GNGTS 2019 - Atti del 38° Convegno Nazionale

354 GNGTS 2019 S essione 2.2 (4a) (4b) Following the study of Blake et al. (2002), a value of 5 cm was assumed for the threshold values of the slope displacements. Five classes were defined on the basis of the vulnerability index (Eq. 1) of the structure (Tab. 1) Table 1 - Seismic vulnerability classes. Vulnerability index Classes of Levels of vulnerability (V structure ) vulnerability 1 A Negligible 1 - 2 B Low (hydraulic leakage into the embankment) 2 - 3 C Moderate (internal erosion of the embankment) 3 - 4 D High (internal erosion of the foundation) 5 E Maximum (freeboard reduction and overflow) This simplified approach was used to classify about 100 small earth dams (Fig. 1a) located in the Alps area of the Italian Piedmont Region. Fig. 1b shows that 85% of earth dams have a high/maximum level of seismic vulnerability. Fig. 1 - (a) Localization of dams; (b) Seismic vulnerability classification of dams.