PSI - Issue 62

G. Scarpelli et al. / Procedia Structural Integrity 62 (2024) 530–537 G.Scarpelli et al. / Structural Integrity Procedia 00 (2019) 000 – 000

534

5

(Figure 4) were assigned to this research unit of Università Politecnica delle Marche for landslide risk assessment. The work was organized with desk studies on the existing design and execution documentation of each bridge and with on-site visual inspections by a team comprising geotechnical engineers and geologists with the aim to evaluate the Class of Attention for landslide risk (Level 2). This work is still ongoing, but a clear picture of the possible landslide-bridge interference for the considered sample set is already emerging. Within the logic of the multilevel approach, the Class of Attention for landslide risk is only one component of the overall Class of Attention to be assigned to a bridge, which will indicate the safety management actions. The combination of the Class of Attention assigned for each of the four specific risks may result in an overall Class of Attention that does not necessarily imply the need for in-depth analyses of Levels 3 and 4. Level 4 is the only one that directly calls for a full safety verification of the infrastructure, including monitoring of the superstructure and of its components, foundations, and abutments, as well as any possible interference with unstable slopes or with erosive currents. In Figure 4a the spatial distribution of the CdA for landslide risk resulting from Level 2 evaluation is reported, together with the schematic geological map derived from Barchi et al. (2001).

a)

b)

<

c)

<

Figure 4 a) Schematic geological map (modified from Barchi et al. 2001), with indication of the CdA for landslides; b) Morphometric map based on slope and elevation parameters; c) Case studies categorized by the geological units outcropping in the area, classes of slopes and the CdA for landslides. No bridges or viaducts were allocated in the High attention class for landslide risk, 11 were allocated in the Medium-High class, 1 in the Medium class and 18 in the Low class. It is worth noting that most bridges with Low CdA are located on alluvial deposits. For the Medium CdA a significant dataset is not available, while Medium-High CdA is frequently attributed to bridges located on consistent deposits of clastic rocks, mainly composed by alternations of sandstone and pelitic layers (ratio of sandstone to pelitic levels S/P < 1/3). In Figure 4b, the morphometric map derived from the ISO cluster unsupervised classification (performed using the software ArcGIS 10.8, ESRI) is shown. Respectively, three classes are derived by coupling the slope with the elevation parameter, derived from the Digital Elevation model (10x10 m cell size, DEM) of Tinitaly (Tarquini & Nannipieri, 2012). As a result, most of the bridges with Medium-High CdA (orange class in Figure 4a) are in areas characterized by high elevation (> 661 m a.s.l.) and