Slope Stability Assessment of the Test Site in Pagani (Campania, Southern Italy)

Flowslides are rainfall-induced events initiating with the shear failure at a depth of few meters or less, which downslope increase in volume for avalanche effect and velocity. Unfortunately, Campania Region (Southern Italy) has been historically affected by such events. They represent a relevant hazard for the structures and the infrastructures located at foothills. Predisposing conditions for flowslide initiation are related to the current values of soil water content and matric suction into the subsoil. These parameters, if correctly monitored, can represent a valuable tool for the definition of early warning strategies against these phenomena. This paper reports preliminary results on the test site set up in Pagani (SA). Its position is strategical, as it is upslope of the highway connecting Naples to Salerno in an area affected by historical events respectively occurred in 1960, 1972 and 1997; the latter reached the highway and killed two people. Topographic survey of the area has been performed with a UAV, while stratigraphic and geotechnical characterization in both field and laboratory were carried out. Here the stratigraphic setting of the site and the preliminary geotechnical soil properties are reported. Finally, soil stability has been assessed through the infinite slope model; here, the variation in the safety factor (SF) as a function of the slope angle and of different suction scenarios is shown. These results permit to identify the most critical conditions and the most dangerous areas, where flowslide triggering could occur and, thus, affect the highway downslope.