Characteristics of stress, crack evolution, and energy conversion of anchored granite containing two preexisting fissures under uniaxial compression

In this study, uniaxial compression experiments were conducted of granite specimens containing two preexisting fissures to investigate the effect of bolts on mechanical behaviour, crack arrest, and energy absorption. Different mechanical properties of the granite specimens with and without bolts were analysed according to the axial stress–strain curves. Then the behaviour of the crack evolution during the loading process, as well as the images of granite specimens when they were destroyed, was observed and analysed using the digital image correlation (DIC) method. In addition, various forms of energy at the peak load, including the total strain energy, elastic energy, and dissipative energy, were compared with one another. The experimental results show that (1) bolts have a positive effect on strength enhancement and deformation control, and the effect is related to the joint inclination angle; (2) there are two crack arrest effects: controlling the rate and direction of the propagation of tensile wing crack (type I) and preventing the coalescence of shear crack (type II) from developing through upper and lower preexisting fissures; and (3) the bolt increases the energy absorption but does not change the tendency of the total strain energy with joint inclination angles. These results contribute to the understanding of bolt support in deep-rock engineering.