Abstract
In the context of rainfall-induced landslides involving pyroclastic soils, the present work analyzes the influence of cover thickness on slope stability conditions. To this aim, the slope failure that occurred in Nocera Inferiore (4th March 2005) is selected as a reference test case, providing the actual weather forcing history that preceded the event, the hydraulic characterization of the soil involved, and the lowermost boundary condition (variously fractured calcareous bedrock underlying the cover). By maintaining unchanged soil hydraulic properties, the relationship between domain thickness, initial soil suction distribution, and slope instability induced by critical rainfall is investigated by numerical analyses. These refer to a rigid unsaturated domain subject to one dimensional flow conditions under the effects of incoming (precipitation) and outcoming (evaporation) fluxes applied at the uppermost boundary. The main outcomes indicate that critical event duration increases significantly with increasing the domain thickness. This relationship is strongly influenced by initial suction distribution. A linear relationship results for soil suction that is assumed to be constant at the beginning of the critical event. However, this relationship is quadratic if, by simulating the actual antecedent meteorological conditions, suction at the beginning of the critical event is the main function of the domain thickness. Additional numerical analyses were carried out to characterize the influence of a different lowermost boundary condition. Outcomes indicate that, for the same thickness, critical duration is substantially longer if the cover contact is with the same material as that of the cover.
Highlights
In recent decades, rainfall-induced landslides have caused increasing damage and causalities globally [1]
Analyses: critical duration against domain thickness computed for four different initial suction values
In order to better investigate the effects of antecedent rainfall, several weretocarried out using the setting adopted in B analyses but backdating the starting time of the analyses critical events
Summary
Rainfall-induced landslides have caused increasing damage and causalities globally [1]. As communities and decision makers have increased their interest in environmentally compliant solutions, an increasing number of investigations have been focused on improving the efficiency of nature-based approaches [2] and non-structural approaches (early warning systems) [3,4,5]. Among these phenomena, debris avalanches and debris flows occurring in silty volcanic cover [6,7,8]. Have been greatly considered, as they have increased in frequency and magnitude globally during the past three decades. A typical susceptible stratigraphy comprises cover of a few meters placed over flysch deposit, Geosciences 2020, 10, 228; doi:10.3390/geosciences10060228 www.mdpi.com/journal/geosciences
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