Investigation of the blast fragmentation using the mean fragment size and fragmentation index

An extensive multivariate analysis procedure for prediction of the blast fragmentation is presented. Several blasts performed in various mines and rock formations in the world are compiled and evaluated. Blast design parameters, modulus of elasticity, in situ block size are considered in the multivariate analysis. Two main approaches for prediction of blast fragmentation given in the literature are used for comparison. First, a mean fragment size prediction model is developed. Then fragmentation indices are determined for each blast and the fragmentation index prediction model is created using discriminant analysis method. Discriminant analysis played a key role during design stage of both models. The structure and prediction ability of the two models are compared and discussed. Models can be used separately or to complement each other. The models are applied to a wide range of test blasts. The models are not complex and suitable for practical use in mines.

► The fragmentation index prediction model is an alternative approach to mean fragment size prediction concept. ► Using the fragmentation index model, the fragmentation efficiency or expected mean fragment size interval can be calculated. ► Discriminant analysis technique is a useful tool to develop accurate fragmentation prediction models.