Propagation characteristics of blast-induced shock waves in a jointed rock mass

The propagation characteristics of blast-induced shock waves in a jointed rock mass have been monitored and studied. Accelerometers were set up on a rock surface along three lines, at 0 degrees, 45 degrees and 90 degrees with respect to the orientation of the predominant joint strikes. Cylindrical charges were detonated in a charge hole, and ground accelerations in both vertical and radial directions at various points on the rock surface were recorded. Results show that rock joints have significant effects on the propagation characteristics of blast-induced shock waves. The amplitude and principal frequency of shock waves attenuate with the increase of distance from the charge centre, and the increase of incident angle between the joint strike and the wave propagation path. The measured data were compared with the empirical equations of shock wave attenuation proposed by other authors. The mechanism of rock joint effect, the attenuation of shock waves in relation to the propagation distance, the charge weight and the incident angle, are discussed in this paper. (C) 1998 Elsevier Science Ltd. All rights reserved.