Study of an active landslide on A16 Highway (Italy): modeling, monitoring and triggering alarm

This paper presents the preliminary results of a study carried out on an active landslide, which insists on the A16 (E842) Highway, between Campania and Puglia region (South of Italy). The area lies at the foot of a large gravitational mass, classified as “ancient landslide deposit” where a system of landslides, with different types and activity states, are present. It is characterized by the widespread presence of clayey sequences that affect the stability of the slopes looming over the highway. The site has been instrumented with a series of automated sensors, both innovative and traditional, which monitor different physical entities. Furthermore, a photogrammetry survey was carried out with a drone in order to know precisely the geometry of the slope. Once the geotechnical and hydraulic parameters were collected, a 2D finite difference numerical model (FLAC® software) of the slope was set up and a series of back analysis were carried out comparing the model results with those obtained from the monitoring database. Through these back analyses, the choice of the geotechnical parameter was refined and validated. Different physical variables and results are shown into a unique representation, in comparison with the developed model and the geological and geotechnical information. Following the trends of data, the weekly/monthly average displacements and the possible causes (heavy rainfall, raising of the water table), it is possible to study the mechanical behavior of the landslide and establish preliminary warning thresholds, which have to be verified in future. The large number of acquisitions, provided by the automated monitoring system, permits to use a statistical approach in order to identify a good reliability and increase the confidence on the results. The obtained knowledge allows for the automation of the data processing procedure and for the control of the highway stability in near real time.