0000000000164011
AUTHOR
John Eichenberger
Hydromechanical behaviour of a volcanic ash
This paper presents experimental analysis and numerical modelling aimed at improved understanding and prediction of the hydromechanical behaviour of volcanic ash at various states of saturation. Results from a comprehensive experimental programme are presented in order to characterise the response of the material in terms of matric suction and confining stress changes. The evolution of the yield stress at different suction levels has been quantified. The volumetric response with suction variations allowed the analysis of the collapse-upon-wetting behaviour. Water retention and permeability are also addressed. Tests results are used to calibrate a constitutive model based on the effective s…
Techniques for the modelling of the process systems in slow and fast-moving landslides
This chapter reviews some of the current strategies for landslide modelling. Main physical processes in landslides are first recalled. Numerical tools are then introduced for the analysis of the behaviour of slow- and fast-moving landslides. Representative case studies are introduced through the chapter to highlight how different modelling strategies can be used depending on the physical processes that the modeller wants to take into account.
Effect of climate change on landslide behaviour
Landslides represent a major threat to human life, constructed facilities and infrastructure in most mountainous regions of the world. Considering future climate scenarios and modified precipitation patterns, the landslide activity will most probably change too. It is expected that shallow slips and debris flows will take place more frequently as a consequence of more extreme weather events. For the local scale of Switzerland for example, there is no increasing trend visible for the total rainfall amount, but an increasing tendency is observed for stormy events and their intensity, especially in fall, spring and winter. Some precipitation is expected to fall as rain instead of snow at highe…
One-Dimensional Transient Analysis of Rainfall Infiltration in Unsaturated Volcanic Ash
The paper presents a one-dimensional hydro-mechanical analysis of rainfall infiltration in a loose volcanic ash and the utilisation of a factor of safety for the implementation of an early-warning system. Three different rainy seasons with different rainfall patterns were analysed . The analysis aims to understand the influence of the antecedent rainfall on the wetting front, the pore-water pressures and the factor of safety. The analysis was carried out in the context of a Master project of the first author at the Laboratory for Soil Mechanics of EPFL.
Early warning thresholds for partially saturated slopes in volcanic ashes
Rainfall-induced landslides in steep soil slopes of volcanic origin are a major threat to human lives and infrastructure. In the context of constructing early warning systems in regions where extensive data on landslide occurrences and associated rainfall are inexistent, physically-based tools offer the possibility to establish thresholds for measurable field quantities. In this paper, a combined finite element infinite slope model is presented to study the transient hydraulic response of volcanic ash slopes to a series of rainfall events and to estimate seasonal safety factors. Furthermore, analytical considerations of partially saturated infinite slopes are made to define capillary stress…
Hydro-mechanical analysis of volcanic ash slopes during rainfall
Rainfall-induced landslides in volcanic ashes represent a major natural hazard in many regions around the world. Owing to their loose structure, volcanic ash slopes are prone to rainfall-induced landslides. The paper presents a continuum modelling approach for the analysis of wetting-induced instability phenomena at the onset of failure in loose volcanic ash slopes. A numerical simulation of a landslide-prone volcanic slope in Costa Rica is carried out with a two-dimensional hydro-mechanical finite-element slope model. A constitutive model based on the effective stress concept extended to partially saturated conditions is used to reproduce the volcanic ash hydro-mechanical behaviour. The m…