Numerical simulation for the influence of delay time on the rock fragmentation

Johansson et al. (2012) have investigated the influence of delay time on the fragmentation with a series of small-scale tests. Their results showed no distinct differences in fragmentation when the delays were in the time range of shock wave interactions compared to no shock wave interaction; Schill (2011) studied the influence of delay times on the blasting effect of two holes model with the LS-DYNA (Hallquist, 2007) computer code and the RHT (Riedel et al, 1999) material model and concluded that there was an effect of interacting stress waves. However this effect was local around the interaction plane, implying that precise ignition will not generate a dramatic increase in fragmentation contrary to what was proposed by Rossmanith. The results also indicated that longer delay times (in which the stress wave would have passed the neighbouring boreholes) also resulted in improved fragmentation.