Documents disponibles écrits par cet auteur

ACMEG-T: soil thermoplasticity model / Laloui, Lyesse in Journal of engineering mechanics, Vol. 135 N° 9 (Septembre 2009) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 135 N° 9 (Septembre 2009) . - pp. 932-944 Titre : ACMEG-T: soil thermoplasticity model Type de document : texte imprimé Auteurs : Laloui, Lyesse, Auteur ; François, Bertrand, Auteur Article en page(s) : pp. 932-944 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Plasticity  Constitutive  model  Thermal  factors  Soils. Résumé : This paper addresses an advanced and unified thermomechanical constitutive model for soils. Based on experimental evidence showing the nonlinear and irreversible thermomechanical responses of saturated soils, the constitutive equations of the developed model, Advanced Constitutive Model for Environmental Geomechanics-Thermal effect (ACMEG-T), are presented. In the context of elastoplasticity and critical state theory, the model uses the multimechanism plasticity and bounding surface theory. Nonlinear thermoelasticity is joined with two coupled thermoplastic dissipative processes. The yield functions, the dissipative potentials and the plastic multipliers are introduced. Attention is particularly focused on the coupling between both plastic mechanisms, an isotropic and a deviatoric one, which are in agreement with the consistency condition for multiple dissipation. As far as isotropic mechanism is concerned, a unique thermomechanical yield surface reproduces the thermoplasticity observed at low and intermediate overconsolidation ratios, as well as the plasticity under mechanical loading in an framework unifying mechanical and thermal hardenings. Finally, the efficiency of ACMEG-T is proven by validation tests on drained and undrained thermomechanical paths. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&smode=strres [...] [article] ACMEG-T: soil thermoplasticity model [texte imprimé] / Laloui, Lyesse, Auteur ; François, Bertrand, Auteur . - pp. 932-944. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 135 N° 9 (Septembre 2009) . - pp. 932-944 Mots-clés : Plasticity  Constitutive  model  Thermal  factors  Soils. Résumé : This paper addresses an advanced and unified thermomechanical constitutive model for soils. Based on experimental evidence showing the nonlinear and irreversible thermomechanical responses of saturated soils, the constitutive equations of the developed model, Advanced Constitutive Model for Environmental Geomechanics-Thermal effect (ACMEG-T), are presented. In the context of elastoplasticity and critical state theory, the model uses the multimechanism plasticity and bounding surface theory. Nonlinear thermoelasticity is joined with two coupled thermoplastic dissipative processes. The yield functions, the dissipative potentials and the plastic multipliers are introduced. Attention is particularly focused on the coupling between both plastic mechanisms, an isotropic and a deviatoric one, which are in agreement with the consistency condition for multiple dissipation. As far as isotropic mechanism is concerned, a unique thermomechanical yield surface reproduces the thermoplasticity observed at low and intermediate overconsolidation ratios, as well as the plasticity under mechanical loading in an framework unifying mechanical and thermal hardenings. Finally, the efficiency of ACMEG-T is proven by validation tests on drained and undrained thermomechanical paths. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&smode=strres [...]

Geotechnical analysis of heat exchanger piles / Christoph Knellwolf in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 10 (Octobre 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 10 (Octobre 2011) . - pp. 890-902 Titre : Geotechnical analysis of heat exchanger piles Type de document : texte imprimé Auteurs : Christoph Knellwolf, Auteur ; Hervé Peron, Auteur ; Laloui, Lyesse, Auteur Année de publication : 2012 Article en page(s) : pp. 890-902 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Foundation  design  Pile  foundations  Temperature  effects  Heating  Cooling  Thermal  stress  Skin  friction Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : There is currently a lack of established calculation methods for the geotechnical design of heat exchanger piles, although the technology is experiencing a fast expansion. Instead of quantifying the effects of temperature changes on the static behavior of heat exchanger piles, the common geotechnical practice is to apply a large overall security factor. This is done to be on the side of safety with respect to thermal effects. The few existing in situ experiments show that applying a thermal load induces a significant change in the stress-strain state of a pile. This paper presents a geotechnical numerical analysis method based on the load-transfer approach that assesses the main effects of temperature changes on pile behavior. The method is validated on the basis of in situ measurements of the loads and deformations experienced by heat exchanger test piles. The occurrence of critical design situations is further discussed. Some conclusions are formulated on concrete failure and the full mobilization of the pile shaft friction and base resistance during the operation of the heat exchange system. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i10/p890_s1?isAuthorized=no [article] Geotechnical analysis of heat exchanger piles [texte imprimé] / Christoph Knellwolf, Auteur ; Hervé Peron, Auteur ; Laloui, Lyesse, Auteur . - 2012 . - pp. 890-902. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 10 (Octobre 2011) . - pp. 890-902 Mots-clés : Foundation  design  Pile  foundations  Temperature  effects  Heating  Cooling  Thermal  stress  Skin  friction Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : There is currently a lack of established calculation methods for the geotechnical design of heat exchanger piles, although the technology is experiencing a fast expansion. Instead of quantifying the effects of temperature changes on the static behavior of heat exchanger piles, the common geotechnical practice is to apply a large overall security factor. This is done to be on the side of safety with respect to thermal effects. The few existing in situ experiments show that applying a thermal load induces a significant change in the stress-strain state of a pile. This paper presents a geotechnical numerical analysis method based on the load-transfer approach that assesses the main effects of temperature changes on pile behavior. The method is validated on the basis of in situ measurements of the loads and deformations experienced by heat exchanger test piles. The occurrence of critical design situations is further discussed. Some conclusions are formulated on concrete failure and the full mobilization of the pile shaft friction and base resistance during the operation of the heat exchange system. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i10/p890_s1?isAuthorized=no