Gas flow through clay barriers

Olivella, S.; Alonso, Eduardo E.

doi:10.1680/geot.2008.58.3.157

Cited by 134 publications

(81 citation statements)

References 16 publications

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“…Concerning the hydro-mechanical coupling, it is known that permeability is not homogeneous in the damaged zone. One way to model it could be to introduce a permeability modification in the localisation bands by considering a dependency with a mechanical parameter, such as strain or plastic deformation by extension of Levasseur et al (2010) or Olivella and Alonso (2008) models.…”

Section: Conclusion and Outlooksmentioning

confidence: 99%

Using Local Second Gradient Model and Shear Strain Localisation to Model the Excavation Damaged Zone in Unsaturated Claystone

2014

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The drilling of galleries induces damage propagation in the surrounding medium and creates, around them, the Excavation Damaged Zone, EDZ. The prediction of the extension and fracture structure of this zone remains a major issue especially in the context of underground nuclear waste storage. Experimental studies on geomaterials indicate that localised deformation in shear band mode usually appears prior to fractures. Thus, the excavation damaged zone can be modelled by considering the development of shear strain localisation bands. In the classical finite element framework, strain localisation suffers of a mesh-dependency problem. Therefore, an enhanced model with a regularisation method is required to correctly model the strain localisation behaviour. Among the existing methods, we choose the coupled local second gradient model. We extend it to unsaturated conditions and we include the solid grain compressibility. Furthermore, air ventilation inside underground galleries engenders a rock-atmosphere interaction that could influence the damaged zone. This interaction has to be investigated in order to predict the damaged zone behaviour. Finally, a hydro-mechanical modelling of a gallery excavation in claystone is presented and leads to a fairly good representation of the EDZ. The main objectives of this study are to model the fractures by considering shear strain localisation bands and to investigate if an isotropic model accurately reproduces the in situ measurements. The numerical results provide information about the damaged zone extension, structure and behaviour that are in very good agreement with in situ measurements and observations. For instance, the strain localisation bands develop in chevron pat-B. Pardoen * · S. Levasseur · F. Collin Université de Liège, Département ArGEnCo, Chemin des Chevreuils 1, 4000 Liège, Belgium Tel.: +32-4-3662033 E-mail: b.pardoen@ulg.ac.be * FRIA, F.R.S.-FNRS scholarship holder tern during the excavation and rock desaturation is observed close to the gallery due to air ventilation.

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Section: Conclusion and Outlooksmentioning

confidence: 99%

Using Local Second Gradient Model and Shear Strain Localisation to Model the Excavation Damaged Zone in Unsaturated Claystone

2014

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“…An evolution of the hydraulic permeability in the shear bands can be 945 added in the model (Pardoen et al, 2014(Pardoen et al, , 2015b by considering a dependency with a mechanical parameter (Olivella & Alonso, 2008).…”

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Shear banding modelling in cross-anisotropic rocks

Pardoen

Seyedi²,

Collin

2015

International Journal of Solids and Structures

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Sedimentary geomaterials such as rocks frequently exhibit cross-anisotropic properties and their behaviour depends on the direction of loading with respect to their microstructure. As far as material rupture is concerned, localised deformation in shear band mode appears generally before cracks and material failure. cavation fractured zone that develops around a gallery is strongly influenced by the material anisotropy.

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“…Finally, such results show that a predictive model as two-phase flow approach is able to reproduce experimental observations in large scale system, as far as the injection flow rate and the gas pressures remain moderate. Taking into account the development of gas preferential pathways is certainly a crucial issue in the description of laboratory experiment (Olivella & Alonso, 2008;Gerard et al, 2012b), but seems to be negligible for these experimental conditions.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Gas Transport in Low-Permeability Media: Two-Phase Flow Analysis of an In-Situ Experiment

et al. 2013

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This paper describes a field-scale experiment on gas transport mechanisms performed at the Andra Underground Research Laboratory in a clay rock. The experimental layout consists of two parallel boreholes that are equipped with multiple packer completions delimiting three intervals each and which monitor continuously the pore pressure evolution of the clay rock. Nitrogen gas is injected in the middle test interval of one of the boreholes at increasing constant rates. The experimental data collected so far are presented along with their interpretation by means of 1D and 3D numerical modeling of the boundary value problem. The numerical results show that a predictive model as two-phase flow approach is able to reproduce experimental observations in large scale system, as far as the injection flow rate and the gas pressures remain moderate. Moreover permeability is not modified by gas injection, which indicates that the rock mass is not damaged by the gas pressure increase during the test.

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Gas flow through clay barriers

Cited by 134 publications

References 16 publications

Using Local Second Gradient Model and Shear Strain Localisation to Model the Excavation Damaged Zone in Unsaturated Claystone

Using Local Second Gradient Model and Shear Strain Localisation to Model the Excavation Damaged Zone in Unsaturated Claystone

Shear banding modelling in cross-anisotropic rocks

Characterization of Gas Transport in Low-Permeability Media: Two-Phase Flow Analysis of an In-Situ Experiment

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