Research on the macro-meso failure characteristics of single jointed granite under uniaxial compression.

The existence of joints has a significant influence on the failure characteristics of rock mass. In this paper, based on two-dimensional (2D) particle flow code (PFC2D), uniaxial compression tests are conducted on the granite specimens with a single joint at different dip angles to investigate the evolution laws of macroscopic and mesoscopic failure characteristics. The results demonstrate that macro-mechanical characteristics of rock are influenced by the dip angle of the joint. The peak strength, peak deformation, and elastic modulus are positively correlated with the dip angle of the joint, while Poisson's ratio is negatively correlated. With the increase in the dip angle of the joint, mechanical characteristics of rock finally tend to be consistent with those of an intact rock specimen. In addition, when the dip angle of the joint is small, the rock specimens show obvious plastic characteristics before reaching the peak and there are multiple peaks being found on stress–strain curves. As the dip angle of the joint rises, the number of stress fluctuations gradually decreases and the curve near the peak becomes straighter and sharper. Moreover, the rock specimens exhibit more obvious brittle characteristics. The increase in the dip angle of the joint enhances the tendency of azimuth angle of microcracks to develop along the direction of the maximum principal stress. In the meanwhile, the distribution of the azimuth angle is gradually similar to that of microcracks in the intact specimen. With the rise of the joint dip angle, the failure modes of rock specimens change from tensile failure to shear failure to tensile failure, and finally tend to be consistent with the intact rock. [ABSTRACT FROM AUTHOR]