PSI - Issue 84

Lorenzo Di Taranto et al. / Procedia Structural Integrity 84 (2026) 1007–1014

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effectiveness of the drainage systems, such as the wells constructed near the infrastructure prior to the current investigation campaign (Fig. 4). Conversely, the sensors installed at greater depths (-18 m and -28 m) record an opposite trend, characterized by a systematic increase in pore water pressures. Of particular significance is the condition detected at the -28 m level, where the piezometric level averages approximately -1 m b.g.l., indicating a particularly high water table in the deep horizons. During the period between March and July 2023, the piezometric level exhibited a marked responsiveness to intense rainfall events, with a significant rise in piezometric levels across all monitored cells. This response highlights the close interdependence between surface water inputs and deep pressure variations, indicating that the basal layers are promptly affected by meteoric recharge. This deep circulation appears to be sustained by the presence of sandy horizons fed by hydraulic connection systems from the surface, such as the sinkholes identified on the slope, which act as preferential pathways for the pressurization of the levels corresponding to the main slip surfaces.

Fig. 4. piezometric level trends over time (daily average) from 04/01/2022 to 01/12/2024. Piezometric sensors at depths of -7 m (red), -12 m (light blue), -18 m (orange), and -28 m (purple) b.g.l. along vertical 2.

2.3. Correlation between Displacements and Piezometric Levels The intense rainfall recorded between March and July 2023 led to a significant increase in piezometric levels across all monitored depths, confirming the high responsiveness of the hydrogeological system to meteoric forcing. The integrated analysis of inclinometer and piezometric data highlighted both active inclinometer displacements and a clear correlation between deep piezometric levels and daily rainfall. Specifically, the temporal comparison between the cumulative displacement trends of inclinometer 2 and the piezometric levels measured at -28 m below ground level (b.g.l.) reveals a clear acceleration of kinematic processes coinciding with two relative peaks in piezometric levels recorded in July 2023 and January 2024 (Fig. 5). These findings corroborate the decisive role played by deep pore water pressures in controlling the slope's evolutionary dynamics, acting as a triggering factor for sliding accelerations and directly influencing the stress state of the infrastructure.