References of "Radu, Jean-Pol"
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See detailRétention et transfert des pollutions chimiques solubles : mécanismes fondamentaux et modélisation numérique
Charlier, Robert ULg; Radu, Jean-Pol ULg

in Delage, Pierre; Schrefler, Bernard (Eds.) Géomécanique Environnementale – sols pollués et déchets (2005)

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See detailNumerical mdeling of hydro-mechanical fracture behaviour
Guiducci, Chiara; Collin, Frédéric ULg; Radu, Jean-Pol ULg et al

Conference (2003)

A numerical approach for modeling coupled Hydro-Mechanical fracture behavior in 2D is presented in this paper. This approach accounts for the strong dependence of the flow characteristics on fracture ... [more ▼]

A numerical approach for modeling coupled Hydro-Mechanical fracture behavior in 2D is presented in this paper. This approach accounts for the strong dependence of the flow characteristics on fracture apertures and offers an anisotropic description of the flow propagation in the fracture. An interface finite element and a constitutive model are developed . In order to validate the applicability of the model to general geomechanic problems, 2D simulations were performed. Results show the good application of the mathematical model and the fundamental hydraulic role played by the fractures. [less ▲]

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See detailThermo-hydro-mechanical coupling in clay barriers
Collin, Frédéric ULg; Li, Xian-Ling; Radu, Jean-Pol ULg et al

in Engineering Geology (2002), 64(2-mars Sp. Iss. SI),

A thermo-hydro-mechanical model is presented to tackle the complex coupling problems encountered in clay barriers. A detailed formulation. coupling heat, moisture (liquid water and water vapour) and air ... [more ▼]

A thermo-hydro-mechanical model is presented to tackle the complex coupling problems encountered in clay barriers. A detailed formulation. coupling heat, moisture (liquid water and water vapour) and air transfer in a deformable unsaturated soil is given. The formulation of Alonso-Gens' mechanical model for unsaturated soil is also incorporated. Finally, a small-scale wetting-heating test on compacted bentonite is performed for validation; the numerical results are compared to the experimental measurements. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailNumerical modeling of hydro-mechanical fracture behavior
Guiducci, Chiara; Pellegrino, Antonio; Radu, Jean-Pol ULg et al

in Pande, G. N.; Pietruszczak, S. (Eds.) Numerical models in Geomechanics (2002)

A numerical approach for modeling coupled hydro-mechanical fracture behavior is proposed. The movement of fluids through rock fractures is important in many engineering areas of practical interest such as ... [more ▼]

A numerical approach for modeling coupled hydro-mechanical fracture behavior is proposed. The movement of fluids through rock fractures is important in many engineering areas of practical interest such as those ones of petroleum and mining engineering. In that context, one of the most investigated and complex subjects is the effect on well productivity due to changes in hydraulic conductivity both on the matrix rock and on its main fractures. It is well known, that these flow characteristics are strongly controlled by fracture apertures. Recent investigations on the distribution of the apertures in natural fractures suggest that the cubic law can, better than the Darcy law, predict the fluid flux through rough walled fractures as long as the appropriate average fracture aperture is used. A finite element code is developed to predict the influence that the stresses variation in the soil has on the distributed hydraulic conductivity field. The proposed model combines the stochastic cubic law with a non-linear deformation function (hyperbolic) that is suggested to describe the stress-closure/opening curves of the joints and that allows to couple together the hydraulic and the mechanic fracture behavior. The relationships used and the validity of the present model are tested through comparison between experimental data and numerical predictions (Bart 2000) in various boundary and loading conditions. Comparison between the Darcy model governing fluid flow equation and linear stress-closure/opening relation has also been performed showing the differences and the better de-scription given by the proposed new model. [less ▲]

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See detailHydro-mechanical behavior of fractures: 2D, F.E.M. modeling
Guiducci, Chiara; Pellegrino, Antonio; Radu, Jean-Pol ULg et al

in Auriault, J. L.; Geindreau, C.; Royer, P. (Eds.) Poromechanics II (2002)

A numerical approach for modeling the coupled hydro-mechanical fracture behavior is proposed. The movement of fluids through rock fractures and consequently the evolution of their hydraulic conductivity ... [more ▼]

A numerical approach for modeling the coupled hydro-mechanical fracture behavior is proposed. The movement of fluids through rock fractures and consequently the evolution of their hydraulic conductivity is an important subject in many petroleum related activities, mainly concerning the change of well productivity during the reservoir life. It is well known that the flow in the fractures is strongly controlled by the fracture apertures. Recent investigations on the distribution of the apertures in natural fractures suggest that the cubic law can, better than the Darcy law, predict the fluid flux through rough walled fractures as long as the appropriate average fracture aperture is used. A finite element code is developed to predict the influence that the stresses variation in the fracture has on the distributed hydraulic conductivity field. The proposed model combines the stochastic cubic law with a non-linear deformation function (hyperbolic) that is suggested to describe the stress-closure/opening curves of the joints and that allows to couple together the hydraulic and the mechanic fracture behavior. The relationships used and the validity of the present model are tested by means of the comparison between experimental data and numerical predictions (Bart 2000) in various bound-ary and loading conditions. Comparisons between the proposed new model and a no coupled one have also been performed. They show that the proposed coupled model allows for a more realistic description of the fracture behavior. [less ▲]

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See detailCellulose enzymatic availability in waste refuse
Rodriguez, C.; Hiligsmann, Serge ULg; Lardinois, M. et al

in Christensen; Cossu; Stegmann (Eds.) Proceedings Sardinia 01, Eight International Waste Management and Landfill Symposium (2001)

This work presents an original method for testing the biological reactivity of cellulose. This test specifically targets one of the limiting steps of cellulose bioconversion into biogas, i.e. the ... [more ▼]

This work presents an original method for testing the biological reactivity of cellulose. This test specifically targets one of the limiting steps of cellulose bioconversion into biogas, i.e. the cellulose hydrolysis. From this point of view, enzymes-mediated hydrolysis has been performed to evaluate cellulose bioavailability in refuse samples from different layers of an old landfill. The relationship between the cellulose enzymatic accessibility and the lignin contents has also been studied. Similarly, the correlation between cellulose, lignin and humic acid contents has been investigated. On the other hand, moisture content in landfills is considered as one of the most important factors that favours methanogenesis. In this respect, the influence of moisture content on cellulose enzymatic hydrolysis has also been evaluated. [less ▲]

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See detailA pluridisciplinary model to predict municipal landfill life
Hiligsmann, Serge ULg; Rodriguez, C.; Lardinois, M. et al

Conference (2001)

Most degradation processes that occur within municipal wastes landfills result from different microbial activities interacting all along the landfill lifetime and that are influenced by several non ... [more ▼]

Most degradation processes that occur within municipal wastes landfills result from different microbial activities interacting all along the landfill lifetime and that are influenced by several non-biological factors. These complex biological and chemical processes require a multidisciplinary pattern in order to assess and control their environmental impact. Thanks to Walloon Region support, we have developed a pattern or model combining the evolution of different key parameters. Such parameters qualify biogas (composition, production rate), leachate (pH, BOD5, COD, volatile fatty acids, redox potential, nitrogen balance, humic acids...), or solid waste (moisture, settlement, cellulose content...). This paper presents relationships, including our model, between these parameters. Variations of pH, BOD5/COD ratio, sulfate concentration in leachates, gas composition analysis and settlement measures allow to predict landfill age, on a standard scale, since completion. Evaluation of cellulose and water content in refuse as well as settlement degree are useful to estimate the time required for complete biological degradation. [less ▲]

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See detailOil field subsidence phenomena
Charlier, Robert ULg; Schroeder, Christian ULg; Radu, Jean-Pol ULg et al

in Revue Française de Génie Civil (2001), 5(6), 857-866

Subsidence of an chalky oil field is described. The mechanical behaviour of the chalk partly saturated by oil and water is described and allows to model the compaction occurring within a simple reservoir ... [more ▼]

Subsidence of an chalky oil field is described. The mechanical behaviour of the chalk partly saturated by oil and water is described and allows to model the compaction occurring within a simple reservoir model during the depletion as well as during the water injection. [less ▲]

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See detailNumerical modelling of coupled transient phenomena
Charlier, Robert ULg; Radu, Jean-Pol ULg; Collin, Frédéric ULg

in Revue Française de Génie Civil (2001), 5(6), 719-743

The basic phenomena involved in thermo-hydro-mechanical processes in geomaterials have been described in the 1st chapter. The equations describing these phenomena are non-linear differential equations ... [more ▼]

The basic phenomena involved in thermo-hydro-mechanical processes in geomaterials have been described in the 1st chapter. The equations describing these phenomena are non-linear differential equations. Their solution can generally only be approximated thanks to numerical methods. This is the main subject of the present chapter. First the type of problems and the set of equations to be solved will be shortly recalled. Emphasis will be given on the non-linear contributions. In a second section, the mostly developed numerical method, i.e. the finite difference and the finite element methods will be discussed under the light of the problems to be treated. The iterative techniques allowing the solution of non linear equations will be described. A third section will be dedicated to the coupling terms and to their modelling. The question that rises then is How to model efficiently problems, which may differ highly from, the point of view of the time and length scales? [less ▲]

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See detailClay barriers assesment : a coupled mechanical and moisture transfert model
Collin, Frédéric ULg; Li, Xian; Radu, Jean-Pol ULg et al

(1999)

A thermo-hydro-mechanical model is presented to tackle the complex coupling problems encountered in clay barriers. A detailed formulation coupling the heat, moisture (liquid water and water vapour) and ... [more ▼]

A thermo-hydro-mechanical model is presented to tackle the complex coupling problems encountered in clay barriers. A detailed formulation coupling the heat, moisture (liquid water and water vapour) and, air transfer in a deformable unsaturated soil is given. The formulation of the Alonso-Gens’s mechanical model for unsaturated soil is also incorporated. The sensitivity to some parameters and their determinations are analysed. Finally, a small scale wetting – heating test on compacted bentonite is performed for validation; the numerical results are compared to the experimental measurements. [less ▲]

Detailed reference viewed: 24 (6 ULg)
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See detailA biological pluridisciplinary model to predict municipal landfill life
Steyer, E.; Hiligsmann, Serge ULg; Radu, Jean-Pol ULg et al

in Christensen; Cossu; Stegmann (Eds.) Proceedings Sardinia 99, Seventh International Waste Management and Landfill Symposium (1999)

The degradation processes occurring within landfills are the keys to assessment and control of their environmental impact. This degradation results from different microbial activities interacting all ... [more ▼]

The degradation processes occurring within landfills are the keys to assessment and control of their environmental impact. This degradation results from different microbial activities interacting all along the landfill lifetime and influenced by several non-biological factors. Approaching these complex biological and chemical processes requires a multidisciplinary pattern. Thanks to Walloon Region support, we have developed a pattern or model combining the evolution of different key parameters. Such parameters qualify biogas (composition, production rate), leachate (pH, BOD5, COD, volatile fatty acids, redox potential, nitrogen balance, humic acids...), or solid waste (moisture, settlement, cellulose content...). This paper presents relationships, including our model, between these parameters. Variations of pH, BOD5/COD ratio, sulphate concentration in leachates and settlement measures allows to predict landfill age since completion. Evaluation of cellulose and water content in refuse as well as settlement degree are useful to estimate the time required for complete biological degradation. The mathematical model has also been applied, with success, to the case of Anton Sclayn site. [less ▲]

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See detailComparisons of anisotropic elastoplastic laws applied to steel sheet
Habraken, Anne ULg; Radu, Jean-Pol ULg; Duchene, Laurent ULg et al

in International Conference NUMIFORM 1998 (1998, June)

Detailed reference viewed: 14 (10 ULg)
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See detailThermo-hydro-mechanical coupling in clay barriers
Collin, Frédéric ULg; Li, Xian; Radu, Jean-Pol ULg et al

Conference (1998)

A thermo-hydro-mechanical model is presented to tackle the complex coupling problems encountered in clay barriers. A detailed formulation coupling the heat, moisture (liquid water and water vapour) and ... [more ▼]

A thermo-hydro-mechanical model is presented to tackle the complex coupling problems encountered in clay barriers. A detailed formulation coupling the heat, moisture (liquid water and water vapour) and, air transfer in a deformable unsaturated soil is given. The formulation of the Alonso-Gens’s mechanical model for unsaturated soil is also incorporated. The sensitivity to some parameters and their determinations are analysed. Finally, a small scale wetting – heating test on compacted bentonite is performed for validation; the numerical results are compared to the experimental measurements. [less ▲]

Detailed reference viewed: 17 (4 ULg)
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See detailThermo-hydro-mechanical coupling in clay barriers
Li, Xian; Collin, Frédéric ULg; Radu, Jean-Pol ULg et al

in Evangelista, Aldo; Picarelli, Luciano (Eds.) The Geotechnics of Hard soils, Soft Rocks (1998)

A complete thermo-hydro-mechanical model is presented to tackle the complex coupling problems encountered in clay barriers. A detailed formulation coupling the heat, moisture (liquid water and water ... [more ▼]

A complete thermo-hydro-mechanical model is presented to tackle the complex coupling problems encountered in clay barriers. A detailed formulation coupling the heat, moisture (liquid water and water vapour) and, air transfer in a deformable unsaturated soil is given. The formulation of the Alonso-Gens’s mechanical model for unsaturated soil is also incorporated. The sensitivity to some parameters and their determinations are analysed. Finally, a small scale wetting – heating test on compacted bentonite is performed for validation; the numerical results are compared to the experimental measurements. [less ▲]

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See detailThermo-hydro-mechanical coupling in clay barriers
Collin, Frédéric ULg; Li, Xiang Ling; Charlier, Robert ULg et al

in Thimus, Jean-Francois; Abousleiman, Y.; Cheng, A. H. D. (Eds.) et al Poromechanics. A tribute to Maurice A. Biot (1998)

A complete thermo-hydro-mechanical model is presented to treat the complex coupling problems in the clay barrier. The formulation related to the heat transfer, moisture transfer (liquid water and water ... [more ▼]

A complete thermo-hydro-mechanical model is presented to treat the complex coupling problems in the clay barrier. The formulation related to the heat transfer, moisture transfer (liquid water and water vapour), air transfer in a deformable unsaturated soil is given. The formulation of the Alonso-Gens’s mechanical model for unsaturated soil is also incorporated. Finally, a small scale wetting – heating test on compacted bentonite is performed as a validation test. The numerical results are compared with respect to the experimental measurements. [less ▲]

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See detailWater movement effect on the strain localisation during a biaxial compression
Charlier, Robert ULg; Radu, Jean-Pol ULg; Barnichon, J. D.

in Proc. of NUMOG VI (1997, July)

Detailed reference viewed: 7 (6 ULg)
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See detailHydromechanical coupling and strain localisation
Charlier, Robert ULg; Radu, Jean-Pol ULg

in Proc. of the NAFEMS World Congress (1997, April)

Detailed reference viewed: 6 (2 ULg)