Analysis of Landslide Reactivation Mechanisms in Daunia Clay Slopes by Means of Limit Equilibrium and FEM Methods

The paper presents the analysis of the mechanism of reactivation of a deep landslide process which involves the western slope of Volturino in the Daunia Apennines (Southern Italy), where tectonized and fissured soils of poor mechanical properties outcrop. The reactivation, which is monitored by piezometers and inclinometers, takes place when the water table is approximately at the ground surface, i.e. during winter. Limit equilibrium back-analyses of the current landslide process, with a pore pressure distribution consistent with the field data, were performed to assess the in situ mobilised strengths and the depth of the sliding body. Drained finite element analyses were then carried out to simulate the reactivation mechanism by modelling the presence of a band of softened material within the slope along with the seasonal variation in seepage conditions. The results of the different analyses tend to confirm the higher instability of deep sliding bodies in the slope.