Fragmentation and heave modelling using a coupled discrete element gas flow code

Experimental evidence indicates that a large percentage of the crack development and subsequent fragmentation and heave in the blasting process is due to the effects of the high pressure gas generated by the explosive in the blasthole. An explicit finite/discrete element code has been developed to dynamically model stress field development, crack generation and crack growth as well as the motion and stacking of the rock fragments. Cracking in the current model is limited to failure under tension (Rankine). This failure is due to both the stress and the gas flow which is treated by coupling the discrete element porosity field to a finite volume gas flow model. Several examples are discussed which show striking qualitative differences between blasting with stemming to contain the gases in the blastholes, and without stemming.