E3S Web Conf.
Volume 9, 20163rd European Conference on Unsaturated Soils – “E-UNSAT 2016”
|Number of page(s)||6|
|Published online||12 September 2016|
On the mechanisms and kinetics of evaporation of a compacted silt
1 Université libre de Bruxelles (ULB), BATir Department, Laboratory of GeoMechanics, Brussels, Belgium
2 Université libre de Bruxelles (ULB), TIPs Department, Brussels, Belgium
In order to define a convective evaporation model able to reproduce the evaporation rates according to the atmospheric conditions, drying tests have been performed on cylindrical samples of a compacted silt in a closed chamber where the relative humidity of the air is controlled by means of saturated saline solutions. Calibrating such models using experimental results from small sample sizes can indeed be an interesting alternative to simplify the experimental procedures and to reduce the test duration in comparison with the standard in-situ tests (e.g. lysimeter). However the influence of the size of the samples on the kinetics of evaporation has to be investigated. Samples with different diameters and heights are therefore tested. The results show that the observed mechanisms of drying are similar to those at the scale of the geostructure if the dimensions of the sample are higher than a critical height and a critical diameter. We show then that the experimental critical height is consistent with the concept of critical length proposed by Lehman et al. (2008), who expresses analytically when the hydraulic connection between the sample surface and the drying front is upset. Finally the kinetics of evaporation recorded under different relative humidities highlight that the mass transfer coefficient defined in the convective evaporation model does not depend on the relative humidity.
© The Authors, published by EDP Sciences, 2016
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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