Study on Fracture Characteristics of Mode II Fractured Rocks Under Different Heat Treatments

In vigorously developing geothermal projects, in order to improve mining efficiency, it is necessary to explore the mechanism of rock failure in high-temperature environments. This study conducted compression experiments on pure type II fractured rocks subjected to heat treatment at different temperatures. The relationships between fracture toughness, crack propagation velocity, and fracture energy with heat treatment temperature were explored. By comparing the paths and initiation angles of crack propagation before and after aggregation at different temperatures, it can be found that granite is more prone to intergranular fracture after high temperatures. According to the relationship between energy and crack propagation rate, it was found that crack propagation velocity cannot be used to characterize fracture energy. The strain amplitudes of rock were analyzed using DIC technology, and it was found that the maximum strain value of granite at peak time was positively correlated with temperature, with a larger variation amplitude.