Study on the Interaction Between Blasting Stress Waves with Different Incidence Angles and Crack

To better study rock blasting in engineering and the initiation and propagation behavior of the pre-existing crack under blasting stress waves, large-scale rock models containing a thorough centric crack were numerically blasted, using the LS-DYNA and HYPERMESH software for solving, modeling and meshing as well as adding keywords, respectively. The rock material chosen for the present study was granite, and the Holmquist-Johnson-Cook (HJC) model was applied to carry out numerical simulations. To study the influence of incident angle of blasting stress wave, there were four groups of modes in all designed with different borehole positions, labeled as M-1, M-2, M-3 and M-4. Based on the theoretical wavefront reconstruction, the reflection and diffraction of blasting-induced waves at a finite crack and highly complex interaction with crack were explained in detail. Furthermore, the maximum circumferential stress criterion was used to analyze the crack initiation and propagation. The results are in accordance with the experiment results, which show that the incident angles of blasting stress waves have a significant effect on the propagation characteristics of waves at the pre-existing crack and the model failure modes. As the incident angle increases, the initiating time of crack tip B decreases, but the deflecting angle increases, and damage near the pre-existing crack is more serious. In addition, reflected and diffracted waves cause stress concentration at the crack tip, which plays a dominant role in crack initiation and propagation. While the pre-existing crack hinders stress wave propagation and reduces its amplitude and inhibits the formation and development of cracks around the borehole, thereby resulting in that the model damage is mainly concentrated at the crack ends and around the borehole, no obvious damage occurs in other areas.