Failure Process of Granite

The initiation, development, and coalescence of cracks when a rock specimen is loaded have been studied by various researchers. The current consensus is that such complex process is however not yet fully understood. In the present study, the problem has been revisited by carrying out extensive testing on granite specimens. Each specimen was loaded under uniaxial loading condition to various load levels in both prepeak and postpeak ranges. After unloading, the crack patterns were printed onto the surface of a piece of resin. The images of the patterns were then captured using a digital camera through optical microscope or scanning electron microscope. Statistical analyses on these images were then carried out using an image analysis software. The study focuses on the cracking behavior of the various mineral components of the granite and their respective roles in the failure process. In addition, a numerical model was developed to simulate the test results and parametric study was carried out to investigate the effects of various factors (heterogeneity index, C/T ratio, grain arrangement, and grain size, etc.) on the failure behavior of the granite. The study has provided insight on the development of cracks, especially in the postpeak range. A better understanding on the roles of the major minerals in failure process of the granite has been achieved.