Coupling of hydraulic and mechanical behaviour in unsaturated compacted clay

Tarantino, Alessandro; Tombolato, Sara

doi:10.1680/geot.2005.55.4.307

Cited by 178 publications

(96 citation statements)

References 20 publications

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“…(16) has been suggested through replacing the degree of saturation (S r ) by the effective degree of saturation (S e ) (Vanapalli et al 1996;Tarantino and Tombolato 2005;Alonso et al 2010;Lu et al 2010;Zhou et al 2012b). Pore water is divided into two categories: free water and residual water.…”

Section: Shear Strength Criterionmentioning

confidence: 99%

Capillary water retention curve and shear strength of unsaturated soils

2016

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This paper proposes a new water retention model for unsaturated soils, which takes into account capillary condensation of adsorbed water. In this model, the degree of saturation of a soil is separated into that based on capillary water and that based on adsorbed water. Through analysis of a partially saturated two-cylinder system, a new shear strength criterion for unsaturated soils is proposed, in which only the degree of saturation based on capillary water contributes to the variation of shear strength with suction. The proposed shear strength criterion is justified against thermodynamic principles and is compared against existing criteria in the literature, which shows that it provides a much improved prediction of the experimental data for a wide range of suction values.Key words: unsaturated soils, capillary water retention, thermodynamics, shear strength.Résumé : Dans le contexte de cette étude, on propose un nouveau modèle de rétention d'eau pour les sols non saturés qui prend en compte la condensation capillaire d'eau adsorbée. Selon le modèle de rétention d'eau proposé, le degré de saturation d'un sol comporte deux composantes séparées, soit celle en fonction de l'eau capillaire et l'autre en fonction de l'eau adsorbée. Au moyen de l'analyse d'un système à deux cylindres partiellement saturé, on propose un nouveau critère de résistance au cisaillement pour les sols non saturés, selon ce critère seulement le degré de saturation en fonction de l'eau capillaire contribue à la variation de la résistance au cisaillement avec la succion. On justifie le critère de résistance au cisaillement proposé par rapport aux principes thermodynamiques. On compare le critère de résistance proposé aux critères puisés dans la littérature, ce qui démontre qu'il offre une prédiction grandement améliorée des données expérimentales, et ce, pour une vaste gamme de valeurs de succion. [Traduit par la Rédaction] Mots-clés : sols non saturés, rétention d'eau capillaire, thermodynamique, résistance au cisaillement.

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Section: Shear Strength Criterionmentioning

confidence: 99%

Capillary water retention curve and shear strength of unsaturated soils

2016

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“…Equation (2a) for the effective degree of saturation was already introduced by Romero & Vaunat (2000) and Tarantino & Tombolato (2005). It is proposed that the unsaturated soil behaviour be defined in terms of two independent stress fields.…”

Section: Effective Degree Of Saturation and Constitutive Stressmentioning

confidence: 99%

“…On the other hand, many s(w, ª d ) relationships can be found in the literature (e.g. Li, 1995;Romero et al, 1999;Tarantino & Tombolato, 2005).…”

Section: Introductionmentioning

confidence: 99%

Compacted soil behaviour: initial state, structure and constitutive modelling

Alonso¹,

Pinyol²,

Gens³

2013

Géotechnique

181

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The paper explores the behaviour of compacted soils throughout the (dry density-water content) compaction plane by means of a conceptual framework that incorporates microstructural information. The engineering properties of compacted soils are described by an initial state in terms of a yielding stress, soil suction and a microstructural state variable. Microstructure is defined by the ratio of microvoid volume to total void volume. The pattern of variation of the microstructural parameter within the compaction plane has been determined, for some compacted soils, by analysing mercury intrusion porosimetry data. The microstructure of wet and dry compaction conditions can then be quantified. To ensure consistency, the framework is cast in the form of a constitutive model defined in terms of an effective suction and a constitutive stress that incorporate the microstructural variable. The model is shown to be consistent with a number of experimental observations and, in particular, it explains the intrinsic collapse potential of compacted soils. It predicts, for a common initial suction, a higher collapse potential for dry of optimum conditions than for wet compaction. It also predicts in a natural manner the observed evolution of soil compressibility during drained or undrained loading. Model capabilities are illustrated by application to a testing programme on statically compacted samples of low-plasticity silty clay. The compression behaviour of samples compacted wet and dry of optimum and the variation of collapse strains with confining stress have been successfully reproduced by the model.

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“…The volume of voids in a soil depends on the granulometry and on the state of compaction of the medium. In deformable soils, it has been evidenced that the soil deformation has an effect on the shape of the soil-water retention curve (SWRC) (Romero and Vaunat 2000;Miller et al 2002;Sugii et al 2002;Tarantino and Tombolato 2005;Salager et al 2007;Miller et al 2008;Parent et al 2011). Conventionally, the main source of deformation is the external, mechanical stress exerted on the soil.…”

Section: Introductionmentioning

confidence: 99%

Investigation into water retention behaviour of deformable soils

et al. 2013

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Abstract:The paper presents an experimental and modelling approach for the soil-water retention behaviour of two deformable soils. The objective is to investigate the physical mechanisms that govern the soil-water retention properties and to propose a constitutive framework for the soil-water retention curve accounting for the initial state of compaction and deformability of soils. A granular soil and a clayey soil were subjected to drying over a wide range of suctions so that the residual state of saturation could be attained. Different initial densities were tested for each material. The soil-water retention curves (SWRCs) obtained are synthesized and compared in terms of water content, void ratio, and degree of saturation, and are expressed as a function of the total suction. The studies enable assessment of the effect of the past and present soil deformation on the shape of the curves. The void ratio exerts a clear influence on the air-entry value, revealing that the breakthrough of air into the pores of the soil is more arduous in denser states. In the plane of water content versus suction, the experimental results highlight the fact that from a certain value of suction, the retention curves corresponding to different densities of the same soil are convergent. The observed features of behaviour are conceptualized into a modelling framework expressing the evolution of the degree of saturation as a function of suction. The proposed retention model makes use of the theory of elastoplasticity and can thus be generalized into a hysteretic model applicable to drying-wetting cycles. The calibration of the model requires the experimental retention data for two initial void ratios. The prediction of tests for further ranges of void ratios proves to be accurate, which supports the adequacy of formulated concepts.Key words: soil-water retention curve, unsaturated soils, deformable media, constitutive modelling. Mots-clés : courbe de rétention d'eau du sol, sols non saturés, médium déformable, modèle constitutif.

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Coupling of hydraulic and mechanical behaviour in unsaturated compacted clay

Cited by 178 publications

References 20 publications

Capillary water retention curve and shear strength of unsaturated soils

Capillary water retention curve and shear strength of unsaturated soils

Compacted soil behaviour: initial state, structure and constitutive modelling

Investigation into water retention behaviour of deformable soils

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