Documents disponibles écrits par cet auteur

Mechanical behaviour of gas-charged marine plastic sediments / N. Sultan in Géotechnique, Vol. 62 N° 9 (Septembre 2012) 

Public ISBD [article]  in Géotechnique > Vol. 62 N° 9 (Septembre 2012) . - pp. 751 –766 Titre : Mechanical behaviour of gas-charged marine plastic sediments Type de document : texte imprimé Auteurs : N. Sultan, Auteur ; V. De Gennaro, Auteur ; A. Puech, Auteur Année de publication : 2012 Article en page(s) : pp. 751 –766 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Constitutive  relations  Offshore  engineering  Plasticity  Compressibility  Shear  strength Résumé : Understanding how free gas modifies the mechanical behaviour of marine plastic sediments remains a challenging issue. Special triaxial tests were carried out on natural sediments recovered from the Gulf of Guinea. Special attention was devoted to the laboratory preparation procedure, involving saturation of natural marine sediment samples with carbonated water and generation of free gas following undrained unloading. Experimental data show that soil destructuration and damage generated by gas expansion and exsolution are at the origin of (a) the increase in the isotropic compressibility and decrease in the preconsolidation pressure, and (b) the decrease in the peak undrained strength and abrupt increase of the pore pressure during undrained shearing. The experimental data also show that flooding of gas bubbles and dissolution of free gas do not imply a complete strength recovery of natural sediments. ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.12.OG.002 [article] Mechanical behaviour of gas-charged marine plastic sediments [texte imprimé] / N. Sultan, Auteur ; V. De Gennaro, Auteur ; A. Puech, Auteur . - 2012 . - pp. 751 –766. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 62 N° 9 (Septembre 2012) . - pp. 751 –766 Mots-clés : Constitutive  relations  Offshore  engineering  Plasticity  Compressibility  Shear  strength Résumé : Understanding how free gas modifies the mechanical behaviour of marine plastic sediments remains a challenging issue. Special triaxial tests were carried out on natural sediments recovered from the Gulf of Guinea. Special attention was devoted to the laboratory preparation procedure, involving saturation of natural marine sediment samples with carbonated water and generation of free gas following undrained unloading. Experimental data show that soil destructuration and damage generated by gas expansion and exsolution are at the origin of (a) the increase in the isotropic compressibility and decrease in the preconsolidation pressure, and (b) the decrease in the peak undrained strength and abrupt increase of the pore pressure during undrained shearing. The experimental data also show that flooding of gas bubbles and dissolution of free gas do not imply a complete strength recovery of natural sediments. ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.12.OG.002

Yielding and plastic behaviour of Boom clay / N. Sultan in Géotechnique, Vol. 60 N° 9 (Septembre 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 9 (Septembre 2010) . - pp. 657–666 Titre : Yielding and plastic behaviour of Boom clay Type de document : texte imprimé Auteurs : N. Sultan, Auteur ; Y.-J. Cui, Auteur ; P. Delage, Auteur Année de publication : 2011 Article en page(s) : pp. 657–666 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Laboratory  tests  Plasticity  Clays  Anisotropy  Elasticity  Constitutive  relations  Shear  strength Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An underground research laboratory (URL) has been excavated in a deposit of Boom clay at a depth of 223 m by the SCK-CEN Belgian organisation near the city of Mol. This URL is devoted to research into nuclear waste disposal. This paper presents the results of an investigation carried out in the triaxial apparatus on specimens that were trimmed from blocks extracted during excavation sequences in the URL. In order to characterise the mechanical behaviour of the natural Boom clay and to examine the effect of initial and induced anisotropy on its constitutive behaviour, two series of triaxial tests were carried out. Special attention was devoted to the yield behaviour and the effects of stress history. Experimental results showed a clear relation between the shape of yield curves and stress history. The yield curve of the clay in its initial state was oriented along the K 0 line, illustrating the anisotropy of fabric that was generated during the soil deposition. Subsequent isotropic compression (up to 9 MPa) made the yield curve more and more oriented along the p′ axis. Based on these experimental results, an elasto-plastic model accounting for isotropic and anisotropic hardening in (p′:q) space was developed. The initial yield curve of the soil was taken inclined with respect to the p′ axis. The formulation proposed describes the change in shape, size and orientation of the yield curve, according to the stress history. Eight constitutive parameters were used to describe the anisotropic behaviour of the soil. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.7.00142 [article] Yielding and plastic behaviour of Boom clay [texte imprimé] / N. Sultan, Auteur ; Y.-J. Cui, Auteur ; P. Delage, Auteur . - 2011 . - pp. 657–666. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 9 (Septembre 2010) . - pp. 657–666 Mots-clés : Laboratory  tests  Plasticity  Clays  Anisotropy  Elasticity  Constitutive  relations  Shear  strength Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An underground research laboratory (URL) has been excavated in a deposit of Boom clay at a depth of 223 m by the SCK-CEN Belgian organisation near the city of Mol. This URL is devoted to research into nuclear waste disposal. This paper presents the results of an investigation carried out in the triaxial apparatus on specimens that were trimmed from blocks extracted during excavation sequences in the URL. In order to characterise the mechanical behaviour of the natural Boom clay and to examine the effect of initial and induced anisotropy on its constitutive behaviour, two series of triaxial tests were carried out. Special attention was devoted to the yield behaviour and the effects of stress history. Experimental results showed a clear relation between the shape of yield curves and stress history. The yield curve of the clay in its initial state was oriented along the K 0 line, illustrating the anisotropy of fabric that was generated during the soil deposition. Subsequent isotropic compression (up to 9 MPa) made the yield curve more and more oriented along the p′ axis. Based on these experimental results, an elasto-plastic model accounting for isotropic and anisotropic hardening in (p′:q) space was developed. The initial yield curve of the soil was taken inclined with respect to the p′ axis. The formulation proposed describes the change in shape, size and orientation of the yield curve, according to the stress history. Eight constitutive parameters were used to describe the anisotropic behaviour of the soil. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.7.00142