Rock slopes in reservoir drawdown zones are subjected to the coupled effects of cyclic water‐level fluctuations and sustained in situ stress, which significantly influence their long‐term stability. In the Three Gorges Reservoir, seasonal water‐level variations induce repeated water pressure loading–unloading, accelerating time‐dependent deformation and damage evolution of bank rocks. However, the creep behavior of sandstone under cyclic water pressure remains insufficiently understood. In this study, triaxial creep tests were conducted on red sandstone from the Three Gorges Reservoir drawdown zone under cyclic water pressure (0–0.3 MPa) and different axial stress levels. The results indicate that cyclic water pressure causes cumulative mechanical degradation, leading to reductions in strength and stiffness and progressive irreversible deformation. The creep behavior is jointly controlled by stress level and hydraulic cycling, with a critical stress threshold identified at ~80% of the peak strength, beyond which accelerated creep and failure occur. The classical Burgers model accurately captures primary and secondary creep but fails to describe the accelerated creep stage induced by damage accumulation. To address this limitation, a damage‐modified Burgers model incorporating a strength‐based damage variable is proposed. The modified model successfully reproduces the full creep process with high fitting accuracy ( R 2 > 0.992). These findings provide a theoretical basis for long‐term deformation prediction and stability assessment of reservoir bank slopes subjected to cyclic hydraulic–mechanical coupling.
He et al. (Thu,) studied this question.