A grain-based discretized virtual internal bond (GB-DVIB) model for modeling micro-cracking of granular rock

The meso-structure of rock essentially affects its macroscopic mechanical behaviors. Based on the discretized virtual internal bond (DVIB) model, a grain-based DVIB (GB-DVIB) model is developed to investigate the gain-scale micro-cracking process. A meso-structure generation method for granular rock is proposed within the framework of DVIB. By this method, mineral grains, grain-boundaries and voids can be generated conveniently. Based on the relationship between macro and micro-parameters in DVIB, the mechanical parameters of meso-structure obtained by experiments can be employed to calibrate the micro-bond parameters directly. The effect of mechanical parameters of meso-structure, grain size and porosity on the macroscopic mechanical behavior is investigated, which provides a valuable reference for the application of GB-DVIB. The intra-granular and inter-granular cracks both can be reproduced by the method. A three-point bending test and an asymmetric compressive test of granite samples are simulated. The simulated micro-cracking process and macro-failure pattern are consistent with the experimental observation. The GB-DVIB provide a convenient and effective tool for researching the gain-scale micro-cracking process of granular rock.