The characteristics of creep deformation and time to failure of deep hard rock are important for predict time-dependent disasters. Based on the short-term compression and long-term single-stage creep tests under true triaxial stresses, the characteristics of creep deformation and time to failure of Beishan granite subjected to different intermediate principal stress ( $\sigma _{2}$ ) and deviatoric stress ( $\sigma _{1}$ - $\sigma _{3}$ ) were studied. The prediction formula of time to failure was established for hard rock, considering the effect of $\sigma _{2}$ . The test results show that the time to failure of rock samples increases with the decrease of the stress-strength ratio (SSR = ( $\sigma _{1}$ - $\sigma _{3}$ )/( $\sigma _{\mathrm{p}}$ - $\sigma _{3}$ )) under the same $\sigma _{2}$ and $\sigma _{3}$ conditions. In addition, the steady creep rate of rock sample is affected by the stress-strength ratio of the over-stress ( $\Delta$ SSR = ( $\sigma _{1}$ - $\sigma $ cd)/( $\sigma _{\mathrm{p}}$ - $\sigma _{3}$ )). With the increase of the $\Delta $ SSR, the steady creep rate of rock samples increases. With the increase of $\sigma _{2}$ , the $\Delta $ SSR of rock samples decreases under the same SSR, therefore, high $\sigma _{2}$ increases the time to failure of rock samples. Based on the scientific understanding of the characteristics of small deformation and time to failure of Beishan granite, a 3D Nonlinear Creep Model of Beishan Granite under true triaxial stress is proposed. The model can reflect the viscoelastic-plastic characteristic and damage-accelerated creep process of Beishan granite under true triaxial stress. The applicability of the proposed model is verified by comparing with the creep test data.
