A Coupled Hydro-Mechanical Analysis for Slope Instability Processes in San Leo (RN, Italy)

The calcarenite rock slab, on which the medieval town of San Leo is situated, is severely tectonized and crossed by a number of joint sets and faults. It is affected by lateral spreading instability processes associated with rock falls and topples. The underlying clayey substratum is involved in movements, like earth flows and slides. In the present work these phenomena are analysed within the framework of unsaturated soil mechanics. A coupled hydro-mechanical model employing viscoplasticity (BBM-VP) is adopted herein to numerically simulate the landslide processes in San Leo region. The model allows simulating the hardening and softening processes in the rock material due to hydraulic loading and unloading, and the shear strength change with degree of saturation. The results are then compared with those obtained for the same problem but employing different constitutive model for explaining the viscoplastic behaviour that is independent on suction and based on Drucker-Prager plasticity. The differences of the two conceptual model approaches are analysed.