Creep Characteristics and Model of Key Unit Rock in Slope Potential Slip Surface

The creep characteristics of the key unit rock in a slope potential slip surface play an important role in the evolution of slope slip. In this research, a systematic restrictive shear creep experimental study was conducted to investigate the restrictive shear creep characteristics of the key unit rock in a slope potential slip surface. A new plastic nonlinear model (PFY model) was developed to characterize the progressive-failure creep characteristics reflected in the process of the restrictive shear creep of rock. A variable-parameter restrictive shear creep model was established to reflect the progressive-failure characteristics and describe the whole process of restrictive shear creep of the rock and the two failure mechanisms of the rock, which can provide the reference base for the prediction of the time of shear creep failure of the rock. The constitutive equations characterizing the shear creep characteristics of the rock were established, and the methods to solve model parameters were determined. In addition, according to the obtained experimental data, the model parameters were solved, and the theoretical curves of the model were fitted with the experimental curves. The new model was validated, and the sensitivity of the model parameters to creep-failure time were analyzed. The results show that the overburden pressure and the maximum creep strain of the key unit rock in a slope play a leading role in the progressive failure and instability of the rock, and the shear creep rate with time fits the power function well. The theoretical curves of the new model match well with the experimental curves, and the differences in the creep-failure time between the model calculation values and the experimental values are small, which indicates the new model is appropriate in describing the creep characteristics of the rock. For the shear creep-failure time, the viscous coefficient η_2 is the most sensitive, the accelerating point strain γ_a comes next, and the progressive-failure coefficient β is the least sensitive