NEW STRATEGIES FOR RISK ASSESSMENT OF RIVER EMBANKMENTS IN ALLUVIAL PLAN IN MOUNTAIN AREA: application to the right Adige levee in Salorno-Egna stretch

Improving knowledge of existing levees through on site investigation and monitoring is an important step in evaluating their safety and that of the surrounding area. Nevertheless, these activities are complex due to the considerable levee length and the high spatial variability of soils composing the levee body and foundation, especially in mountain areas and in presence of paleochannels in the subsoil. In order to investigate the reliability of new advanced techniques proposed for characterizing the soil stratigraphy and the seepage condition within the levee foundation, two new equal test-sites were realized along the Adige River levee in Bolzano Province (Italy). In each of them, five boreholes, drilled in a 20 m-side square area straddling the embankment, provided the opportunity to test a relatively new technique for obtaining undisturbed samples and a prototype permeameter, both suita-ble for granular soils. In addition, each well hosts four different types of monitoring equipment, among which also Distributed Fiber Optical Sensors (DFOS) cables, here used to detect the vertical temperature variations along the well. The present thesis focuses on the geotechnical characterization of the two test-sites and the critical analysis of the data acquired from the different implemented monitoring systems during the significant flooding event happened on 5 August 2021 and during some “water injection” tests. All the datasets collected in the field are analyzed to better understand the hydraulic behavior and the safety conditions of the levee, and to fully assess the reliability and potential of the new techniques tested in field applications. To conclude, a comparison of deterministic and probabilistic methods for evaluating the safety of river levees is conducted, considering the variability of the geotechnical input parameters characterizing the sections under investigation.