Interference of Shallow Landslides in Overconsolidated Clays on the Functionality of an Important Internal Road Infrastructure

The paper presents a case study on the impact of a shallow landslide in overconsolidated clays, which was triggered during the winter of 2004–2005 due to exceptionally high pore pressures, on the operativity and serviceability of a key road artery in Sicily. During the period from 2004 to 2021, the landslide experienced several reactivations, particularly during the winter months when increased rainfall led to rising pore water pressures. These recurrent events resulted in temporary road closures and continuous restoration efforts, causing significant inconvenience for local communities and substantial economic losses for commercial, tourism, and agricultural activities in the area. In 2018, a comprehensive study was launched to reconstruct the detailed geotechnical model of the landslide, analysing its mechanical and kinematic characteristics, pore pressure regime, the depth and geometry of the sliding surface, and the causes of the landslide. The study indicates that the primary causes of both the initial landslide and its subsequent reactivations were the poor mechanical properties of the involved soils and seasonal fluctuations in pore water pressures. To ensure long-term stabilisation, the most suitable interventions were identified as the permanent reduction of pore pressures through the installation of drainage trenches and the construction of a road embankment using gabions, which also serve as drainage structures. These measures are highly effective, relatively cost-efficient, easy to implement, and environmentally sustainable.