ESR3 Caroline Chalak

Research project description

Micro-Macro Relations for Unsaturated Materials and Their Integration in Boundary Value Problems

Fellow:                    Caroline Chalak

Department:          Grenoble Institute of Technology, Grenoble, France

Supervisor:            Prof. Felix Darve 

The understanding of the complex behavior of unsaturated       soils has big importance in many applications in geomechanics. However, this complexity of the macro behavior of these granular materials can be caused by interactions at smaller scales, which makes the investigation of their microscopic properties at grain scale an important task. 

This project aim to develop micro-macro constitutive relations for three phases granular materials at low water content which helps to improve the understanding of their mechanical behavior in relation to their structures.

 A micromechanical model will be proposed and studied from a thermodynamic point of view. New features related to the presence of the capillary forces in the medium will be added and discrete element method will be used to perform the numerical simulations on an open source code YADE. Spherical grains will be used in simulations modeling the behavior of coarse granular materials like sand.

 This project that focuses on the mechanical aspects in the behavior of unsaturated soils is a part of a comprehensive research project “MuMoLaDe” including 5 work packages. My work is related to the work package 1 supposed to develop constitutive modeling and define the reference materials for simulations and experiments. The results of simulated triaxial tests will be compared with the results of the experiments done by Aleksendra Jakubczyk in the University of Nottingham. My work can be also compared to the work of Xiaogang Guo from the University of Natural Resources and Life Sciences, Vienna on hypoplastic modeling of unsaturated materials. Collaboration will be also settled with Kostantin Melnikov from ETHZ working on DEM studies of unsaturated soils.

Figure 1: Pendular water bridge connecting two spherical spheres of different radii.