Etude du comportement hydromécanique et de la texture des sols en vue de leur protection

• Unité de recherche: COST
• Numéro de projet: C03.0021

Mots-clé (Français)

Unsaturated soils; constitutive modelling; hydro-mechanical coupling; hydric hysteresis; wetting collapse; finite elements

Programme de recherche (Anglais)

COST-Action C15 - Technical Infrastructure and Vegetation- Improving Relations

Description succincte (Français)

Le projet de recherche s'inscrit dans le cadre de la protection des sols vis-à-vis de leur compactage induit par le passage d'engins. Il fait appel aux techniques expérimentales et aux moyens de modélisation de la mécanique des sols. Le but est de développer un outil permettant de prévoir les impacts d'une sollicitation hydromécanique d'origine anthropique sur la qualité de la texture d'un sol et des propriétés qui en dépendent.

Partenaires et organisations internationales (Anglais)

DK, FI, FR, DE, HU, IT, NL, NO, PT, SE, CH, UK

Résumé des résultats (Abstract) (Anglais)

In an effort to improve the prediction of the behaviour of most natural soils, a new stress framework is proposed along with an advanced constitutive model for unsaturated soils. Indeed, partial saturation in water of porous space is traditionally not accounted for in soil mechanics. The stakes in terms of soil protection are numerous since the unified approach enables a superior prediction of stress and strain generation within the soil mass and addresses typical hydro-mechanical behaviours such as soil collapse under heavy rains or damaging of shallow grounds exposed to action of vegetal roots. Led in the context of C15 action, the project constitutes the doctoral work of M. Nuth. The first principal activity within the study was the setting up of an experimental program, to contribute to the laboratory quantification of the dependency of the soil water retention curve on the stress history of materials. Secondly, a deepened analysis of the unified stress framework for saturation states implied an extensive gathering of data on advanced unsaturated behaviour. A single mechanical effective stress has been evidenced to be representative and relevant for the constitutive modelling. The final product of the project is the extension of an advanced constitutive model to partially saturated states. Event though the model presents complex features, such as a double way coupling between the mechanical and the hydraulic aspects, the number of parameters is limited. This is partly linked to the use of the unified effective stress and the global elasto-plastic framework. The model has been validated on several complex stress paths, showing particularly an excellent and original comprehension of the confined unsaturated materials. Numerical back prediction also shows good correlation with experimental data along drying and wetting paths. The project opens perspectives for implementation of the constitutive model into a fully coupled hydo-mehcanical finite element code, in order to simulate the behaviour of large enginnering problems such as earthdams and landslides.

Références bases de données (Anglais)

Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. [phone] Swiss Project-Number: C03.0021