From the 9-16 November 2018, M. Jaboyedoff visited at LERN University of Laval Prof Locat, Dr A. Blais-Stevens, Dr C. Cloutier and Dr D. Turmel to focus on our project of book in French about Landslides which will contain approximately 30 authors and have 33 chapters. Two third of the chapter are now written in their first version.
Chunwei Sun will stay for 2 years in the Risk Group at UNIL. Chunwei is a joint-PhD student of the Department of Geological Engineering of Southwest Jiaotong University in Chengdu, China. His research involves geochemical weathering in rock mass deterioration and the oxidation-acid erosion mechanism of black shale especially. During his stay at UNIL, he will focus on the analysis of fissure water, ion exchange and elements migration processes under water-rock chemical interaction.
Prof. Jaboyedoff as a Vice-dean visited several times University LAVAL in Québec in order to setup an international associated laboratory (Laboratoire International Associé (LIA)) between the Universities of LAVAL, INRS, Neuchâtel and Lausanne: Laboratoire international des systèmes hydrogéologiques complexes (LISHyC).
- 20-21 June 2016
- 7-16 October 2016
- 9-1.10 2017
- 4-8 March 2017
- 13-15 October 2019 QC livre LIA
Jaboyedoff participated to IDRiM 2019. The objective was mainly to be informed about the trend in risk management, unfortunately, we missed the deadline for submission, but M. Jaboyedoff act as reviewer for papers.
Emmanuel Nduwayezu and François Noël from the group participated to the Journée des Aléas Gravitaires (JAG) in Nice – Sophia-Antipolis on October 8 to 10 2019. It was a great opportunity to exchange about many topics related to natural hazards and rockfalls. Early results from the ongoing analysis of the data from the rockfall experiment performed near Barcelonnette in 2018 were presented:
Application préliminaire du comportement d’impact observé sur de réelles de chutes de pierres à la simulation 3D sur modèles de terrain très détaillés
François Noël, Emmanuel Wyser, Michel Jaboyedoff, Clément Hibert, Miloud Talib, Jean-Philippe Malet, Renaud Toussaint, Mathilde Desrues, Franck Bourrier, David Toe, Ombeline Brenguier, Teresa Gracchi, Marc-Henri Derron, Catherine cloutier, Jacques Locat
Tiggi Choanji has started a PhD project in the group RISK of the Institute of Earth Science (ISTE), University of Lausanne, under the supervision of Prof. Michel Jaboyedoff. Tiggi holds a master degree in geology from Bandung Institute of Technology (ITB), Indonesia, about the characterization and modelling of sandstone on Central Sumatera.
In Lausanne, Tiggi will work on “The Landslide Identification and Assessment in Areas with Active Movement Plates, Using Satellite Images, Infiltration Analysis and Microstructures Data”.
Welcome to Tiggi
It was a great pleasure to spent days of the field with Profs M. Chigira S. Kojima in Septmber 2019. They are now studying the deep-seated gravitational deformation in the Val Bedretto in Ticino. Huge slope deformations are visible in that region. This is the opportunity to compare to other type for such slope movements. The collaboration will continue the next years.
We have been very lucky and honoured to host the 15th LARAM school 1st @ UNIL, from 2 to 13 September 2019 on the request of the team of the University of Salerno. We organized this summer school with our PhD students, which brought together around thirty PhD students and post-docs from all over the world. Nearly 30 teachers among the best experts on the landslide risks have taught during these 15 days. It was a great success. 4 PhD of UNIL participated.
On 11 August 2019, a debris flows stroke the village of Chamoson, in Wallis (Switzerland). One car with two passengers was washed away and disappeared in the debris flows.
On August 30, some members of the group risk went in Chamoson (1) to understand the processes going on in the source area up in the valley and (2) to map with a UAV-LiDAR the deposit zone. Our colleague of geophysics, Ludovic Baron, had been spending several days searching the disappeared car with a magnetometer. However the method proved to be very efficient, the car and its passengers were not found in the inspected area.
The national Swiss television was present and produced a short report of these techniques for the evening news:
The Material Point Method (MPM), which is an extension of the particle-in-cell method , provides a promising numerical framework which can naturally handle classical problems involving severe deformations, such as landslides. Interested readers may refer to a general introduction by Fern et al. about MPM here. We are currently developing an MPM matlab solver capable of solving a variety of elastoplastic problems, ranging from granular impacts to granular collapse.
We here only intend to show some preliminary results of a typical slumping process governed by a Coulomb type material with a non-associated flow rule, considering i) a weak layer with a lower internal frictional angle, (ii) an heterogeneous cohesion field and, iii) a strain weakening behavior of the material.
The initial geometry of the problem is described in the Figure below. We can set different value for the basal friction, i.e., mu is ranging from 0 (free slip boundary) to 0.5 (increasing stick-slip behavior at the interface). The mass instantly deforms under self-weight loading, i.e., the solver does not iterate to converge toward a force equilibrium before plastic loading to occur.
The two following numerical solution after 6 seconds shows naturally an important contribution of the basal friction both on the strain localization and the runout distance of the slumping mass. This also suggest different modes of deformation regarding the frictional behavior at the basal interface.
Deeper investigations are now required to fully understand the complex nonlinear behavior of a slumping mass.