PSI - Issue 84

Erica Cernuto et al. / Procedia Structural Integrity 84 (2026) 1167–1174

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4. Results The outcomes of the numerical simulations describe the deformation pattern of the landslide and quantify its effects on the bridge, allowing the assessment of the final configuration of the soil–structure system under stationary conditions. The spatial distribution of total displacements |u| within the landslide volume is markedly non-uniform (Fig. 5a): maximum values of approximately 14 cm occur in the downstream area, while the upstream portion exhibits more limited movements of about 10 cm. Near the bridge, displacements reduce further to 4 cm, indicating a mitigating effect associated with the presence of the structure. A detailed analysis of the displacement components reveals a predominant trend in the horizontal components, with u x reaching −3 cm and u y up to 2.5 cm, whereas the vertical component is negligible, consistent with the expected kinematics of a predominantly translational landslide. Bridge elements within or near the landslide are strongly affected by its movement. The deformation mechanism (Fig. 5b) shows a downslope dragging of the portion of the bridge located within the landslide, driven by the horizontal thrust of the moving mass.

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Fig. 5. (a) Top view of total displacements |u| with red arrows showing the main movement direction in the NE plane; (b) Bridge deformation mechanism induced by the landslide (adapted from Cernuto et al. 2025).

Regarding the analysis of satellite data, the post-processing required for displacement decomposition was performed by combining ascending and descending PS datasets and resampling them onto a 25 m grid, which provided a single LOS time series for each synthetic point (Figs. 6a, b). The LOS evolution shows opposite signs in the two geometries for the synthetic points located within the landslide: positive in the ascending orbit and negative in the descending one, indicating a predominant horizontal component consistent with the analysed phenomenon. In addition, since the ascending geometry observes the area from the west and the descending geometry from the east, the opposite signs recorded in the two orbits clearly reveal a coherent horizontal displacement directed westward. Once the LOS datasets were combined, the decomposition procedure enabled the estimation of the actual displacement components in the local reference system aligned with the landslide movement.

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Fig. 6. Time evolution of displacements along the LOS in ascending and descending geometries for synthetic PS defined on a 25 m grid (adapted from Cernuto et al. 2025).