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A hysteretic hydraulic constitutive model for unsaturated soils and application to capillary barrier systems

Scarfone, Riccardo; Wheeler, Simon J.; Lloret-Cabot, Marti

A hysteretic hydraulic constitutive model for unsaturated soils and application to capillary barrier systems Thumbnail


Authors

Riccardo Scarfone

Simon J. Wheeler



Abstract

Unsaturated soils exhibit water retention hysteresis, with different water retention behaviour during drying and wetting paths. Water retention hysteresis has often been modelled using expressions for the main drying and main wetting water retention curves that are unsatisfactory at low values of degree of saturation. In addition, the effect of retention hysteresis on the unsaturated hydraulic conductivity behaviour has typically not been explicitly considered. This paper presents a new hysteretic hydraulic constitutive model for the water retention and hydraulic conductivity behaviour of unsaturated soils, which is effective and easy to apply. The model includes: (i) main wetting and main drying water retention curves modelled with a modified version of the van Genuchten model, improved at low degree of saturation; (ii) hysteretic scanning water retention curves modelled using a bounding surface approach; (iii) the effect of hydraulic hysteresis on a soil hydraulic conductivity curve (SHCC) model improved at low degree of saturation and including the effect of liquid film conductivity. The new hysteretic hydraulic model is then validated against experimental data. After implementation in the finite element software Code_Bright, the new hydraulic constitutive model is applied in a numerical study of the impact of hydraulic hysteresis on the behaviour of capillary barrier systems (CBSs). Water retention hysteresis, which has typically been neglected in the modelling of the hydraulic behaviour of CBSs, is shown to have a significant impact on: (i) movement and redistribution of water within the finer layer of a CBS; (ii) the phenomenon of water breakthrough across the interface between the finer and coarser layers of a CBS and the subsequent restoration of the CBS after infiltration at the ground surface ceases; (iii) the prediction of evaporation from a CBS into the atmosphere.

Citation

Scarfone, R., Wheeler, S. J., & Lloret-Cabot, M. (2022). A hysteretic hydraulic constitutive model for unsaturated soils and application to capillary barrier systems. Geomechanics for Energy and the Environment, 30, Article 100224. https://doi.org/10.1016/j.gete.2020.100224

Journal Article Type Article
Acceptance Date Oct 4, 2020
Online Publication Date Oct 6, 2020
Publication Date 2022-06
Deposit Date Nov 24, 2020
Publicly Available Date Nov 24, 2020
Journal Geomechanics for Energy and the Environment
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 30
Article Number 100224
DOI https://doi.org/10.1016/j.gete.2020.100224

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