Compressive mechanical properties and anti-fracture mechanisms of anchored single-fissured granite using three-dimensional coupled GBM-FDM methodology

To investigate the anchorage anti-fracture effect of fissured granite, a numerical model representing the crystalline structure of anchored single-fissured granite was constructed using the discrete-continuous coupling (GBM-FDM) method. Uniaxial compression tests were conducted on both unanchored and anchored samples of single-fissured granite with a 45° inclination angle. The failure process of fissured granite under uniaxial compression and the anchorage anti-fracture effect of the anchor system on single-fissured granite were systematically examined from mesoscopic perspectives, focusing on force chain evolution and micro-crack propagation. The results indicated that the failure pattern of the unanchored sample under uniaxial compression exhibited significant propagation along the fissure tip region. In contrast, the internal fractures of the anchored sample were distributed more widely and uniformly compared to the unanchored sample. The force chain distributions within the anchored samples were more uniform, suggesting that the anchor structure enhances the stress distribution during the loading process, thereby effectively improving the load-carrying capacity. Additionally, the number of cracks in the anchored samples was lower, while the mean value of the force chain was higher, and the force chain value required to generate a single crack was greater in anchored samples than in unanchored ones at the same load level.