Weakly confined slotted cartridge blasting in jointed rock mass

Abstract

Directional fracture blasting can improve the smooth blasting effect of layered jointed rock masses. However, few studies have comprehensively considered the interaction between joints and slit blasting, and there is a lack of quantitative research and analysis on slit blasting. Therefore, this study combined slit blasting, pouring model test blocks for explosion testing, and numerical simulations for auxiliary research. Finally, practical engineering applications were conducted. The results showed that the weakly constrained PVC material has a high instantaneous strength under impact and can achieve a good energy accumulation guidance effect. The joint angle has a significant impact on the isolation effect of explosion stress and crack propagation. The isolation effect of the explosion stress gradually weakened with an increase in joint angle. The smaller the angle, the more vulnerable the crack propagation direction is to the “traction” of the joint and tends to the trend of the joint, and the more serious the phenomenon of crack turning, deviation and bifurcation. The results show that the explosion energy propagates preferentially from the cutting seam direction, and the stress in the cutting seam direction reaches the peak value first. The energy in the cutting seam direction has a strong transmission ability and a directional fracture effect on the joints, and the application of weakly restrained slotted pipes in layered rock tunnel blasting construction has a good effect.