Failure Behavior of the Thermal Treated Granite under Triaxial Cyclic
Loading-unloading Compression
Abstract
The failure behavior of thermal treated granite under triaxial tiered
cyclic loading-unloading compression has a significant effect on the
safe and stable operation of HLW disposal repository. Therefore, the
stress-strain curves, elastic modulus, Poisson’s ratio, plastic strain,
dissipated energy and failure characteristic of the thermal treated
granite specimens under triaxial compression were analyzed by experiment
and numerical simulation. The results indicate that the elastic,
Poisson’s ratio, axial plastic strain, dissipated energy and
accumulative AE counts slightly increase with cyclic loading at initial
loading and elastic deformation stage when T = 25 and 300°C, which means
that less damage was induced by cyclic loading. However, damage occurred
once cyclic loading was applied when T = 600°C. Radial strain even
showed compressive characteristic in the initial stage, which indicates
that grains adjustment occurred under triaxial cyclic loading-unloading
compression. And, the compressive characteristic is more obvious with
the increase of temperature or the decrease of confining pressure. The
failure modes under triaxial cyclic loading are more complicated than
that under triaxial monotonic loading, which make the shear plane
rougher. Therefore, the residual strength is higher than that under
monotonic loading. When T = 600°C, micro-crack continuously increases
under uniaxial unloading and loading process, which result in a decrease
of the peak strength under cyclic loading compared with that under
monotonic loading.