Creep Damage Model Considering Viscoplastic Strain Rate and Energy Dissipation

ABSTRACT In the creep process of rocks, energy dissipation is the core driving factor of damage evolution. The initiation and propagation of microcracks within rocks, as well as the closure and penetration of pores, are all accompanied by irreversible energy dissipation, and the damage, in turn, affects the efficiency of energy storage and dissipation. Based on the principle of energy conservation, a brand‐new energy dissipation‐driven damage variable has been derived. Combined with the three parts of instantaneous elastic–viscoelastic–viscoplastic strain of uniaxial creep, the final creep model expression with damage is given. The model was verified through indoor triaxial creep tests, and the model parameters were identified by using the least‐squares method. The results show that the model curve has a high degree of agreement with the test curve, and the correlation coefficients are all above 0.90. Moreover, compared with the Nishihara model, it provides a more accurate description of creep damage to rocks. In addition, the sensitivity analysis of the model parameters has clarified the phased regulation rules of each parameter. The damage variables and models constructed in this study provide a solid physical foundation and high‐precision computational tools for the research of rock creep damage and have significant theoretical and engineering application value.