PSI - Issue 62

5

Diana Salciarini et al. / Procedia Structural Integrity 62 (2024) 514–521 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 6. a) Panoramic overview of the model with input seismic at the base; b) seismic time history of the selected accelerogram.

4. Results The analysis of the considered model was initially conducted without the presence of the viaduct and under static conditions. Under such circumstances, the modelled landslide exhibits very limited displacements, recording maximum horizontal shifts of 2 mm concentrated mainly in the downstream area of the landslide volume (Fig. 7a). In this case, the state of activity of the modelled landslide can be defined as "quiescent" state, meaning that this can be activated only under specific loading conditions, such as during a seismic event. The analysis of the model response under seismic conditions, by applying a seismic input at the bedrock, yields residual displacements predictions of the order of tens of centimetres at the end of the seismic event (Fig. 7b).

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Fig. 7. Results of the FE analysis: a) static conditions; b) dynamic condition.

Subsequently, the model is implemented through the construction of the viaduct with its axis positioned along the direction of the landslide. As shown in Fig. 8a, it is observed that under static conditions, deep foundations significantly contribute to stabilizing the landslide, leading to a reduction in horizontal displacements (0.06 mm). It is noteworthy how the stabilizing effect of the foundation structures concentrates the major displacements upstream of the landslide. Consistently, under dynamic conditions (Fig. 8b), a more pronounced reduction in horizontal displacements is recorded in the proximity of the foundation structures within the landslide volume.

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Fig. 8. Results of the FE analysis with the infrastructure: a) Static conditions; b) dynamic conditions.

From a quantitative perspective, the analysis of the results was conducted by inserting control points at strategically chosen positions within the landslide volume. Specifically, control points were placed at the top and base of the piers 1 and 4, as indicated in Fig. 9, where pier 1 is located within the landslide volume. The analysis focuses on evaluating the behaviour in the area at the base of the pier, corresponding to the upper part of the foundation structure, and at the top of the pier, in proximity of the deck.