Experimental study of the dynamic responses of surrounding jointed rock masses and adjacent underground openings and induced ground vibrations subjected to underground explosion

The shock wave generated after underground blasting might lead to severe catastrophe or irreparable destruction of adjoining underground and ground structures. To investigate the dynamic response of rock masses and adjacent underground openings and induced ground vibrations subjected to underground blasting, a sequence of laboratory tests was implemented with explosive charges and cement mortar blocks. The results show that not only the charge loading density but also the joint orientation affect the ground peak particle velocity (PPV) in a significant way, as well as the first peak strain at the neighbouring opening and in the surrounding rock masses. The first peak strain of the rock masses has a rising tendency with increasing charge loading density or decreasing scaled distance. The PPV on the ground clearly increases with increasing charge loading density. The first peak strain of the rock masses and ground PPV are dominated by the wave path, which is determined by the relative locations of the explosion source, measuring point and joints. The principal frequency of ground vibrations shows an increasing trend with increasing joint orientation, while the charge loading density slightly impacts the principal frequency. These research findings could enhance the comprehension of blasting wave propagation through jointed rock masses and contribute to the stability evaluation of aboveground and underground structures subjected to underground explosions.