Modeling Root Water Uptake, Climate and Unsaturated Vegetated Clays Interactions in the Context of Shallow Foundation Soils

Abstract

Understanding the interactions between environmental solicitations and unsaturated soils are of paramount importance in Environmental Geotechnics and hydrogeology. This paper investigates the effect of these stresses on the hydraulic and thermal behavior of unsaturated clays by numerical modeling in the context of shallow footings of residential buildings. For this purpose, a Soil-Vegetation-Atmosphere interaction analysis approach was presented and was applied to an instrumented site. The meteorological data of the site were used to calculate the natural time variable boundary conditions by partitioning the evapotranspiration rate into plant transpiration and soil evaporation. A root water uptake model was used along with the atmospheric boundary condition to model the tree root effect on the soil suction, water content and temperature. Using the Hydrus 2D software, a hydro-thermal simulation was established and the results were compared to the measurements carried out both close to the foundation soil and the tree which showed good agreement with the simulation. Based on the simulation results, a test point right under the foundation was analyzed to quantify the effect of the root water uptake at that point. Simulation results showed that the water uptake by tree roots does not influence the soil right under the foundation of the building.