Analysis of an excavation-induced landslide in stiff clay using the material point method

The results of an analysis concerning a landslide occurred in Calabria (Southern Italy) in 2014 are presented. This landslide was triggered by some excavations carried out at the slope toe to allow the construction of a power plant. Failure developed mainly within a thick layer of stiff clay that experienced a pronounced strain-softening behaviour during the laboratory tests. The landslide involved some gabion walls and a sheet-pile wall, which were severely damaged. The paper focuses on the triggering mechanism of the landslide and on its evolution after the slope failure (run-out process). To simulate the occurred deformation processes, the material point method (MPM) is used along with a strain-softening Mohr–Coulomb constitutive model in which the soil strength reduces with increasing deviatoric plastic strain. In this connection, an analytical and simple to use methodology is proposed to reduce the mesh influence on the numerical results. The study shows that a progressive failure occurred in the slope owing to the excavations. Location of the failure surface, displacement magnitude and final configuration of the landslide body resulting from the numerical simulation are in good agreement with the observed ones. Some kinematical aspects of the landslide are also discussed.