Instability of flood embankments due to pore-water pressure build-up at the toe: lesson learned from the Adige River case study

Abstract

A case study is presented of the Adige River embankment, a segment of which experienced instability of the landside slope due to the development of uplift pressures. Soil profile and hydromechanical properties of the embankment and foundation materials have been assessed via site investigation, laboratory testing, and field monitoring for two cross sections, within and outside the failure segment. The hydromechanical model developed thereof was first validated against its ability to reproduce the probability of failure for the two sections with a first-order, second-moment (FOSM)-based approach. Comparison of water flow regimes between the two sections was then used to highlight the importance of the hydraulic properties of the material on the landside for the development of uplift pressures at the toe of the embankment. The lesson learnt from this case study is that the hydraulic response of the ground on the landside may play a critical role on the stability of flood embankments and its characterization should therefore not be overlooked when planning site investigation.