Numerical simulation and application of phased cut blasting in hard rock Roadway in metal mine

In response to the challenges of high rock strength in deep underground metal mines, difficulty in slotting, and low efficiency in excavation, based on the tunneling project at Xingshan Underground Iron Mine of Shougang Corporation, and utilizing precise per-hole blasting with digital electronic detonators, we propose a phased blasting scheme for slotting areas of straight-eye barrel-shaped grooves, combining segmentation within and between holes, as well as delays within each hole. In combination with numerical simulations and field tests, it presents a trench domain gradient detonation configuration with differential detonation in the hole area, between holes and within holes on the basis of the original conventional scheme, builds a three-dimensional(3D) model of the trench domain μsing LS-DYNA numerical simulation software, sets up the original conventional scheme and three gradient schemes for modelling, and provides a comparative analysis of the evolution of the effective peak stress in the dredged-trench zone for the original conventional blasting solution and the staged solution. The results of the numerical simulations show that the μse of short-delay inter-hole blasting can change the fluctuation pattern of the peak effective stress, and compared to the original conventional scheme, the peak effective stress state of the rock in the dredged-trench zone along the direction of the shell hole is increased by 40% to 57%, while the peak effective stress state of the rock in the radiμs of 0-30 cm at the bottom of the shell hole is increased by 84% to 92%. In addition to the numerical simulation results, field experiments were carried out to verify the results. It is clear that the combination of short-delay differential detonation between holes can improve debris crowding in mine excavation, and short-delay differential detonation within holes can improve throwing capacity, improve debris throwing after blasting in the upper part of the shell hole, and avoid affecting the blasting of subsequent shell holes. Incorporating the two in hard rock blasting can significantly improve the blasting effect and increase the hollowing progress by 28%. And better results can be obtained in rock point-excavation by μsing short delay between holes and long delay within hole settings. The results of this paper could provide a reference for similar mine production.