PSI - Issue 62

Vincenzo Simeone et al. / Procedia Structural Integrity 62 (2024) 561–568 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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raw information about the hypothesized movement of the landslide, but with both it is possible to calculate horizontal and vertical velocity, Vel E and Vel U : { = cos + sin = cos + sin (1) Where  A and  D are the incidence angle in the order for the ascending and descending trajectories and V A and V D are in the order the velocities of the displacements evaluated for the ascending and descending trajectories. In the end, it is possible, through a critical analysis of all the available evidence, to claim to recognize the phenomenon and its causes. 3. Case studies The main area of interest in this paper is South Italy, where the lifting of the Appenine chain in geologically recent era causes continuous transformations of the territory. The interaction between the terrain and infrastructures in these conditions leads deformations which, cumulated over the decades, could cause the collapse of the bridges, being hazardous for human lives. In this section, some cases are presented, where slow gravitative landslides deform the arches in a particular way, called “nutcracker” . In Basilicata, near the Ionian sea coast, it is considered a bridges on the SP5, formerly SP 103, between Craco (MT) and Pisticci (MT), partially collapsed in 2013; the bridge on SP 15, formerly SP 154, connecting Bernalda (MT) to Ginosa (TA), shows cracks that predict a future collapse of the first arch and in Calabria it is analyzed a former railway bridge, the 12-arch bridge of the dismissed Paola-Cosenza railway. 3.1 Mansory arch bridges on SP5 between Craco (MT) and Pisticci (MT) On the road between Craco and Pisticci two bridges are considered, which manifested similar deformation conditions. One of them partially collapsed on February 23rd 2013 (Fig. 1). The bridge is located in the Bradanic Trough, a large area where Sub-Appenine clays outcrop, alternating with middle-upper Pleistocene and Quaternary clays and sands, deformed by the uplift due to the tectonic thrust of the Appenine chain (Doglioni et al., 2019). On the top of the hills, regressive terraced marine deposits outcrop, while alluvial deposits characterize the bottom of valleys. The area is characterized by a dense secondary hydrographic network with deep narrow valleys, with steep or sub vertical flanks. On the base of the geomorphological evaluations of the authors, they cannot be due to the erosion phenomena, but mainly to the fracture induced by the tectonic uplift. So, their flanks are affected by a sort of really slow toppling deformations, and by landslides due to their recent origin. In this case, valleys are oriented from N-W to S-E, and it is assumed that a slow gravitative landslide involves the N-W flank (Figure 1.C), where a block collapsed on the bottom of the valley. The bridge was built in masonry, 25 m long and 6 m large, parallel to a former railway bridge. The side of the bridge presents an ogival deformation, more marked near the landslide and with cracks on that part of the abutment, while the south side was the collapsed one (Figure 1.A). Interferometric analysis based on Copernicus project EGMS targets permits to identify an area near the collapsed part of the bridge, on the arch, with opposite velocity, consistent with an uplift movement of the arch (Figure 1.B). From the EGMS platform it is possible analyze PS only in descending geometry, probably due to its orientation; considering the N-E abutment, the MPs show a movement away from the satellite, so it is supposed that the landslide and the abutment could have a E-W movement or a down lift or, more likely, a combination. However, in this case PSs obtained from the SPINUA algorithm (Stable Point Interferometry even in Unurbanized Areas) (Bovenga et al., 2004) are available, developed by the company GAP (Geophysical Applications Processing - http://www.gapsrl.eu). The acquiring periods are quite similar, both start on April 2015, but for the EGMS it ends on 31/12/2022, and for SPINUA on 04/08/2023. Although more PSs were detected, the points on the abutment confirm the EGMS measurement, and it is find out an area near the collapsed one, on the arch, with opposite velocity, consistent with an uplift motion of the arch (Figure 1.B).