Water retention behaviour of compacted bentonites: experimental observations and constitutive model

Dieudonné, Anne-Catherine; Gatabin, Claude; Talandier, Jean; Collin, Frèdèric; Charlier, Robert

doi:10.1051/e3sconf/20160911012

Cited by 5 publications

(4 citation statements)

References 18 publications

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“…Next, the parameter values of the macrostructural retention model were determined by fitting Eq. (6) to data from: (a) free swelling tests by Dieudonné et al [11], Likos and Lu [31], Likos and Wayllace [32] and Saiyouri et al [55] for MX-80 bentonite, (b) free swelling tests by Villar [52] for FEBEX bentonite, and (c) free swelling tests by Salager et al [57] and constant load test (at constant vertical loads of 0.026, 0.55 and 0.6 MPa) by Romero [51] for Boom clay. Confined tests were not considered in this stage since the experimental values of the net mean stress developed during the tests were not available, and p could not be calculated.…”

Section: Model Descriptionmentioning

confidence: 99%

“…Only recently, some authors have, however, started to analyse the effects of porosity structure on soil-water retention and have proposed suitable modelling strategies that can account for the evolution of pore size distribution (e.g. [8][9][10][11]23]). In this context, the present paper proposes a new approach to describe the influence of double porosity on soil-water retention.…”

Section: Introductionmentioning

confidence: 99%

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A water retention model accounting for void ratio changes in double porosity clays

et al. 2021

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This paper presents a constitutive model that predicts the water retention behaviour of compacted clays with evolving bimodal pore size distributions. In line with previous research, the model differentiates between the water present inside the saturated pores of the clay aggregates (the microstructure) and the water present inside the pores between clay aggregates (the macrostructure). A new formulation is then introduced to account for the effect of the macrostructural porosity changes on the retention behaviour of the soil, which results in a consistent evolution of the air-entry value of suction with volumetric deformations. Data from wetting tests on three different active clays (i.e. MX-80 bentonite, FEBEX bentonite, and Boom clay), subjected to distinct mechanical restraints, were used to formulate, calibrate, and validate the proposed model. Results from free swelling tests were also modelled by using both the proposed double porosity model and a published single porosity model, which confirmed the improvement in the predictions of degree of saturation by the present approach. The proposed retention model might be applied, for example, to the simulation of the hydromechanical behaviour of engineered bentonite barriers in underground nuclear waste repositories, where compacted active clays are subjected to changes of both suction and porosity structure under restrained volume conditions.

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Section: Model Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A water retention model accounting for void ratio changes in double porosity clays

et al. 2021

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“…The microstructure of bentonite has been the focus of many porosimetric and microscopic studies [2,9,30,31,34,45]. An illustration of the bentonite microstructure is shown in Fig.…”

Section: Double-porosity In Bentonitementioning

confidence: 99%

A dual-porosity model for the study of chemical effects on the swelling behaviour of MX-80 bentonite

Li¹,

Zheng

et al. 2019

Acta Geotech.

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Significant chemical influence on the swelling potential of MX-80 bentonite was observed during swelling tests where specimens were hydrated with highly concentrated brine. The maximum swelling pressure for specimens hydrated with brine was about 30% of the maximum swelling pressure for the same specimens hydrated with de-ionized water. The maximum swelling pressure was attained within tens of hours of brine infiltration and further decreased by half within a year. A fully coupled hydro-mechanical-chemical (HMC) dual-porosity model is proposed in this paper to interpret the swelling behaviour of MX-80 when infiltrated with brine. The dependence of hydraulic and mechanical properties on such factors as porosity, salinity and water content was investigated. A nonlinear elastic constitutive model was proposed to correlate the swelling pressure with the variation in the microporosity. The chemical effects on the mechanical behaviour were coupled at the micropore level. A number of relationships have been developed for MX-80, i.e. micropore permeability as a function of void ratio, water retention characteristics of micropores and macropores, micropore dependence on water content and the diffusion coefficients of the two types of pore structure. The proposed model was successful in reproducing both quantitatively and qualitatively the experimental results from two sets of infiltration experiments on compacted MX-80 bentonite.

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“…The water retention model developed by Dieudonne et al (2016) is adopted. The model considers adsorbed water in the microstructure and capillary water in the aggregate-porosity.…”

Section: Hydromechanical Formulation For Bentonite-based Materialsmentioning

confidence: 99%

Evaluation of the Instantaneous Profile Method for the Determination of the Relative Permeability Function

Dieudonné

Charlier

2017

Advances in Laboratory Testing and Modelling of Soils and Shales (ATMSS)

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Experimental determination of water permeability in unsaturated conditions is a critical issue. Among the existing experimental techniques, the instantaneous profile method is frequently used. When applied to bentonite-based materials, the method often shows that the water permeability-suction function significantly differs depending on the distance from the wetting face. Such behaviour has been interpreted as a consequence of structural changes in the sample which directly affect the water flow properties. In order to better understand the involved processes, a hydromechanical simulation of an infiltration test is performed. While structural changes are shown to affect the hydraulic properties, the computed water permeability-suction evolution is strongly affected by the interpretation of the raw experimental data.

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Water retention behaviour of compacted bentonites: experimental observations and constitutive model

Cited by 5 publications

References 18 publications

A water retention model accounting for void ratio changes in double porosity clays

A water retention model accounting for void ratio changes in double porosity clays

A dual-porosity model for the study of chemical effects on the swelling behaviour of MX-80 bentonite

Evaluation of the Instantaneous Profile Method for the Determination of the Relative Permeability Function

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