Effects of burden on rock crushing characteristics under lateral detonation of cylindrical charges

To investigate the effects of burden on rock crushing characteristics under lateral detonation of cylindrical charges, we analyzed the stress state at the free surface using the wave theory. Afterward, to simulate the cylindrical charge detonation, the physical experiment of lateral rock fragmentation was conducted using direct copper wire electro-explosion. The evolution process of surface crack network of the specimen was observed using ultra-high-speed camera technology. The impact of cylindrical charge detonation on rock properties was studied by combining the morphology, dimensions, and distribution characteristics of the blasting crater with different burdens. The results demonstrated that the burden is a crucial factor for controlling the fracture mode, morphology of failure zone, and fragment size during rock blasting. As the burden increased, the crack propagation velocity and density gradually decreased, while the range of crack network expanded, and the preferential propagation direction of cracks changed from transverse to circumferential. Furthermore, the experimental results indicated an increasing trend in the short axis of the fracture zone as the burden increased. Through analyzing the stress state at the free surface, the maximum tensile strain criterion was applied to justify this phenomenon. Finally, the relationship between fragment size and energy consumption was established. Our research findings provide a reference for optimizing the design of rock engineering blasting.