Abstract:To accurately investigate characteristics of rocks in the non-linear accelerated creep stage, a novel non-linear viscoelastic-plastic creep model of rocks was established based on the memory-dependent derivative (MDD) theory and generalized to the three-dimensional (3D) space. The model was established by connecting the memory-dependent (M-D) dashpot, Hooke solid, and non-linear viscoplastic body formed by parallel connection of the plastic element and M-D dashpot in series. Under low stress, the Hooke solid and M-D dashpot can describe both the instantaneous and isokinetic creep characteristics of rock; when the stress exceeds the long-term strength of the rock, the non-linear viscoplastic body can manifest the non-linear accelerated creep characteristics of rocks. Creep data pertaining to shale, greenschist, and clay were used to compare the accuracy of the M-D creep model, fractional creep model, and viscoelastic-plastic creep model. The results show that the goodness-of-fit of the proposed model is better than other models in expounding creep deformation of rock and soil mass, with a particular advantage in characterizing non-linear creep of a rock and soil mass.
