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

Abstract

This article deals with numerical modeling of rock fracture under dynamic tensile loading and the related prediction of dynamic tensile strength. A special emphasis is laid on the influence of pre-existing natural microcrack populations as well as structural (artificial) cracks. For this end, a previously developed 3D continuum viscodamage-embedded discontinuity model is employed in the explicit dynamic finite element simulations of the spalling test. This model is capable of modelling the effect of natural microcracks populations always present in rocks as well as to capture the strain rate hardening effect of quasi-brittle materials. In the numerical simulations 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 effect of structural cracks with a good accuracy. According to the simulations, the effect of microcrack populations, modeled here as pre-embedded discontinuity populations, is weaker than the corresponding effect under quasi-static loading.