Abstract:
Aimed to study the characteristics of strength and deformation along with acoustic emission under cyclic loading, uniaxial and triaxial cyclic loading-unloading compression tests on granite were carried out using MTS815 system. Test results show that the "concave-upward" phenomenon of deviatoric stress-axial strain curves and the "migration" of hysteresis loops under the triaxial cyclic compression are not so obvious as those under the uniaxial compression. The peak strength and peak strain have a good linear relationship with confining pressure. During the uniaxial and triaxial compression tests, the elastic modulus and the Poisson's ratio of the first five cycles increase with the increase of cycle times, while the elastic modulus decreases at the last loading-unloading cycle. In the uniaxial cyclic test, the specimen demonstrates columnar splitting failure, but it shows obvious shear failure during the triaxial cyclic test. The AE ringing counts during the last loading-unloading cycle in the triaxial test are significantly less than those in the uniaxial case. Besides, a platform can be detected at each stage of the damage duration curve for the uniaxial cyclic loading, whereas it is not obvious in the triaxial test, implying that the damage of rock specimen experiences a show growth.