PSI - Issue 84

Marco Barla et al. / Procedia Structural Integrity 84 (2026) 441–448

442

1. Introduction In the context of Italy's complex geomorphological setting, landslides frequently pose a significant threat to motorway infrastructure. To mitigate this risk, either structural interventions, such as reinforcement, or non-structural measures, including monitoring and early warning systems (EWSs), can be adopted. Numerous documented case studies show that landslides posing threats to structures or infrastructures have required either the design of extensive mitigation measures (Sakoumpenta et al, 2013; Salciarini et al., 2024; Barla et al., 2025) or management through early warning systems (Catelan et al., 2025; Barla et al., 2026). In both cases, such critical situations are best addressed by integrating construction activities with detailed monitoring and advanced numerical modeling, enabling verification of stability conditions throughout all transitional construction phases and the entire lifespan. This paper presents a case study from Northern Italy, where a landslide interacted with existing stabilization works protecting a motorway platform, necessitating a complex design for the final slope stabilization. Through detailed monitoring and advanced numerical modelling, several provisional phases were implemented to allow intervention without disrupting motorway traffic or compromising worker safety. The study outlines the monitoring strategies and modelling outcomes, highlighting how these integrated efforts enabled the safe and timely execution of stabilization works. 2. Description of the case study The slope overlooking the southbound carriageway of the A6 Torino–Savona motorway, between km 86+230 and km 86+730, is affected by a long-term landslide phenomenon. Over time, this instability has caused progressive displacement and damage to the retaining structures installed during the original motorway construction. The retaining system composed of these structures is known as “Trincea Valera” (see Fig. 1) and consists of a multi-level stabilization scheme combining piled walls, anchored reinforced concrete slabs, and auxiliary drainage and erosion control works.

Fig. 1. The Trincea Valera retaining system. The ochre-colored polygon indicates the area of the slope affected by larger movements.