The creep behavior of rock shear seepage under different seepage-water pressures

The long-term compression–shear–seepage coupling of rock mass is a cause of many engineering geological disasters. This study aimed to explore the creep characteristics of rock mass under different seepage conditions. Based on the shear-creep–seepage test results of shale, the shear-creep–seepage model considering damage was constructed using a series connection of the elastomer (H), a nonlinear viscoelastic body with nonlinear function λ (NVEP), a viscoplastic body with seepage switch S (VPB), and a viscoelastic–plastic body considering damage (VEPB). The variation law of the model parameters was analyzed, and the results showed that the model effectively described the entire change process of rock-creep characteristics, notably the deformation law of the accelerated-creep stage. The correlation coefficient R^2 was greater than 0.98, and the fitting curve was highly consistent with the experimental data. Furthermore, the greater the seepage-water pressure, the smaller the shear stress applied in the corresponding test of each stage, and the greater the cumulative shear strain of each stage. Moreover, the seepage-water pressure had a damaging effect on the mechanical strength of the rock samples. The parameter values k_1 and λ were negatively correlated with seepage-water pressure and shear stress, whereas the parameter values k_2 and η _1 were negatively correlated with seepage-water pressure and positively correlated with shear stress. The results of this study can provide theoretical support for the research and analysis of rock-mass engineering stability under long-term seepage conditions.