Definition and experimental determination of a soil-water retention surface

Abstract

Definition and experimental determination of a soil-water retention surface S. Salager, M.S. El Youssoufi, and C. SaixAbstract: This paper deals with the definition and determination methods of the soil-water retention surface (SWRS), which is the tool used to present the hydromechanical behaviour of soils to highlight both the effect of suction on the change in water and total volumes and the effect of deformation with respect to the water retention capability. An experimental method is introduced to determine the SWRS and applied to a clayey silty sand. The determination of this surface is based on the measurement of void ratio, suction, and water content along the main drying paths. These paths are established for five different initial states. The experimental results allow us to define the parametric equations of the main drying paths, expressing both water content and void ratio as functions of suction and initial void ratio. A model of the SWRS for clayey silty sand is established in the space (void ratio -suction -water content). This surface covers all possible states of the soil inside the investigated range for the three variables. Finally, the SWRS is used to study the relations between water content and suction at a constant void ratio and between void ratio and suction at a constant water content.Key words: water retention, hydromechanical coupling, retention behaviour.Résumé : Cet article traite de la définition et des méthodes de détermination de la surface de rétention sol-eau (« SWRS ») comme outil de représentation du comportement hydromécanique de sols permettant de mettre en évidence à la fois l'effet de la succion sur les changements de volumes (volume d'eau et volume total) et l'effet de la déformation sur la capacité de rétention d'eau des sols. Une méthode expérimentale de détermination de la SWRS du sol est présentée en détails puis appliquée pour un sable limoneux argileux. La prise en compte de la déformation conduit à une représentation surfacique à partir de la mesure de triplets (indice des vides -succion -teneur en eau) le long des chemins de séchage principaux. Ces chemins sont établis pour cinq états initiaux différents. Les résultats expérimentaux permettent d'établir les équations paramétriques des chemins de séchage principaux exprimant l'indice des vides et la teneur en eau en fonction de la succion et de l'indice des vides initial. Un modèle de surface caractéristique sol-eau est élaboré pour le sable limoneux argileux dans l'espace (indice des vides -succion -teneur en eau). Cette surface couvre tous les états possibles du sol dan les gammes étudiées des trois variables. La SWRS est finalement utilisée pour Õ tudier les relations entre la teneur en eau et la succion pour un indice des vides constant, et entre l'indice des vides et la succion pour une teneur en eau constante.

Consequences on water retention properties of double-porosity features in a compacted silt

“…[2,25,28,32]). Here the heterogeneity of the pore system induced by the compaction process is taken into account using a multimodal retention model, defined by Durner [9] as a linear superposition of subcurves of the van Genuchten type with the following equation: where k is the number of subsystems that assembled together give the global pore size distribution, w i are weighting factors for each subcurve subject to 0 \ w i \ 1 and P w i ¼ 1.…”

“…The water retention curve expressed in terms of water content or degree of saturation and suction is hysteretic, stress path dependent (void ratio) and depends on the pore network [1,10,16,18,19,21,23,25,27,28,31]. To properly describe its evolving water retention character, a multimodal retention model is proposed in the paper by considering a linear superposition of two subcurves of the van Genuchten [33] type.…”

Soil-Water Characteristic Curve of Residual Soil from a Flysch Rock Mass

“…A SWCC is one of the most important features in unsaturated soil mechanics and relates to the potential energy of a liquid phase, which is usually characterized by the suction ψ, to the variations in the water content w in the soil [21]. Depending on the material behavior of the soil as the suction varies, the soil water content is commonly designated in terms of the gravimetric water content w, volumetric water content θ, or degree of saturation S. For compressible soils that undergo a change in volume with a change in the suction, both the changes in water volume change and total volume should be measured [22].…”

Hydro-mechanical paths within unsaturated compacted soil framed through water retention surfaces

“…Since in situ compaction gives saturation degrees above 90%, the retention curves are only processed to values around 70%. It is possible to establish a retention surface between the pair of wetting and drying curves [8].…”