The determination of model dimension for an embankment to study soil atmosphere interaction with Finite Element Method

In order to study the interaction between soil and atmosphere, Héricourt experimental embankment was instrumented with different equipments for collecting the meteorological data, runoff, soil temperature and volumetric water content, etc. The corresponding water flux and heat flux boundary conditions of the Hydro-thermal coupled model of unsaturated soil can be calculated based on the energy and mass balance. However, in Finite Element Method, a suitable model dimension of experimental embankment needs to be set in advance, which will diminish the effect of bottom and lateral boundaries. Therefore, in this paper, four different dimension models are calculated respectively and compared in two cases with different boundary conditions. For Case 1, top water flux boundary condition is set as infiltration and evaporation happening on the soil surface alternately. In Case 2, top heat flux boundary condition is assumed based on daily solar radiation value. Comparing the results of four model dimensions, temperature and volumetric water content distributions in four dimensions lead nearly consistent results. Therefore, with consideration of computational time and accuracy, dimension 2 or 3 is suggested for Hydro-thermal study of Héricourt embankment case.