Direct shear creep tests have scarcely been used for long-term creep behavior studies of landslides in the Three Gorges reservoir area. In this study, based on field investigations and monitoring of the Huangtupo Landslide, direct shear creep tests were performed on the sliding zone soil of Riverside Slump #1, and the creep characteristics of sliding zone soil after varying cycles of reservoir water level fluctuation were studied. Using the creep results, the Mohr-Coulomb parameters were obtained by numerical simulation, and the deformation pattern of the reservoir landslide was analyzed. The results show that the direct shear creep of sliding zone soil can mainly be divided into stages of attenuation creep and steady-state creep. Under the same shear stress, with the increase of loading-unloading cycles N, the soil's strain and shear strain rate in the sliding zone decreased accordingly, and the long-term strength gradually improved. As the shear stress increases, the shear strain rate increases and the creep of the soil in the sliding zone has an obvious time effect. Our numerical simulation results showed good agreement with both the landslide deformation monitoring data and direct shear testing data. The Burgers model is suitable for describing creep deformation of landslides under fluctuating reservoir water levels. Under high shear stress, the fitted curve showcased both attenuation and constant velocity characteristics. Numerical simulation and burger model can reflect the direct shear creep test characteristics well. These research findings can provide an important reference on the creep characteristics of landslides, potentially aiding geotechnical engineering applications.

The residual soil on a slope can slowly move downward under the influence of gravity, forming a creep landslide. These types of landslides are known for their extensive coverage, significant magnitude, and prolonged duration of hazard. A systematic study of the creep properties of creep landslide geotechnical bodies is essential for the analysis of the deformation process and long-term safety evaluation of landslides. This paper focuses on studying a creep landslide involving residual soil in western Henan Province. The creep characteristics of residual soil with different stone content are investigated through direct shear creep experiments. The findings reveal that stone content has a profound impact on the creep behavior of residual soil. As the stone content of the soil increased, the structure of the test soil changed significantly, resulting in a gradual decrease in its shear creep. The Burgers model can effectively fit the deceleration creep and steady-state creep stages of the residual soil. With the increase in stone content, the four parameters of the Burgers model show a significant increase, with the instantaneous elasticity coefficient G1 and the viscosity coefficient eta 1 experiencing more noticeable changes. The average long-term strength of specimens with different stone content is only 54% of their instantaneous strength. Additionally, as the stone content increases, the ratio of long-term strength to instantaneous strength also increases. Notably, the long-term strength of specimens with 10-30% stone content is significantly lower than that of specimens with 50-70% stone content.