Coupling Mechanism of Wall Protection Blasting and Notched Blasting

In order to improve the blasting forming accuracy and the protection of surrounding rock under deep and complex geological conditions, comparative experiments of protective blasting and protective notched-coupling blasting were conducted using a digital laser dynamic caustic experimental system and PMMA specimens. The crack propagation mechanisms and mechanical response characteristics of the two blasting modes were systematically investigated. The results show that, in the protective notched-coupling blasting, the main crack propagates stably along the preset notched direction, demonstrating an excellent directional control effect. Meanwhile, the secondary peak value of the crack-tip stress intensity factor is significantly higher than that of the single protective blasting, indicating a stronger dynamic stress concentration effect. The notched-coupling blasting also exhibits a higher overall crack propagation velocity with slower attenuation at later stages, reflecting enhanced persistence and stability. In addition, this blasting mode effectively reduces the length and number of cracks on the protected wall side, thereby providing better rock-mass protection. Overall, the protective notched-coupling blasting optimizes crack propagation behavior and improves the directionality and energy utilization efficiency of blasting through the combined mechanisms of notch guidance and energy re-concentration. These findings provide theoretical support and technical guidance for precision blasting design and engineering applications in deep rock masses.