Laboratory Tests to Simulate the Rainfall Infiltration Process of Pyroclastic Soils Subject to Instability

Each year, rainfall events trigger a large number of landslides causing damage and victims. The study and forecast of rainfall-induced landslides is a field of great importance. Many research activities aim to understand landslide processes and to improve early warning systems. Infiltration processes and underground water circulation have an important role to define failure processes characteristics. In this work, some results from tests performed with a physical slope model are reported. Some experimental tests were conduced, using pyroclastic soil from Sarno area (Southern Italy—near the volcano Vesuvio), affected by landslide events on 5 May 1998. In these places the stratigraphy are composed from limestones covered by layers of pyroclastic deposits. These soils are the product of different eruptions of more volcanoes like Somma-Vesuvius, Flegrei fields and other volcanoes present in the Region no longer active. Generally, they are incoherent deposits with variable granulometry that range from sands, silty sands and silts (ashes) until sands with gravel (pumice) and gravels. Some tests considering both homogeneous and stratified deposits of ash and pumice were carried out. During the tests, both during evaporation and infiltration processes, suction and volumetric water content at different depth were measured by using the appropriate sensors. By comparing and analysing all the collected data it was possible to study the infiltration processes that lead to the failure and the difference between the stratified and the homogeneous deposit.