Numerical Modeling of Slow-Moving Landslides with an Unsaturated Visco-Hypoplastic Constitutive Model

Slow-moving landslides exhibit persistent slow displacement that is commonly controlled by groundwater fluctuations and saturated–unsaturated conditions. This study employs an advanced unsaturated visco-hypoplastic constitutive model within a finite-element framework to simulate the time-dependent deformation of slow-moving landslides. Time-dependent behavior is introduced through a viscous strain-rate term, while suction effects and stress history are captured within the hypoplastic formulation. A time-deformation analysis is performed, considering seepage and the evolution of suction. To reduce computational demand, the visco-hypoplastic model is applied to the shear zone where deformation concentrates, whereas the remaining slope is treated as elastic. Most parameters are derived from standard laboratory tests, and the remaining time-related parameters are calibrated using monitored displacement time series. The idealized slope analysis results quantify the impact of groundwater level fluctuations on displacement rates and deformation patterns, while field slope validation demonstrates that the model can reproduce observed landslide behavior. The proposed framework contributes to the prediction of landslide evolution and informs landslide mitigation and management.