Analysis of transient pore pressure distribution and safety factor of a slow clayey deep-seated landslide by 2D and 3D models

This paper is focused on pore pressure response to rainfall in a clayey, deep seated landslide of the Southern Italian Apennines. The displacements of the studied landslide, measured by several techniques, including fixed-in-place inclinometer probes with continuous acquisition, are very slow and show seasonal rate variations of about an order of magnitude. The relationship between such variations, pore pressure changes and rainfall history was investigated. A finite difference code was used in 2D and 3D conditions, carrying out transient analyses with the historical rainfall of the site as boundary condition. We analyzed how the pore pressure time trend and distribution along the slip surface, whose depth varies significantly in the three dimensions, can influence the safety factor. The comparison between calculated and measured pore pressure time trends reveals that the best agreement and a clearer picture of the global response of the landslide are achieved by using a daily discretization.