Blast Densification Method: Sound Propagation and Estimation of Psychological and Physical Effects

Abstract

Experimental results on the propagation of blasting sounds from underground explosions for preventing liquefaction of ground are described. Psychological and physical effects of blasting sounds are estimated by comparison with previous studies on the effects and evaluation of continuous low-frequency sounds. The blasting sounds generated by underground explosions were impulsive low-frequency sounds, which predominantly involved frequencies of several Hz. Frequencies above 100 Hz tended to attenuate to a greater degree during propagation from the blasting area. Sound pressure levels at frequencies above 20 Hz exceeded the hearing threshold level as well as the threshold for rattling of building fittings for low-frequency sounds even at a point about 400 m distant from the blasting area. To predict the attenuation of the blasting sounds and estimate the appropriate distance for reducing the possibility of complaint, results of numerical calculations by the parabolic equation method together with meteorological data are shown.