• Long-term creep tests on Beishan granite under uniaxial compression reveal that specimens fail under sustained loads above a threshold, with durations ranging from 839 to 1204 days, while a specimen at 60 MPa survived over 1650 days.
• A lower envelope of driving stress-ratio for crystalline rocks approaches approximately 0.45 over infinite time, providing a critical reference for long-term strength assessment.
• Both transient creep strain and steady-state creep rate increase exponentially with axial stress, while the steady-state creep strain contribution remains constant at about 82.53%.
• A novel damage-based creep model accurately predicts the accelerated creep phase, enhancing the reliability of long-term stability evaluations for engineering structures such as deep geological repositories.