A SLIP-based post-failure model to predict the propagation of soil slips and their interaction with infrastructures

Rainfall-induced shallow landslides (also called soil slips) are natural phenomena which can be triggered suddenly anywhere, even in areas with no previous landslide history, causing unexpected damage when interacting with the built environment. The damage could be sometimes extensive, as occurred to the "Madonna del Monte"overpass located in the Italian highway A6 (Torino-Savona), which collapsed in November 2019 because of the interference of a large soil slip. This paper shows a new methodology to analyze the propagation of soil slips and their interference with infrastructures, with specific attention to roads. Failure is detected through the physically-based model SLIP, while the post-failure evolution is investigated through a simplified model, based on SLIP results and the geomorphology of the area. The proposed approach is applied to an area in Enna (Sicily, southern Italy) where on 2nd February 2014 shallow landslides were triggered after intensive rainfall, interfering with the Provincial Road SP2 and the State Road SS117bis. Volume and average speed of the debris flow are estimated by the model and could be used in further analyses of impact with the surrounding infrastructures, showing the potential of the methodology.