Numerical Insights into the Hydro-Mechanical Modelling of the Chieuti Slope: 3D Effects on Seepage and Deformation

The landslide activity affecting the Chieuti slope, located in the south-eastern Italian Apennines, represents a typical example of a deep-seated, currently active paleo-landslide within marine clay formations. Previous 2D hydro-mechanical analyses highlighted the relevant role of geological history on the processes currently governing landsliding. However, such analyses were inherently limited by the simplified geometrical representation and their inability to capture the 3D nature of seepage and stress–strain states of the slope. In this contribution, a 3D hydro-mechanical numerical model has been developed to overcome these limitations and to assess the influence of 3D geometry and seepage on the slope stability. The model incorporates a stress-initialisation procedure modelling the geological history and stratigraphic complexity of the slope, thus enabling a realistic simulation of its stress–strain and pore pressure responses. The results show that the 3D model effectively reproduces the spatial variability of pore pressure distribution, the development of soil plasticity within the slope, and the related strain localisation in the slope. Compared with the 2D analyses, this modelling captures critical features of stress-strain field, representing an important advancement in the numerical simulation of this landslide mechanism.