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.

中文翻译：

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深埋隧道台面等高爆破岩石损伤演化的FDEM模拟

一种在深部岩石中开挖隧道的高效方法是爆破。然而，在此过程中爆炸载荷引起的围岩破坏和原位应力重新分布是不可避免的。在这项研究中，采用强大的 GPGPU 并行组合有限离散元方法来研究深埋隧道台阶受控轮廓爆破过程中的损伤演变。所提出的方法的特点是通过压力-气体体积历史曲线模拟爆破引起的压力变化，并模拟围岩中从连续体到非连续体行为的转变。对原位应力分布、爆破应力波传播以及相应的岩石破裂和破碎过程进行建模和分析。数值模拟结果表明，地应力在隧道周围损伤演化中起关键作用，强烈影响应力重新分布模式，进而影响爆破过程中隧道周围的裂缝萌生和扩展。考虑和讨论了几种不同的地应力状态，揭示了主要主应力和侧压力系数对岩石损伤行为的主要影响。此外，还研究了使用具有不同衰减时间比和解耦比的压力-时间历史曲线获得的爆破结果。更长的衰减时间比和更高的解耦比会导致额外的岩石断裂和破碎，