Failure behavior of the thermal treated granite under triaxial cyclic loading–unloading compression

Abstract

Because after being thermal treated, the failure behaviour of granite has an adverse influence on the safety and stability of the HLW disposal repository, its stress–strain curves, elastic modulus, Poisson’s ratio, plastic strain, dissipated energy and failure characteristic were analyzed by conducting and simulating triaxial compression test. According to the results, it was indicated at the initial elastic stage, that indexes above and accumulated AE count slightly increased with cyclic loading processing when T = 25 and 300 °C, suggesting less damage was caused. However, when T = 600 °C, the damage was caused immediately once applying cyclic loading. In the initial stage, under the function of triaxial cyclic loading–unloading, material grains were rearranged. Because of the more complexity of the failure modes of cyclic loading than that of monotonic loading, the rougher shear surface was formed, leading to a higher residual strength. When T = 600 °C, continuous development of micro-crack during uniaxial cyclic loading deteriorates the peak strength. The mechanical behavior of thermal treated granite under triaxial compression was investigated by experiment and numerical simulation. And found that the micro-cracks continuous increases under unloading process, which lead to the reduction of the peak strength