Benchmark of constitutive models for unsaturated soils

D'Onza, F.; Gallipoli, Domenico; Wheeler, Simon J.; Casini, Francesca; Vaunat, Jean; Khalili, Nasser; Laloui, Lyesse; Mancuso, Claudio; Maš́ın, David; Nuth, Mathieu; Pereira, Jean‐Michel; Vassallo, Roberto

doi:10.1680/geot.2011.61.4.283

Cited by 72 publications

(32 citation statements)

References 19 publications

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“…The proposed water retention model consequently needs to be coupled with a stress-strain model for unsaturated soils. An appropriate constitutive mechanical framework shall be elastoplastic and account for the suction effects on the stress-strain response (e.g., D'Onza et al 2010;Nuth et al 2010). As it is not the scope of this paper to describe a stress-strain model for unsaturated soils, it is proposed to decouple the mechanical model from the present conceptual framework.…”

Section: Modelling Framework For Retention Curvesmentioning

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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Section: Modelling Framework For Retention Curvesmentioning

confidence: 99%

Investigation into water retention behaviour of deformable soils

et al. 2013

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“…The compressibility curves are modelled using the Bishop stress ij = ij -u a ␦ ij + (u a -u w )␦ ij and suction s = u a -u w , where ij is the total stress, = (S r ), and ␦ ij is the Kronecker delta (e.g., Casini et al 2008;Nuth and Laloui 2008;Romero and Jommi 2008;D'Onza et al 2011;Zhang and Ikariya 2011).…”

Section: Model Adopted In Consolidation Phasementioning

confidence: 99%

Hydromechanical behaviour of a silty sand from a steep slope triggered by artificial rainfall: from unsaturated to saturated conditions

2013

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This paper presents an experimental investigation aimed at studying the hydromechanical behaviour of a silty sand from a steep slope in Ruedlingen in the northeast of Switzerland, where a landslide-triggering experiment was carried out. The hydromechanical behaviour of the statically compacted Ruedlingen silty sand has been studied under saturated and unsaturated conditions, beginning with different initial void ratios and water contents. The specimens were prepared in the laboratory using static compaction, to reproduce the mean dry density and mean water content expected in natural unsaturated in situ conditions, thus promoting specimen homogeneity and test repeatability. The choice of compaction parameters was supported by a detailed physical and microstructural investigation to produce laboratory specimens with a similar microstructure to that of the natural soil. The aim of the work was to characterize the mechanical behaviour of the soil at different gravimetric water contents in a triaxial stress path apparatus and to link the mechanical behaviour with the soil-water retention curve obtained under suction-controlled conditions with different void ratios. Soil specimens with three different gravimetric water contents were exposed to conventional isotropically consolidated drained and undrained stress paths for the water phase and to stress paths simulating in situ anisotropic compression followed by a decrease of mean effective stress at constant axial load. The radial deformation of the unsaturated specimens was measured with a laser device installed in a triaxial stress path cell. Results have been interpreted using a Bishop stress approach, evaluating the suction through the water retention curve. A simple equation has been proposed to model the compressibility behaviour of the soil tested, which depends on the parameter and the stress ratio . Possible unstable response along the stress path analysed has been investigated by means of second-order work and the validity of a unified framework has also been verified under unsaturated conditions. Key words: unsaturated soil, shallow landslide, water retention curve, instability, triaxial stress path tests. Résumé :Cet article présente une étude expérimentale visant à étudier le comportement hydromécanique d'un sable silteux provenant d'une pente raide à Ruedlingen dans le nord-est de la Suisse, où un essai de glissement de terrain provoqué a été réalisé. Le comportement hydromécanique du sable silteux de Ruedlingen, compacté statiquement, a été étudié en conditions saturées et non saturées, en débutant avec différents indices des vides et teneurs en eau initiaux. Les échantillons ont été préparés au laboratoire par compaction statique afin de reproduire la densité sèche moyenne et la teneur en eau moyenne réalistes dans des conditions naturelles in situ, et de favoriser l'homogénéité des échantillons et la reproductibilité des essais. Le choix des paramètres de compaction s'est fait selon une étude détaillée des paramètres physiques et microstruct...

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“…For example, the WRC (referring to the relationship between water content and suction) has been suggested for the prediction of shear strength properties of an unsaturated soil [11,[15][16][17]. In a typical WRC, the suction decreases with increasing water content as a sigmoid function, indicating that water content would affect the suction of soil, thus affecting the suction stress.…”

Section: Introductionmentioning

confidence: 99%

Coupled Effects of Moisture Content and Inherent Clay Minerals on the Cohesive Strength of Remodelled Coal

Zhang

Wan

et al. 2017

Energies

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Injecting water into a coal seam to enhance the cohesive strength of coal and thus minimize and reduce the coal wall spalling risk must be considered in underground coal mining systems. In general, coal with low cohesive strength contains clay minerals which may affect the stability of coal by interacting with water. Therefore, the coupled effects of moisture content and inherent clay minerals on the physical properties (i.e., cohesive strength and internal friction angle) of coal samples should be addressed. In this paper, direct shear tests were conducted by remodelling the Yiluo coal with various moisture contents ranging from 6.6% to 20.7%. According to Mohr-Coulomb failure criterion, cohesive strength and internal friction angle of coal were obtained. Afterwards, effects of moisture content and clay minerals (i.e., Kaolinite, Smectite and Illite) on the cohesive strength of coal were analysed using X-ray diffraction (XRD) method. The results show that cohesive strength increases when the moisture content rises from 6.6% to 17.6%, after which it decreases with increasing moisture content. This trend can be well illustrated by the relationship between typical water retention curve (WRC) and suction stress of soil. Therefore, a moisture content of 17.6% would be an optimal value to enhance the stability of the Yiluo coal seam.

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Benchmark of constitutive models for unsaturated soils

Cited by 72 publications

References 19 publications

Investigation into water retention behaviour of deformable soils

Investigation into water retention behaviour of deformable soils

Hydromechanical behaviour of a silty sand from a steep slope triggered by artificial rainfall: from unsaturated to saturated conditions

Coupled Effects of Moisture Content and Inherent Clay Minerals on the Cohesive Strength of Remodelled Coal

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