Effects of artificial barriers on the propagation of debris avalanches

The paper deals with the effects of artificial barriers on the dynamic features of unconfined flows such as debris avalanches in coarse-grained materials. These phenomena are often responsible for damage to structures and risk to human life. Artificial barriers could mitigate those threats by reducing the flow velocity and the runout distance as well as diverting the flow towards lateral zones constrained by the barriers. A quasi-3D SPH hydro-mechanically coupled model was used to simulate the propagation heights and velocities, the evolution of pore water pressures inside the flow and the entrainment of additional material from the ground surface during the propagation stage. The numerical simulations referred to (i) simple topography resembling typical in situ conditions and (ii) the case history of Nocera Inferiore (Southern Italy) where a destructive debris avalanche occurred in 2005. Different scenarios were analysed relative to the number, type and location of the artificial barriers. The numerical results highlight the variations in propagation pattern, velocity and deposition thickness of the flows, which may occur in presence of artificial barriers. Indications on favourable type and location of barriers are provided both for the simple topography and for the specific case study.