Effect of High Temperature Heat Treatment on Initiation and Failure Characteristics of Brazilian Crack in Granite

In order to study the influence of high temperature on crack generation, propagation and through-process, the Brazilian splitting test was carried out on granite treated at 25–1 000 ℃, and the evolution of the principal strain field of the sample in the splitting process was tracked and analyzed by digital image correlation（DIC）, and the results showed that: 1) With the heat treatment temperature increases, the degree of bending at the macroscopic fault after granite splitting failure intensifies, and the failure mode changes from tensile failure to tensile and shear mixed failure. 2) Under different high-temperature splitting conditions, granite generally underwent the elastic-plastic-failure stage. At 25 ℃, the specimen undergoes brittle failure, plastic deformation and failure stage is extremely short; at 100–500 ℃, the main strain accumulates significantly in the plastic stage, and the failure stage is very short, and it is still brittle fracture; at 600–1 000 ℃, the failure stage is obvious, and the failure mode changes to ductile failure.3) With the increase of temperature, the brittleness of granite weakens, the ductility of granite gradually enhances, the Y-shaped rupture disappears, the corresponding load level of PE-F at the elastoplastic transition point decreases linearly.