Creeping reservoir landslide progressive evolution process: from large-scale direct shear creep test to seepage-mechanical-deformation block model

Creeping reservoir landslides experience slow, ongoing deformation driven by cyclical hydrological conditions, posing a significant threat to hydropower infrastructure and nearby communities. Long-term high consolidation pressure leads to the formation of a dense soil matrix unique structure in slip zone soils, significantly affecting the reservoir landslides evolution. However, current studies often fail to adequately describe and incorporate the structural and creep properties of intact slip zone soils, results in a lack of precision and efficiency when simulating the progressive evolution process of creeping reservoir landslides. This study conducted a series of large-scale direct shear creep test in the intact slip zone soil from No.1 Linjiang landslide of Huangtupo landslide in Three Gorges Reservoir area (TGRA), to study the creep behavior and long-term strength. Subsequently, a seepage-mechanical-deformation (SMD) block model, offering higher computational efficiency and the ability to dynamically adapt to real-time hydrological boundary conditions, was developed to provide an ovel framework for simulating the progressive evolution of the No.1 Linjiang landslide. The experimental results indicate that that the intact slip zone soil exhibits distinct creep behavior characteristics and has obtained long-term strength. The performance of the proposed SMD block model is further validated by its close alignment with monitoring data, with root-mean-square errors (RMSE) of 2.556 mm and 1.167 mm for the rear and front monitoring points of the landslide, respectively, over one hydrological year. Furthermore, the simulation results highlight that the primary deformations occur at the front and rear of the landslide, with the middle section acting as an anti-sliding barrier. Overall, this study advances the understanding of creeping landslide evolution processes and enhances the simulation capabilities of landslide deformation, offering valuable insights for risk assessment and mitigation strategies in the TGRA.