Study on the “collusion” mechanism of blast-Induced cracks under initial compressive stress

Initial compressive stress has a significant impact on the “collusion” of blast-induced cracks. This study uses a dynamic caustics experimental system to conduct blasting experiments on parallel collinear and non-collinear defects, aiming to explore the effects of initial compressive stress and defect spacing on the propagation and interaction of blast-induced cracks, and to reveal the “collusion” mechanism of blast-induced cracks between parallel double defects under initial compressive stress. The research results show that the promoting effect of initial compressive stress on crack propagation and the suppressing effect of “collusion” of blast-induced cracks on crack propagation exhibit different strengths at different defect spacings. However, initial compressive stress can increase the stress intensity factor (SIFs) and propagation velocity of the main crack during its initiation and propagation process, suppressing the mutual repulsion of the “collusion” crack tips and making the “collusion” between blast-induced cracks more tightly bound. As the defect spacing increases, the promoting effect of initial compressive stress gradually dominates, becoming more significant than the suppressing effect of crack “collusion.” In addition, numerical simulations were used to study the evolution of the full-field stress under the action of blasting stress waves and double defects, and to analyze the stress-time curves at the defect tips.