It has been proposed that blasting today is still more of an art than a science, with engineers relying mostly on personal experience and methods of trial and error to optimise blast designs. One of the major factors inhibiting the development of the science of blasting has been the lack of measurement techniques, or the means of evaluating blast performance in quantitative terms. This thesis presents a technique, developed by the author, of quantitatively assessing blast performance through the study of ground vibrations.
Since this technique does examine blast performance in terms of the strainwaves produced, the relevance of strain energy to overall fragmentation is important, and is addressed on several occasions throughout the thesis.
To the best knowledge of the author, no successful attempt had been previously made to monitor ground vibrations in the immediate vicinity of a full scale production blast, requiring the characterisation and development of suitable instrumentation for such purposes.
Analysis techniques have been developed which enables the initiation sequence (and precise initiation times) of the individual charges in a blast to be derived from vibration data.
These instrumentation and analysis techniques were used to study blast performance at a variety of sites, identifying the occurrence of 'charge malfunctions' as a problem of significant proportions. Several mechanisms by which these malfunctions may occur have been postulated.
The blast vibration monitoring technique was also used to examine the interaction between certain blast design variables, specifically concentrating on the following features or influences; charge length; point of initiation; charge type; and explosive strength reduction techniques.
A strainwave simulation model, based on an algorithm originally proposed by Starfield (1966), was developed and used to further investigate various aspects of the blasting process, and aid in the interpretation of vibration data.
The investigative techniques developed during this research programme were applied to the assessment of bla-.t performance at the El Soldado mine in Chile. The ability to use these techniques to identify and diagnose faults in blast design was clearly demonstrated during the El Soldado study, proving them to be a simple and efficient means of improving blast performance.