Numerical modelling of dynamic spalling test on rock with an emphasis on the influence of pre-existing cracks

This article deals with numerical modeling of rock fracture under dynamic tensileloading and the related prediction of dynamic tensile strength. A special emphasis is laid on theinfluence of pre-existing natural microcrack populations as well as structural (articial) cracks.For this end, a previously developed 3D continuum viscodamage-embedded discontinuity modelis employed in the explicit dynamic nite element simulations of the spalling test. This modelis capable of modelling the eect of natural microcracks populations always present in rocks aswell as to capture the strain rate hardening eect of quasi-brittle materials. In the numericalsimulations of spalling test on Bohus granite, it is shown that the model can predict the pull-pack velocity of the free end of the intact rock sample and the eect of structural cracks witha good accuracy. According to the simulations, the effect of microcrack populations, modeledhere as pre-embedded discontinuity populations, is weaker than the corresponding eect underquasi-static loadin