Modelling micro-cracking behaviour of granite during direct tensile test using cohesive GBM approach

We employed a cohesive grain-based model (GBM) to investigate the mechanical behaviour and micro-cracking response of Neuhauser granite under direct tensile loading. The microstructural properties of Neuhauser granite were incorporated into the numerical model, and hourglass-shaped specimens were generated based on the geometrical configuration of specimens. We proposed an alternative calibration procedure, and the numerical observations revealed that the cohesive GBM could accurately reproduce the failure behaviour of physical specimen. At the same time, the conventional GBM failed to return a reliable output. The calibration procedure was augmented by examining the impacts of the random distribution of minerals and tensile loading rate on the fracture behaviour of GBM specimens. Besides, pre-cracked granite was generated to investigate the influence of pre-existing cracks on mechanical and fracture behaviour. By increasing the flaw inclination angle, the peak tensile strength of both single and double flaw specimens was increased. The micro-cracks initiated from flaw tips and extended horizontally towards the side of specimens. At low flaw inclination angles, the macroscopic tensile fracture was almost identical to that of intact rock while the fracture pattern was different at high flaw angles.