MANAGING UNCERTAINTY IN EXISTING LEVEES: INSIGHTS FROM A CASE STUDY

The safety assessment of river embankments is one of the most challenging problems for geotechnical engineers. Levees are often extensive structures, spanning several kilometers. In-situ testing can yield limited insights due to inherent methodological constraints and the typically sparse spatial distribution of tests across extensive levee systems. Consequently, even with the most comprehensiveinvestigation the obtained geotechnical model is characterized by a multitude of uncertainties, related to the mechanical and hydraulic parameters, but also to the stratigraphic geometry.This study deals with the case of the levees of Adige River in Trento, Italy, where several sand boils were observed during the most recent flooding events.A geotechnical survey,which included detailed surveys, laboratory tests, and field monitoring,was recently conducted for assessing thepotential collapses due to underseepage and designingpossible improvement interventions. Based on the results of the site investigations, finite element analyses were conducted to examine the seepage within the river embankments and evaluate their safety in terms of exit gradient. The present study underscores the pivotal role of both soil hydraulic conductivity and stratigraphic geometry on the system response in terms ofexit gradient of river embankments, emphasizing the necessity for a careful consideration of both these factors in the planning of site investigations and engineering designs.