Investigation of the relationship between fragmentation and brittleness of rock, in particular class II rock type

Akinbinu, Victor Abioye
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The aim of this research is to investigate the relationship between fragmentation and brittleness of rock by taking into account the influence of the Class II characteristic behaviour of the rocks have on this relationship. Fragmentation of rock under compressive failure depends on its self-sustaining failure and the energy available in the post-failure region to shatter the rock. The fragmentation produced under this condition depends to a large extent on the energy available to cause fragmentation and on the brittleness of the rock. From review of the literature, it appears that no research has attempted to link brittleness and fragmentation. Rock failure under dynamic loading conditions, such as in blasting, rockbursts, crushing, and milling, as well as during conventional unconfined compressive strength testing of rock specimens and the subsequent fragments size distribution is a little-understood phenomenon. This relationship will be helpful in the solution to many practical mining and civil engineering problems. This includes the prediction of optimal fragmentation and the design of stable structures as a result of dynamic processes particularly associated with fragmentation. The research carried out involved the analysis of rock parameters determined from different rock Classes (Class I and Class II) under destructive tests using a soft testing machine and a closed loop servo-controlled testing machine (stiff machine). The tests were conducted according to ISRM suggested methods at the Genmin Laboratory, Wits University while the post-failure stress-strain curves estimation were done using a closed loop servo-controlled testing machine at the Rock Engineering Department at Aalto University Finland. In addition, non-destructive tests were conducted with the output being monitored using a dual-beam cathode ray oscilloscope. From the destructive tests, the static parameters were determined