ABSTRACT
A critical analysis is given of vibration damage models based upon simple charge weight scaling laws that have been modified in an attempt to account for the near-field influence of charge length. It is shown that such simple models are significantly flawed since they do not correctly account for the charge length or realistically account for the known blast wave radiation pattern. For example, these models fail to predict a dominant vibration component which is a vertically polarised shear (SV) wave. An analytical vibration model is developed to account for the charge length and radiation pattern as well as a finite velocity of detonation. The results of the analytical model compare favourably with a Dynamic Finite Element Model (DFEM). Both models clearly show that it is invalid to assume any simple relationship between vibration and strain for waves radiating from a blasthole, even in the very far field. It is also shown that traditional Seed Waveform modelling employing vibration waveforms measured from short (elemental) charges cannot yield a realistic vibration output for the entire blasthole; an alternative method is suggested.
