Characteristic Fracture Pattern and Fragment Size Distribution in Rocks due to Stress Waves in Blasting

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Rock fragmentation by explosive is the preferred method of extraction of valuable minerals. It is also the preferred method for most civil excavation operations. However, despite overwhelming prevalence of the practice, accurate prediction of blast results for a given explosive-rock combination has remained exceedingly difficult, as it involves a very large number of variables whose effect on blast results is yet to be quantified. Prediction of fragment size distribution and its control would be a very significant improvement in all mining and quarrying operations. They affect all 'downstream' operations such as loading, crushing, grinding and milling. These have direct bearing not only on the economics of the operations but also on their safety. It is not possible at this time to predict all aspects of a large blast, but incremental improvement in our understanding of interrelationship between explosive type, blast design and relevant properties of the target rock would go a long way to meeting the ultimate objective. Considerable progress in our understanding of the blasting process has been made however during the last few decades by several research groups including this author's own in identifying the key variables. One of these is the link between fracture process due to explosive action in the borehole and the eventual fragment size distribution in a blast. However, systematic investigation of all the interconnecting parameters in large-scale operations is not feasible, hence the need for controlled tests and advanced analysis on well characterized rocks and explosives. This proposed research is aimed at developing one such 'building block' in our attempt to develop a predictive and reliable fragment prediction model.