Uniaxial accelerated creep constitutive model of rock considering damage and hardening

Although significant progress has been made in the study of rock creep deformation, major challenges remain in accurately characterizing its nonlinear features and the mechanisms governing accelerated creep. Existing constitutive models often fail to capture these complexities, particularly the coupled effects of damage accumulation and hardening during creep. In this study, a uniaxial accelerated creep constitutive model incorporating both damage and hardening is proposed, based on the Rabotnov creep damage law and combined with hardening and damage theories. The results indicate that under failure stress, the rock damage variable increases slowly at first, then rises sharply, approaching unity at the time of failure. The introduction of a hardening function confirms the presence of hardening phenomena during the creep stabilization stage, accurately characterizing the extent of damage and hardening effects in rocks. The proposed model effectively captures rock creep behavior across different stress levels, with correlation coefficients exceeding 0.90, and the model can reliably predict the deformation patterns of rocks under failure stress. The results are crucial for the stability of surrounding rocks in underground engineering and prevention of geological disasters.