Risk assessment of the Groppo Sovrano rock wall: interaction between rockfall dynamics and a Provincial Road through 3D analysis

Located in the Emilia-Romagna region (Italy), the Groppo Sovrano rock wall is part of a series of sandstone scarps originated as a result of landslide phenomena and deep gravitative slope deformations (DGSD). The importance of this specific area derives from the presence of the Provincial Road SP75, connecting the municipalities of Corniglio and Monchio delle Corti, and located just below the main scarp. Over the years, SP75 has been affected by several rockfall events hindering its usability and leading to road closures. For this reason, it was decided to carry out an extensive study of the area in order to determine the rock wall conditions, describe the phenomenon evolution, and identify effective mitigation measures. Firstly, a comprehensive aerial survey taking advantage of optical and laser-based sensors allowed to create a 3D model of the entire Groppo Sovrano face, which was then exploited for the identification of discontinuity systems in the rock mass. Moreover, the model was used to perform a 3D rockfall analysis aimed at modelling the phenomenon and defining the most relevant rock trajectories. These results were fundamental to plan the realization of appropriate measures, such as the installation of rockfall barriers, for risk mitigation purposes.