Evolution of Physical and Mechanical Properties of Granite after Thermal Treatment under Cyclic Uniaxial Compression

The combined effects of thermal and cyclic loading result in complex mechanical behavior in engineering rock masses. The study of the physical and mechanical properties of these rock masses is of great importance for improving the stability and sustainability of structures built on thermally treated rock masses. In order to understand the failure mechanism, uniaxial compression tests and cyclic loading and unloading tests were conducted on granite specimens that had undergone thermal treatment at various temperatures. The test results indicate that the density and P-wave velocity of the specimens decrease while the degree of damage increases after thermal treatment. The compressive strength and elastic modulus of the specimens generally decrease as a result of thermal treatment, although thermal hardening does occur within the temperature range of 200–400 °C. The dilatancy characteristics of the specimens change with the treatment temperature, and they are more prone to shear dilation under external loading. Furthermore, the failure mode of the specimens transitions from brittle to ductile failure as the treatment temperature increases. The combination of thermal treatment and cyclic loading causes the rock fragments to become looser and finer following specimen failure.