Debris flow damage incurred to buildings: an in situ back analysis

In an attempt to conduct a back analysis of the damage caused to a 19th century masonry structure due to the October 2009 flash flood/debris flow event in Scaletta Zanclea, a flood discharge hydrograph is reconstructed in the ungauged conditions. The hydrograph for the solid discharge is then estimated by scaling up the liquid volume to the estimated debris volume. The debris flow diffusion is simulated by solving the differential equations for a single-phase two-dimensional (2D) flow that employs triangular mesh elements, also taking into account the channelling of the flow through the buildings. The damage to the building is modelled using 2D finite shell elements and is based on the maximum hydraulic action caused by the debris flow. The boundary conditions provided by the openings, floor slabs, orthogonal wall panels and the foundations are also modelled. The reconstruction of the event and the damage to the case-study building confirm the location of the damage induced by the event.