element method is implemented to study the damage evolution during controlled contour blasting in the bench of a deep-buried tunnel. The proposed method is characterized by the simulation of the blasting-induced pressure variation via the pressure-gas volume history curve and the modelling of the transition from continuum to discontinuum behaviour in the surrounding rock mass. The in-situ stress distribution, the blasting-induced stress wave propagation, and the corresponding rock fracture and fragmentation process are modelled and analysed. The numerical simulation results indicate that the in-situ stresses play a key role in the damage evolution around the tunnel, strongly influencing the stress redistribution pattern and thus the fracture initiation and propagation around the tunnel during blasting. Several different in-situ stress regimes are considered and discussed, revealing the dominating effects of the major principal stress and lateral pressure coefficient on the rock damage behaviour. Moreover, the blasting results obtained from employing the pressure–time history curve with varying decay time ratios and decoupling ratios are also studied. Longer decay time ratios and higher decoupling ratios induce additional rock fracture and fragmentation, indicating that the model can enable the selection of stemming and explosive type for effective breakage with limited damage around a tunnel. [ABSTRACT FROM AUTHOR]