Study on the influence of arched pre-splitting crack on cracks propagation under explosion load

Pre-splitting blasting is extensively utilized in engineering tasks such as tunneling and underground chamber excavation. This study employs Digital Image Correlation (DIC) techniques and Dynamic Caustics Systems to examine the influence of pre-splitting crack, induced by pre-splitting blasting, on the dynamic fracture properties of blasting cracks into the remaining rock mass. The research findings reveal the critical role of pre-splitting crack in increasing damage to the blasted rock mass, impeding the propagation of blasting cracks towards the remaining rock mass, and promoting the initiation and propagation of primary cracks in remaining rock mass, particularly enhancing the cracks at the arch crown and the bottom of the arch abutment. The presence of pre-splitting crack significantly amplifies the strain field around the primary cracks, at the crack tips of these fractures, and near the pre-splitting crack, prolonging the duration of strain intensification. Moreover, pre-splitting crack increases the stress intensity factor at the tips of primary cracks, enabling more efficient energy accumulation before crack initiation. Consequently, the enhanced stress intensity factor at the tips of wing cracks following initiation fosters more rapid energy accumulation during crack propagation, thereby increasing the peak propagation velocity of the wing cracks. The outcomes of this study provide substantial theoretical and experimental support for the safe and efficient excavation of tunnels and galleries.