References of "Radu, Jean-Pol"
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See detailFractured bedrock investigation by using high-resolution borehole images and the Distributed Temperature Sensing technique
Radioti, Georgia ULg; Delvoie, Simon ULg; Radu, Jean-Pol ULg et al

in ISRM Congress 2015 Proceedings - Int’l Symposium on Rock Mechanics (2015, May)

In order to investigate the fracturing of the bedrock and its possible heterogeneous distribution in situ, four boreholes equipped with double-U geothermal pipes of 100 m long were installed on the campus ... [more ▼]

In order to investigate the fracturing of the bedrock and its possible heterogeneous distribution in situ, four boreholes equipped with double-U geothermal pipes of 100 m long were installed on the campus of the University of Liege (Liege, Belgium) over a surface area of 32 m². The bedrock, which starts at a depth approximately of 8 m, is quite fractured and consists mainly of siltstone and shale interbedded with sandstone. Different geophysical methods are applied at two different phases, after drilling the boreholes and after injecting the grouting material. The first approach consists in lowering an ultrasonic borehole imager (borehole televiewer; Zemanek, Glenn, Norton, & Caldwell, 1970), an instrument that acts as an ultrasonic transducer and receiver, into the boreholes to obtain high-resolution, continuous images with 360° coverage of the local geology and fracturing. Moreover gamma-ray logs of the four boreholes are obtained and inclinometry is conducted. After drilling the boreholes fiber optic cables are attached along the pipe loops and the double-U pipes are installed inside the boreholes. Then the grouting material is injected. The second approach consists in measuring the temperature along the fibers by applying the Distributed Temperature Sensing technique (Soto, Sahu, Faralli, Bolognini, Di Pasquale, Nebendahl, & Rueck, 2007). A laser pulse is injected into the optical fiber and the temperature along the fiber is determined by the intensity of Raman stokes and anti-stokes reemitted signals. Temperature evolution is measured during hardening of the grouting material. Local maxima of the temperature curve are probably due to a local lower thermal conductivity and/or a local larger quantity of grouting material due to gathering of fractures. A detailed fracture characterisation (position, opening, orientation, dip angle) is obtained based on the acoustic signal travel time and amplitude. The fractures are characterised by the same dipping and orientation but significantly vary in number and location in the four boreholes, despite the close distance between them. Gamma-ray data and observation of the cuttings during drilling result in rock identification through depth as well as in determination of the layer dipping. The inclination of the four boreholes tends to be perpendicular to the dipping. The combination of the two geophysical methods as presented provides information useful for the hydro-thermo-mechanical behaviour of the bedrock. The contribution of the thermal behaviour of borehole heat exchangers to bedrock investigation will be further studied by conducting Distributed Thermal Response tests (Fujii, Okubo, & Itoi, 2006). During the tests we will measure the temperature variation thanks to the installed fiber optics. These data will allow us to correlate any anisotropic thermal behaviour to the geological characteristics. The available information could be used for a detailed numerical model. [less ▲]

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See detail3D zero-thickness coupled interface finite element: Formulation and application
Cerfontaine, Benjamin ULg; Dieudonné, Anne-Catherine ULg; Radu, Jean-Pol ULg et al

in Computers and Geotechnics (2015)

In many fields of geotechnical engineering, the modelling of interfaces requires special numerical tools. This paper presents the formulation of a 3D fully coupled hydro-mechanical finite element of ... [more ▼]

In many fields of geotechnical engineering, the modelling of interfaces requires special numerical tools. This paper presents the formulation of a 3D fully coupled hydro-mechanical finite element of interface. The element belongs to the zero-thickness family and the contact constraint is enforced by the penalty method. Fluid flow is discretised through a three-node scheme, discretising the inner flow by additional nodes. The element is able to reproduce the contact/loss of contact between two solids as well as shearing/sliding of the interface. Fluid flow through and across the interface can be modelled. Opening of a gap within the interface influences the longitudinal transmissivity as well as the storage of water inside the interface. Moreover the computation of an effective pressure within the interface, according to the Terzaghi’s principle creates an additional hydro-mechanical coupling. The uplifting simulation of a suction caisson embedded in a soil layer illustrates the main features of the element. Friction is progressively mobilised along the shaft of the caisson and sliding finally takes place. A gap is created below the top of the caisson and filled with water. It illustrates the storage capacity within the interface and the transversal flow. Longitudinal fluid flow is highlighted between the shaft of the caisson and the soil. The fluid flow depends on the opening of the gap and is related to the cubic law. [less ▲]

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See detailThree-node zero-thickness hydro-mechanical interface finite element for geotechnical applications
Cerfontaine, Benjamin ULg; Dieudonné, Anne-Catherine ULg; Radu, Jean-Pol ULg et al

in Proceedings of coupled 2015 (2015)

The paper briefly presents the main features of a hydro-mechanical coupled finite element of interface. The mechanical problems takes into account the the detection of contact, the development of a ... [more ▼]

The paper briefly presents the main features of a hydro-mechanical coupled finite element of interface. The mechanical problems takes into account the the detection of contact, the development of a contact pressure, the shearing and the relative sliding between two solids. A three-node discretisation of hydraulic problem allows the representation of fluid flows across and in the plane of the interface. The method involves a drop of pressure between each side of the interface and the inner medium. The hydro-mechanical couplings come from 1) the definition of the total pressure acting on each side of the interface according to the Terzaghi’s principle; 2) the dependence of the permeability on the gap variation; 3) the variation of the fluid mass stored within the gap. [less ▲]

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See detailGas injection test in the Callovo-Oxfordian claystone: data analysis and numerical modelling
De la Vaissière, Rémi; Gerard, Pierre; Radu, Jean-Pol ULg et al

in Geological Society, London, Special Publications Online First (2014)

This paper describes a field-scale experiment on gas transport mechanisms performed at Andra’s Underground Research Laboratory (URL) in a clay rock. The experimental layout consists of two parallel ... [more ▼]

This paper describes a field-scale experiment on gas transport mechanisms performed at Andra’s Underground Research Laboratory (URL) in a clay rock. The experimental layout consists of two parallel boreholes that are equipped with multiple packer completions isolating three intervals each, which have been continuously monitoring the pore pressure evolution of the clay rock. Nitrogen gas was injected in the middle test interval of one of the boreholes at increasing rates. The entire gas test comprised six periods of controlled gas injections, each fol-lowed by a shut-in pressure recovery phase. The experimental data are presented along with their interpretation by means of numerical modelling of two-phase flow of gas and water using different numerical codes and different geometrical approaches that include axisymmetric, half-space and full 3D models. An iterative modelling process was used to show step-by-step how an accu-rate description of each component of the experiment system produced a satisfactory reproduc-tion of the experimental data and an improved understanding of the relevant phenomena. For instance, the initial volume of remaining water in the test interval, and the presence of a damaged zone around the boreholes, was important for the models to obtain good agreement with the field data. [less ▲]

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See detailAn unsaturated hydro-mechanical modelling of two in-situ experiments in Callovo-Oxfordian argillite
Charlier, Robert ULg; Collin, Frédéric ULg; Pardoen, Benoît ULg et al

in Engineering Geology (2013), 165

The unsaturated behaviour of Callovo-Oxfordian argillite is investigated through the modelling of 2 in-situ experiments. The first test studies the influence of ventilation in a gallery on the hydro ... [more ▼]

The unsaturated behaviour of Callovo-Oxfordian argillite is investigated through the modelling of 2 in-situ experiments. The first test studies the influence of ventilation in a gallery on the hydro-mechanical behaviour of the rock mass. The second test consists in a gas injection in the rock mass from an experimental borehole. A hydro-mechanical model is described and used in the modelling of the experiments. A review of the main hydro-mechanical parameters of argillite is presented. The numerical results highlight the need of a flow boundary condition reproducing the fluid transfers between the surroundings and the rock mass. The influence of dissolved gas on the compressibility of the liquid phase is also emphasised. [less ▲]

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See detailHydromechanical coupling theory in unsaturated geomaterials and its numerical integration
Charlier, Robert ULg; Radu, Jean-Pol ULg; Gerard, Pierre ULg et al

in Laloui, Lyesse (Ed.) Mechanics of Unsaturated Geomaterials (2013)

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See detailCharacterization of gas transport in low-permeability media: two-phase flow analysis of an in-situ experiment
Gerard, Pierre; Radu, Jean-Pol ULg; de la Vaissière, Rémi et al

in POROMECHANICS V: Proceedings of the Fifth Biot Conference on Poromechanics (2013)

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See detailModelling of gas migration in clay formations
Gerard, Pierre; Charlier, Robert ULg; Radu, Jean-Pol ULg et al

Conference (2013)

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See detailNumerical modelling of an in situ ventilation test in Callovo-Oxfordian claystone
Pardoen, Benoît ULg; Talandier, J.; Charlier, Robert ULg et al

Poster (2012, October)

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See detailEngineering geological mapping in Wallonia (Belgium) : present state and recent computerized approach
Delvoie, Simon ULg; Radu, Jean-Pol ULg; Ruthy, Ingrid ULg et al

Poster (2012, April)

An engineering geological map can be defined as a geological map with a generalized representation of all the components of a geological environment which are strongly required for spatial planning ... [more ▼]

An engineering geological map can be defined as a geological map with a generalized representation of all the components of a geological environment which are strongly required for spatial planning, design, construction and maintenance of civil engineering buildings. In Wallonia (Belgium) 24 engineering geological maps have been developed between the 70s and the 90s at 1/5,000 or 1/10,000 scale covering some areas of the most industrialized and urbanized cities (Liège, Charleroi and Mons). They were based on soil and subsoil data point (boring, drilling, penetration test, geophysical test, outcrop. . . ). Some displayed data present the depth (with isoheights) or the thickness (with isopachs) of the different subsoil layers up to about 50 m depth. Information about geomechanical properties of each subsoil layer,useful for engineers and urban planners, is also synthesized. However, these maps were built up only on paper and progressively needed to be updated with new soil and subsoil data. The Public Service of Wallonia and the University of Liège have recently initiated a study to evaluate the feasibility to develop engineering geological mapping with a computerized approach. Numerous and various data (about soil and subsoil) are stored into a georelational database (the geotechnical database – using Access, Microsoft®). All the data are geographically referenced. The database is linked to a GIS project (using ArcGIS, ESRI®). Both the database and GIS project consist of a powerful tool for spatial data management and analysis. This approach involves a methodology using interpolation methods to update the previous maps and to extent the coverage to new areas. The location (x, y, z) of each subsoil layer is then computed from data point. The geomechanical data of these layers are synthesized in an explanatory booklet joined to maps. [less ▲]

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See detailHydro and Hydro-Mechanical Modelling of Ventilation Test in Clayey Rocks
Pardoen, Benoît ULg; Talandier, Jean; Charlier, Robert ULg et al

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

Hydro and hydro-mechanical numerical modellings are performed in order to acquire a better understanding of clayey rock behaviour and transfers occurring during an in situ ventilation test. The test is ... [more ▼]

Hydro and hydro-mechanical numerical modellings are performed in order to acquire a better understanding of clayey rock behaviour and transfers occurring during an in situ ventilation test. The test is performed in an experimental gallery that is part of an underground research laboratory. A biphasic flow model for unsaturated soil and an elasto-plastic constitutive law are used for the host formation. The models include exchange condition of fluid mass, anisotropy and the excavation damaged zone around the gallery. Finally, the ventilation test is reproduced and the model is calibrated based on the matching between numerical results and experimental measurements. [less ▲]

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See detailGas Migration through Clay Barriers in the Context of Radioactive Waste Disposal: Numerical Modeling of an InSitu Gas Injection Test
Gerard, Pierre ULg; Radu, Jean-Pol ULg; Talandier, Jean et al

in Pijaudier-Cabot, Gilles; Pereira (Eds.) Geomechanics in CO2 Storage Facilities (2012)

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See detailModélisation numérique d’un essai de ventilation in situ
Pardoen, Benoît ULg; Talandier, Jean; Charlier, Robert ULg et al

in Skoczylas, F.; Davy, C.A.; Agostini, F. (Eds.) et al Propriétés de transfert des géomatériaux, Transfert 2012, Ecole centrale de Lille 20-22 mars 2012 (2012)

Hydro and hydro-mechanical numerical modellings are performed in order to acquire a better understanding of clayey rock behaviour and transfers occurring during an in situ ventilation test. The test is ... [more ▼]

Hydro and hydro-mechanical numerical modellings are performed in order to acquire a better understanding of clayey rock behaviour and transfers occurring during an in situ ventilation test. The test is performed in an experimental gallery that is part of an underground research laboratory. A biphasic flow model in unsaturated soil and an elasto-plastic constitutive law are used for the host formation. The models include exchange condition of fluid mass, anisotropy and the excavation damaged zone around the gallery. Finally, the ventilation test is reproduced and the model is calibrated based on the matching between numerical results and experimental measurements. [less ▲]

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See detailHydro and hydro-mechanical modelling of ventilation test in clayey rocks
Pardoen, Benoît ULg; Charlier, Robert ULg; Collin, Frédéric ULg et al

Poster (2011, October 03)

Long-term repository of radioactive waste in deep argillaceous geological media needs a good understanding of the host formation behaviour. Considering the safety function of the formation and the need of ... [more ▼]

Long-term repository of radioactive waste in deep argillaceous geological media needs a good understanding of the host formation behaviour. Considering the safety function of the formation and the need of low permeability, the behaviour of the excavation damaged zone (EDZ) is a major issue. Because drainage may modify the structure and the size of this zone, a ventilation test (SDZ) is realised by the French national radioactive waste management agency (ANDRA) in an experimental gallery of the Meuse/Haute-Marne underground research laboratory located in Callovo-Oxfordian claystone. The aim is to characterise the effect of the desaturation and possible resaturation of the damaged zone due to controlled ventilation. Numerical modellings are performed to reproduce the ventilation test. A biphasic flow model in unsaturated soil and an elasto-plastic constitutive law are used for the host formation. A nonclassical boundary condition has been developed in order to model the exchanges between the cavity and the rock. Numerical results show that it is possible to calibrate the models to obtain a satisfactory reproduction of the in situ experimental measurements and a better understanding of the fluid transfer around the gallery during the ventilation test. [less ▲]

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