PSI - Issue 84

Alice Vitaletti et al. / Procedia Structural Integrity 84 (2026) 191–198

192

Keywords: landslides; highway bridges; InSAR; FEM simulation; infrastructure monitoring.

1. Introduction Landslides, alongside earthquakes and floods, represent a widespread hazard and can pose a significant threat to critical infrastructure. In Italy, susceptibility to slope instability is particularly high due to its complex geological and geomorphological setting, which results in numerous active or potentially unstable slopes (Peruccacci et al. 2023). Landslides are typically triggered by a combination of human-induced modifications to the environment and natural factors (e.g., precipitation, snowmelt, or seismic activity), which may be further exacerbated by climate change (Guo & Cui 2020; Ponziani et al. 2013; Salciarini et al. 2016, 2019). The interaction between landslides and infrastructure can result in structural deformation, service disruption, or, in the most severe cases, partial collapse. Recent studies have reported an increase in bridge collapses or structural damage associated with landslides, highlighting the need for reliable tools to support risk investigation and management (Gabrieli et al. 2024; Salciarini et al. 2024a). Field monitoring techniques, although essential for characterising slope geometry and displacement mechanisms, are often constrained by high installation and maintenance costs and limited spatial coverage (Aceto et al. 2021). As a complement to in situ measurements, Interferometric Synthetic Aperture Radar (InSAR) has become widely used to detect ground deformation over large areas with frequent revisit times (Casagli et al. 2016). Multi-interferogram approaches, such as PS-InSAR, allow the monitoring of slow-moving landslides and the detection of anomalous displacement patterns (Bianchini et al. 2013; Calvello et al. 2016). However, InSAR measurements can capture only the deformation component along the satellite line of sight (LOS) and do not provide information on the mechanical response of the slope or interacting structures. Numerical modelling, such as Finite Element Method (FEM), offers a complementary perspective by simulating the physical processes governing slope deformation and the response of structural elements under varying loading conditions (e.g., Castaldo et al. 2014; Cernuto et al. 2026; Salciarini et al. 2024b). Yet, the accuracy of numerical analyses relies on the availability of geotechnical parameters, which may be challenging to obtain in data-scarce contexts. Given the respective strengths and limitations of the two methods, combining InSAR observations with FEM modelling represents a promising strategy for improving the interpretation of bridge-landslide interaction, especially where ground-based data are limited. Previous research has shown that combined InSAR-FEM methods can enhance the characterisation of landslides in open-pit mines and urbanised slopes (e.g., Ma et al. 2021; Sun et al. 2023), while applications involving bridges remain comparatively recent, with encouraging results reported in a few studies (e.g., Cernuto et al. 2025; Farneti et al. 2023). This study applies such a combined approach to the analysis of a slow-moving landslide partially interacting with a highway bridge, inspired by a real case along an Italian highway. A more extensive description of the methodology is provided in Vitaletti et al. (2026). The aim is to evaluate the potential of using satellite-derived displacement and numerical simulation to support infrastructure managers in understanding landslide evolution and identifying areas prone to instability that may require monitoring or mitigation. 2. Study area The proposed approach was applied to a real scenario of bridge-landslide interaction located along the Ligurian section of the A12 highway in northern Italy, between Sestri Levante (GE) and Ceparana (SP). The selected case (Fig. 1) corresponds to a landslide covering an area of about 12,122 m 2 , as mapped in the Inventory of Landslide Phenomena in Italy (IFFI), which partially affects a bridge on a moderately steep slope. This scenario was chosen as it is considered representative of a typical condition frequently encountered along highway networks in landslide-prone regions. The Ligurian highway section is characterised by a widespread distribution of slope instabilities, as documented in IFFI, making it a suitable study region for assessing the effectiveness of satellite-based monitoring strategies in supporting management of extensive highway networks exposed to recurrent landslides, where in-situ data may be limited or unavailable. In this context, freely accessible interferometric satellite products were explored to evaluate both their potential and intrinsic limitations for large-scale applications. Satellite-derived deformation data were retrieved from the European Ground Motion Service (EGMS), within the Copernicus Land Monitoring framework. EGMS provides open-access PS-InSAR products derived from Sentinel-1