GROUND AND STRUCTURAL RESPONSE DUE TO BLASTING.

Controlled studies of the damaging effects of blasting vibrations have indicated that peak particle velocity is the best index for blasting vibration damage to residential structures. Accordingly, research in this area has been principally concerned with predicting peak particle velocities. However, a response spectrum of blast-induced ground motions is more broadly applicable than peak particle motions for determining the damage potential of blasting vibration because the response spectrum pertains to the whole frequency range rather than the limited frequency range represented by the velocity bound. To be useful, the response spectrum of a blasting vibration must be easily predictable. Therefore, a method was developed to predict response spectra from preliminary blasting and geological information. The field studies necessary to generate the basic data involve quarry, tunnel, and shaft blast with maximum explosive charges per delay ranging from 2. 36 lb. (1. 07 kg) to 19,600 lb. (8900 kg). To relate the response spectrum of blasting vibration to actual damage, response-spectrum bounds were calculated from the basement wall acceleration- and velocity-time histories resulting from blast which damaged one- and two-story structures.