Hybrid finite–discrete element modelling of rock fracture process in intact and notched Brazilian disc tests

Abstract

A hybrid finite–discrete element method is proposed to model the rock fracture behaviour under various loading rates. Three fracture models are proposed to predict the fracture initiation and propagation for modelling the transition from continuum to discontinuum. The modelling transition from continuum to discontinuum makes the hybrid method superior to the traditional continuum-based finite element method and discontinuum-based discrete element method. Moreover, the hybrid method considers the effect of the loading rate by implementing an empirical relationship between the static strengths and the dynamic strengths derived from the dynamic rock fracture experiments. Then, the Brazilian tensile strength tests are modelled to calibrate the proposed method under various loading rate, and demonstrate its ability in modelling the dynamic rock behaviours. The Notched Brazilian Disc tests are modelled to illustrate the capabilities of the proposed method in modelling different fracture modes. The hybrid finite element method has well modelled the stress propagation, fracture initiation and propagation, even the pure mode I, pure mode II and mixed-mode I–II fractures. It is concluded that the hybrid finite element method is superior to the continuum-based finite element method and discontinuum-based discrete element method in modelling the fracture behaviours of rock under various loading rates.