Unsaturated soil mechanics in rainfall-induced flow landslides

Rainfall-induced flow landslides in coarse-grained soils pose significant threats to populations and structures due to their high velocities, long travel distance and the absence of definite warning signs during the pre-failure stage. The triggering phase of these phenomena is frequently related to rainfall events which significantly reduce matric suction in the shallower soil layers. In this paper the processes leading to the onset of such phenomena are illustrated and some observations on their modelling are briefly recalled. The failure stage at different scales is then modelled with reference to a case study from southern Italy which draws on high-quality experimental data sets from extensive in situ and laboratory investigation.