A two-phase coupled FEM-MPM framework for large deformation analysis of slopes considering multiple influencing factors

Numerical simulation of slope instability remains a critical challenge in geotechnical engineering, particularly for large deformations and long-term seepage. The traditional finite element method (FEM) is prone to mesh distortion in large-deformation modeling, while the material point method (MPM) is less efficient for small deformations associated with long-term seepage. To overcome these limitations, this study proposes a novel two-phase coupled FEM-MPM framework, which is validated through two representative case studies. Subsequently, the dynamic response of the Baishuihe landslide under complex conditions, including reservoir water level fluctuations, rainfall, and seismic excitation, is investigated. The results indicate that reservoir water level drawdown and rainfall are the primary factors driving landslide deformation. Under multi-factor scenarios, the cumulative displacement exceeds the sum of individual factors. Furthermore, the combination of reservoir water level reduction and seismic excitation leads to deeper and more extensive deformation. These findings provide valuable insights into the assessment and mitigation of reservoir landslide disasters, with significant implications for engineering practice.