The Role of Geological Analysis in the Design of Interventions for the Safety of the Road Asset. Some Examples

Abstract

The Design Management—Geotechnical Unit of ANAS (National Public Road Company) is often involved in study and monitoring activities regarding some instability events affecting the road asset; generally, those events tend to compromise the functionality of the infrastructure. These circumstances are generally caused by geomorphological, hydrogeological or stratigraphic arrangements, and triggered by specific rainfall conditions that tends to modify the whole stability of the road body and the slope complex as a whole. In particular, as examples of ANAS experiences, two case histories are illustrated. Both situations concern reinforced embankments that, following rainy periods, have shown strong evidence of instability. In order to size the stabilization measures, necessary for the road restoration, a thorough study of the phenomenon, in both cases, was developed. It was realized by different stages of investigation and monitoring of roadway displacement. In addition to a thorough geological and geomorphological survey, useful in the identification of particular instability surface forms, specific site-investigation campaigns were prepared and completed by the installation of topographic, geotechnical and interferometric monitoring instruments. At the same time, the geometry of the instability and the evolution mechanisms of the movements were quantified, determining the relationships between the movements and the external conditions, especially the meteorological and hydraulic ones. This analysis is aimed to obtain all the information useful to define the lines of action that ensure the final safety of the road asset.