The Undrained Behaviour of an Air-Fall Volcanic Ash

Luciano Picarelli,Reza Darban,Salvatore Lampitiello,Lucio Olivares,Emilia Damiano

doi:10.3390/geosciences10020060

Luciano Picarelli, Reza Darban + Show 3 more

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https://doi.org/10.3390/geosciences10020060

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Journal: Geosciences	Publication Date: Feb 5, 2020
Citations: 10	License type: CC BY 4.0

Affiliation: University of Campania "Luigi Vanvitelli"

Abstract

Pyroclastic soils are widespread in the world. In particular, they cover a great part of Campania, a densely populated country of Southern Italy, where some distinct volcanic centers are present. In these soils, precipitations can trigger fast flow-like landslides causing destruction and loss of human lives. The movement style, the high velocity and the long run-out of these landslides are an indication of the occurrence, in the saturated soil mass, of mechanisms of undrained instability due to the inability of soil to sustain the deviator stress related to the slope condition. This paper reports the results of a wide experimental laboratory program carried out on a volcanic ash, which recently has been the seat of a killer landslide, stressing the factors that govern the undrained response of these materials.

Highlights

Pyroclastic soils are widespread in the world
For higher values of e (Figure 4a), there is a transition towards a brittle response due to generation of excess pore pressures: after having reached a peak, the a peak, the the deviator soil cannot sustain the deviator stress reduces which progressively reduces of until soil reached cannot sustain stress which progressively until the reaching the the steady reaching of the steady state condition which is represented by a practically unique straight line, the statereached condition which is represented by a practically unique straight line, the SSL, regardless of the a peak, the soil cannot sustain the deviator stress which progressively reduces until the SSL, regardless of the initial soil state
A wide area of Campania is mantled by unsaturated pyroclastic soils, which are stable even on steep slopes thanks to suction

Summary

Introduction

Pyroclastic soils are widespread in the world. They cover a great part of Campania, a densely populated country of Southern Italy, where some distinct volcanic centers are present. In these soils, precipitations can trigger fast flow-like landslides causing destruction and loss of human lives. This paper reports the results of a wide experimental laboratory program carried out on a volcanic ash, which recently has been the seat of a killer landslide, stressing the factors that govern the undrained response of these materials

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