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.

Automated summary

The shock wave generated from underground blasting can cause severe catastrophe and irreparable destruction to adjacent underground and ground structures. Laboratory tests using explosive charges and cement mortar blocks were conducted to investigate the dynamic response of rock masses and adjacent underground openings to underground blasting. The findings show that both charge loading density and joint orientation significantly affect ground peak particle velocity (PPV) and peak strain at openings and rock masses. Increasing charge loading density or decreasing scaled distance results in a rise in peak strain of rock masses. Ground PPV is observed to clearly increase with higher charge loading density. The wave path, determined by the relative locations of the explosion source, measuring point, and joints, dominates the first peak strain of rock masses and ground PPV. The principal frequency of ground vibrations increases with higher joint orientation, while charge loading density has a slight impact on the principal frequency. These research findings contribute to a better understanding of blasting wave propagation in jointed rock masses and facilitate the stability assessment of aboveground and underground structures under underground explosions.