MODEL TEST STUDY OF EVAPORATION MECHANISM OF SAND UNDER CONSTANT ATMOSPHERIC CONDITION
Résumé
The evaporation mechanism of Fontainebleau sand using a large-scale model chamber is studied. First, the evaporation test on a layer of water above sand surface is performed under various atmospheric conditions, validating the performance of the chamber and the calculation method of actual evaporation rate by comparing the calculated and measured cumulative evaporations. Second,the evaporation test on sand without water layer is conducted under constant atmospheric condition. Both the evolutions of atmospheric parameters and the response of soil are recorded. The evaporation mechanism of sand and its actual evaporation rate are analyzed using the recorded data. The results show that the chamber exhibits a good performance and the calculation method of actual evaporation rate is relevant. Moreover,evaporation process affects soil temperature. Two large temperature gradients are identified at soil-air interface. The relative humidity of air decreases along with the evaporation process. The effect of evaporation process on soil volumetric water content is related to evaporation duration and soil resistance. The matric suction gradients of soil at surface zone increase during evaporation.