Scaled-distance relationships for chamber blast accidents in underground storage of explosives

Common approaches in practice to predict underground explosion-induced stress wave intensity are based on some empirical formulae. Those empirical formulae were obtained by different researchers based on their testing data at various sites. They can predict the peak particle velocities (PPV) and / or peak particle accelerations (PPA) of propagating stress wave at various locations. They usually include the effect of explosion loading density in terms of a decoupling factor, but do not take into consideration the effects of other explosion conditions, such as the charge chamber geometry, explosive location and distribution. In this paper, a previously calibrated numerical model is used to perform parametric calculations to investigate the effects of underground explosion conditions on stress wave propagation and damage at a granite site. Based on the numerical results, some formulae, which include the effects of various explosion conditions, are derived to predict peak particle acceleration (PPA), peak particle velocity (PPV) and principal frequency of stress wave in the granite mass. The proposed formulae are also compared with the empirical formulae obtained from blasting tests conducted at the site under consideration.