Modeling Full‐Stage Rock Creep: A Perzyna Viscoplastic Approach Incorporating Damage and Strain Energy Theory

Under high‐level stress, the internal damage of rock accumulates over time, leading to significant nonlinearity in creep. However, traditional linear element combination models struggle to describe the creep behavior of rock in the accelerated creep stage. The creep mechanism is analyzed from the perspective of internal energy, and a new creep model is constructed based on strain energy theory by integrating Perzyna′s viscoplastic theory and the Nishihara model. This model can accurately characterize the full‐process curves of the three creep stages: primary creep, steady‐state creep, and accelerating creep. The one‐dimensional and three‐dimensional creep constitutive equations of the model are derived. The results show that the nonlinear viscoelastic‐plastic rheological model has a correlation coefficient exceeding 0.95 with creep test data. It can precisely describe the primary and steady‐state creep of rock under low stress, and more accurately reflect the accelerating creep characteristics under high stress. The established creep model overcomes the defect that the Nishihara model cannot describe accelerating creep. Meanwhile, a viscoplastic strain expression based on Perzyna′s viscoplastic theory is established to more accurately characterize accelerating creep. The research findings provide a new approach for studying the creep fracture process of rock.