Studies on directional breaking controlled theory of slotted cartridge blasting for rock

Abstract

This paper adopts the red sandstone as blasting medium, studies the mechanism of rock breaking caused by slotted cartridge blasting, analyzes the crack distribution characteristics, sets up “rock-explosion crack” of three-dimensional reconstruction model, and accurately describes the explosion crack location and the shape of space distribution. The results show that there are only two cracks generated along the slotted direction of slotted cartridge blasting, and the crack position was symmetrical. Combining the calculation method of three-dimensional fracture fractal dimension with CT scanning, we quantitatively describe the evolution process of explosion fractures. The damage degree of rock after blasting with slotted cartridge was 56.5% lower than that of common charge. From the CT scan results and the numerical analysis, it can be concluded that slotted pipe causes plastic deformation, making the slotted pipe fit with blast-hole wall, and stress concentration occurs at the slotted pipe incision. The stress concentration intensity is greater than that in other areas, leading to the crack formation. Slotted cartridge initial crack formation location is at the joint of “slotted pipe incision and blast-hole wall.” It shows that the slotted cartridge can reduce the degree of damage caused by explosive, effectively protecting the damage caused by explosion to shaft wall.