Experimental study of blasting wave propagation in jointed rock mass and vibration reduction effect of barrier holes

Abstract

Abstract Blasting in underground rock opening could generate shock waves, propagating in surrounding rock mass and possibly leading to damage and instability of surrounding underground structures. Barrier holes are widely used in blasting vibration reduction. However, characteristics of blasting wave propagation in jointed rock masses have not been well determined, and the understanding of effect of barrier holes on vibration reduction is still at its infancy. To investigate the blast-induced wave propagation in jointed rock masses and vibration reduction effect of barrier holes, laboratory explosion tests were performed with the super dynamic strain test system and vibration monitor system. Results showed that the joint orientation has significant effects on the first-peak compressive strains in surrounding rock mass and adjacent opening. First-peak compressive strain of surrounding rock mass increases with decreasing scaled distance. The first-peak compressive strain on the wall of the adjacent underground opening is dependent on the characteristics of the adjacent underground opening. In addition, the dynamic responses of the surrounding rock mass are determined by the combined influence of the joint dip angle and location. The experimental results also indicated that barrier hole diameter has great effects on first-peak compressive strains of adjacent underground opening and the vibration-isolation rate of measuring points before and after barrier hole screen. With increasing barrier hole diameter, first-peak compressive strains and peak particle velocities (PPVs) significantly decrease and vibration-isolation rate of measuring points before and after barrier hole screen increases, indicating the vibration reduction effect of barrier hole increases. The findings in this paper could facilitate better understanding blasting wave propagation in jointed rock mass, and be helpful in vibration control of engineering explosions.