Modelling heat and moisture transport in the ANDRA/SKB temperature buffer test

Hökmark, Harald; Ledesma, Alberto; Lassabatère, Thierry; Fälth, Billy; Börgesson, Lennart; Robinet, Jean-Charles; Sellali, N.; Sémété, P.

doi:10.1016/j.pce.2006.04.024

Cited by 21 publications

(21 citation statements)

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“…Nevertheless, Gens & Alonso (1992) showed that predicting the mechanical behaviour of expansive clays requires introduction of more complex mechanisms. In terms of numerical modelling, several works have been performed to model the thermo-hydro-mechanical behaviour of compacted expansive clays used as engineered barrier in geological radioactive waste disposals (Thomas & Cleall, 1999;Börgesson et al, 2001;Rutqvist et al, 2001;Sanchez et al, 2005;Alonso et al, 2005;Hökmark et al, 2007). However, the main thermomechanical behaviour such as the reduction of mean yield stress upon heating or the contraction when heating at large OCR were not taken into account in these studies.…”

Section: Introductionmentioning

confidence: 99%

Modelling the thermomechanical volume change behaviour of compacted expansive clays

Tang

Cui

2009

Géotechnique

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Compacted expansive clays are often considered as a possible buffer material in high-level deep radioactive waste disposals. After the installation of waste canisters, the engineered clay barriers are subjected to thermohydromechanical action in the form of water infiltration from the geological barrier, heat dissipation from the radioactive waste canisters, and stresses generated by clay swelling under almost confined conditions. The aim of the present work is to develop a constitutive model that is able to describe the behaviour of compacted expansive clays under these coupled thermo-hydromechanical actions. The proposed model is based on two existing models: one for the hydromechanical behaviour of compacted expansive clays and another for the thermomechanical behaviour of saturated clays. The elaborated model has been validated using thermo-hydromechanical test results on compacted MX80 bentonite. Comparison between the model prediction and the experimental data shows that this model is able to reproduce the main features of volume changes: heating at constant suction and pressure induces either expansion or contraction; the mean yield stress changes with variations of suction or temperature.

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Section: Introductionmentioning

confidence: 99%

Modelling the thermomechanical volume change behaviour of compacted expansive clays

Tang

Cui

2009

Géotechnique

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“…Using the fitted pore values to predict the hydraulic conductivity with expression (11) gives quite a good agreement between the calculated hydraulic conductivity calc and the experimental Table 7: Parameter values obtained by fitting the effective diffusion coefficient vs. size of the diffusing molecule by the power law expression (15). The numbers in the top line are taken from [23].…”

Section: The Effective Diffusion Coefficients and The Geometric Factomentioning

confidence: 67%

“…As engineered barrier, mainly bentonite is studied. A frequently used type of bentonite is MX80, which is studied as backfill material by Andra [5,15], NAGRA [4], and the Swedish Nuclear Fuel and Waste Management Co. (SKB) [16,17].…”

Section: Introductionmentioning

confidence: 99%

The Dependency of Diffusion Coefficients and Geometric Factor on the Size of the Diffusing Molecule: Observations for Different Clay-Based Materials

et al. 2017

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In order to investigate in more detail the relation between the size of diffusing molecules and their diffusion coefficients (and geometric factors), diffusion experiments with gases of different size and tritiated water (HTO) have been performed on different clayey samples (Boom Clay, Eigenbilzen Sands, Opalinus Clay, Callovo-Oxfordian Clay, and bentonite with different dry densities). We observed that, for unreactive gases in clayey materials, the effective diffusion coefficient varies with the size of the diffusing molecule and this variation can be described by an exponential or a power law function. The variation of the geometric factor can also be described by an exponential function. The observed experimental relations can be used to estimate diffusion coefficients; by measuring experimentally in clay the effective diffusion coefficient of two unreactive dissolved gases with a different size, the diffusion coefficients of other dissolved gases (with a size in between the two measured gases) can be estimated by using the fitted exponential relationship.

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“…However, at higher salt concentrations and/or acidic flow conditions, the colloid population was not significant either for batch-or for in situ experiments [9]. The heat transferred from the encapsulated spent nuclear fuel will create a temperature gradient through the bentonite barrier estimated from 90 • C at the canister-bentonite interface to 15 • C at the bentonite-rock wall interface approximately [10][11][12]. According to reference [12] the temperature at the buffer-rock interface is calculated as the sum of the initial undisturbed rock temperature (15 • C) and the excess temperature from the repository heat release.…”

Section: Introductionmentioning

confidence: 96%