Numerical modelling of an in situ ventilation test in Callovo-Oxfordian claystone

Poster (2012, October)

Analyse des mécanismes de transfert de fluides lors d'essais de séchage convectif sur un limon

in Skoczykas, Frédéric; Davy, Catherine; Agostini, Franck (Eds.) et al Actes du colloque Transfert 2012 - Propriétés de transfert des géomatériaux (2012, March)

Des essais de séchage convectif ont été réalisés sur des échantillons de limon en vue de quantifier la cinétique de perte de masse. Ces essais ont été analysés sous l’hypothèse de l’existence d’une couche ... [more ▼]

Des essais de séchage convectif ont été réalisés sur des échantillons de limon en vue de quantifier la cinétique de perte de masse. Ces essais ont été analysés sous l’hypothèse de l’existence d’une couche limite en paroi de l’échantillon, dans laquelle des transferts de masse et de chaleur ont lieu. L’article met en avant l’intérêt de modélisations thermo-hydrauliques pour comprendre les transferts de fluides au sein de l’échantillon. Une analyse précise des résultats numériques permet de déterminer si les transferts internes sont constitués principalement d’advection d’eau liquide jusqu’à la paroi suivi par de l’évaporation, ou plutôt de l’avancée d’un front d’évaporation au sein de l’échantillon suivi par de la diffusion de la vapeur jusqu’à la paroi. [less ▲]

Hydro-mechanical modelling of the development of preferential gas pathways in claystone

in Mancuso, Claudio; Jommmi, Cristina; D'Onza, Francesca (Eds.) Unsaturated Soils: Research and Applications (volume 2) (2012)

During long-term repository of radioactive waste in argillaceous formation, the gas migration in the host formation and in the engineered barriers is a crucial issue, because it could affect the safety ... [more ▼]

During long-term repository of radioactive waste in argillaceous formation, the gas migration in the host formation and in the engineered barriers is a crucial issue, because it could affect the safety function of the clay barriers. Gas migration tests on Callovo-Oxfordian argillite have been performed by the British Geological Survey. The observations show that gas migration is often accompa-nied by the development of preferential pathways, which propagate through the sample. Hydro-mechanical numerical modelling of these tests is performed. It ap-pears that a continuum approach to the movement of gas is not sufficient to repro-duce the experimental observations. A coupling between deformation of the me-dium, permeability and air entry pressure is proposed. The numerical results show that such coupling play an important role in a successful simulation of such gas flows. [less ▲]

On the modeling of convective drying tests on soil samples in non-isothermal conditions

in Tsotsas, E.; Metzger, T.; Peglow, M. (Eds.) Proceedings of IDS 2010 - Drying 2010 (2010, October)

Study of the soil-atmosphere moisture exchanges through convective drying tests in non-isothermal conditions

in International Journal for Numerical and Analytical Methods in Geomechanics (2010), 34(12), 1297-1320

This paper deals with the moisture exchanges occurring between soils and the surrounding atmosphere. Convective drying tests are performed on Awans silts at different drying temperatures and air relative ... [more ▼]

This paper deals with the moisture exchanges occurring between soils and the surrounding atmosphere. Convective drying tests are performed on Awans silts at different drying temperatures and air relative humidities in order to reproduce the natural drying conditions. The experiments improve the understanding of the vapour transfers kinetics between the soil samples and the atmosphere. The experimental results are analysed assuming that the transfers take place in a boundary layer existing at the surface of the porous medium. The influence of the thermal conditions on the evaporation is also taken into account. In our model, coupled vapour and energy exchanges are controlled by mass and heat transfer coefficients characterizing the boundary layer. These coefficients are determined from the drying experiments. The modelling of the drying tests in non-isothermal conditions is performed in order to validate the formulation of the vapour and heat exchanges. The numerical results present a good agreement with the kinetic of the materials desaturation determined during the tests. The analysis of the moisture transport mechanisms into the sample and at the boundary shows that at the beginning of the test, the drying is first achieved by the transport of moisture in its liquid form and its evaporation at the sample outer boundary in contact with the atmosphere. In a second step, vapour diffusion becomes predominant into the sample and it corresponds to the most important decrease of relative humidity. [less ▲]

HM modelling of in-situ gas injection tests in bentonite and argillite: the PGZ experiment

in Clays in Natural and Engineered Barriers for Radioactive Waste Confinement (2010)

Characterization of vapour transfers in non isothermal conditions at cavities wall using convective drying tests

Poster (2009, September)

Convective drying tests of silts: Experimental study

in Magnan, Jean-Pierre; Cojean, Roger; Cui, Yu Jun (Eds.) International Symposium Drought and Constructions Marne-La-Vallée 1-3 Septembre 2008 (2008)

In order to determine the fluid exchanges at the galleries wall during the excavation, drying tests of soils samples are achieved in a convective micro drying rig. The results of the drying tests permit ... [more ▼]

In order to determine the fluid exchanges at the galleries wall during the excavation, drying tests of soils samples are achieved in a convective micro drying rig. The results of the drying tests permit to evaluate a mass transfer coefficient between the porous medium and the atmosphere. The influence of the drying temperature is studied. [less ▲]

Numerical Modelling of Coupled Mechanics and Gas Transfer around Radioactive Waste in Long-Term Storage

in Journal of Theoretical and Applied Mechanics (2008), 38(1-2), 25-44

During long-term storage of radioactive waste, steel containers will be corroded. This process leads to hydrogen production. A boundary value problem has been proposed to study the numerical modelling of ... [more ▼]

During long-term storage of radioactive waste, steel containers will be corroded. This process leads to hydrogen production. A boundary value problem has been proposed to study the numerical modelling of the gas migration and its coupling with the mechanical strains and stresses, under isothermal conditions. Biphasic fluid transfer model (considering water, vapour, gaseous hydrogen and dissolved hydrogen) is defined. A 2D axisymmetric case with simplified geometry close to waste disposal in clay is modelled. Fluid transport problem is first resolved. Then, coupled mechanics and fluid transfers are modelled to determine the coupling effects. [less ▲]

Numerical modelling of coupled mechanics and gas transfer

Poster (2007)