Mechanical properties and energy evolution of jointed rock specimens containing an opening under uniaxial loading

To investigate the impact of an opening and joints with different inclination angles on the mechanical response behavior, the energy evolution characteristics, and distribution law of granite specimens, uniaxial loading tests were performed on the parallel jointed rock samples with an opening. Results indicated an initial decreasing trend of the strength and deformation parameters, which later increases with increased inclination angle, reaching minimum values when the inclination angle is 45°. Evolution curves of the elastic strain energy and dissipated energy with strain of the samples showed step-like gradual mutation characteristics. The peak total energy, peak elastic strain energy, peak dissipated energy, and total input energy during the failure of the samples showed significant nonlinear characteristics with increasing inclination angle. The opening and joints as well as the change of the inclination angle had significant influences on the proportion of the elastic strain energy of the samples prior to the peak, resulting in the difference of the distribution law of input energy. Moreover, the energy mechanism of the sample failure was discussed. Results showed that the energy release was the internal cause of the sudden destruction of the entire rock mass.