In the deep underground environment, with the high temperature and high confining pressure, the characteristics of hard rock, such as granite, will transform from brittleness to plasticity. Also, the mechanical behaviors and constitutive relations of the rock have great variation. For the rock under cyclic loading, its inner cracks are extended by stages, and the failing process is affected by cracks spatial distributions, mechanics behaviors and loading situations, which make the study more complex. In this paper, the triaxial compression test and Acoustic Emission (AE) monitoring test were used to analyze the failing mechanism of rocks. Also, the AE characteristics and their corresponding stress in each stage of failing process were described, so as to indicate the strength envelope of crack initiation, crack damage strength, peak strength and residential strength. At last, the relationship between AE characteristics and rock failing was obtained.
With the exploitations increasing by steps, the shallow resources are exhausted gradually in China, so many open-pit mines have to be faced with deep excavations. In this deep underground environment, with the high temperature and high confining pressure, the characteristics of hard rock, such as granite, will transform from brittleness to plasticity. A large number of scholars in the word have done a lot of researches on the failure mechanism of rocks at present. Xie et al. (2011) researched on the energy analysis for damage and catastrophic failure of rocks. Molladavoodi and Mortazavi (2011) analyzed the failure mechanism of brittle rocks with a damage based numerical method. Nicksiar and Martin (2012) gave a method to determine crack initiation in compression tests on low-porosity rocks. Ghazvinian et al. (2012) studied the failure mechanism of planar non-persistent open joints with PFC2D. Erarslan and Williams (2012) expounded the mechanism of rock fatigue damage in terms of fracturing modes. Peng et al. (2014) raised an empirical failure criterion for intact rocks. Although huge efforts have been done and mass information has been obtained on the failing mechanism of rocks under single loading, in order to acquire the particular failing mechanism of host rock, which is usually under complex loading environment, such as cyclic loading and confining pressure, the researches of rocks under cyclic loading are quite necessary.
