Modelling the axial soil resistance on deep-water pipelines / M. F. Randolph in Géotechnique, Vol. 62 N° 9 (Septembre 2012)  

Public ISBD [article]  inGéotechnique > Vol. 62 N° 9 (Septembre 2012) . - pp. 837 –846 Titre : Modelling the axial soil resistance on deep-water pipelines Type de document : texte imprimé Auteurs : M. F. Randolph, Auteur ; D. J. White, Auteur ; Y. Yan, Auteur Année de publication : 2012 Article en page(s) : pp. 837 –846 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Friction Theoretical analysis Pipelines Offshore engineering Résumé : Axial pipe–soil resistance is an important aspect of deep-water pipeline design, since it influences the longitudinal and lateral buckling responses under thermally induced expansion and contraction of the pipeline. Experimental evidence has shown that the axial resistance, expressed as a proportion of the submerged pipeline weight, can vary by an order of magnitude, depending on the rate of axial movement and cumulative time. This paper provides a theoretical framework for assessing the magnitude of axial friction. The framework is developed within a critical-state context using effective stresses, applicable to any degree of drainage in the soil, quantifying the magnitude and duration of excess pore pressures generated near the pipe/soil interface. Two other aspects of behaviour are added to match the observed velocity dependence of axial resistance: (a) a damage term, leading to contractive volumetric strain at the interface; and (b) strain-rate dependence of the mobilised soil strength. Analytical expressions are derived that capture the above features of the response. The resulting variations of normalised frictional resistance with time and velocity are then shown to match experimental data from interface shear-box tests, representing a planar idealisation of the same behaviour, and from model pipe tests. ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.12.OG.010 [article] Modelling the axial soil resistance on deep-water pipelines [texte imprimé] / M. F. Randolph, Auteur ; D. J. White, Auteur ; Y. Yan, Auteur . - 2012 . - pp. 837 –846. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 62 N° 9 (Septembre 2012) . - pp. 837 –846 Mots-clés : Friction Theoretical analysis Pipelines Offshore engineering Résumé : Axial pipe–soil resistance is an important aspect of deep-water pipeline design, since it influences the longitudinal and lateral buckling responses under thermally induced expansion and contraction of the pipeline. Experimental evidence has shown that the axial resistance, expressed as a proportion of the submerged pipeline weight, can vary by an order of magnitude, depending on the rate of axial movement and cumulative time. This paper provides a theoretical framework for assessing the magnitude of axial friction. The framework is developed within a critical-state context using effective stresses, applicable to any degree of drainage in the soil, quantifying the magnitude and duration of excess pore pressures generated near the pipe/soil interface. Two other aspects of behaviour are added to match the observed velocity dependence of axial resistance: (a) a damage term, leading to contractive volumetric strain at the interface; and (b) strain-rate dependence of the mobilised soil strength. Analytical expressions are derived that capture the above features of the response. The resulting variations of normalised frictional resistance with time and velocity are then shown to match experimental data from interface shear-box tests, representing a planar idealisation of the same behaviour, and from model pipe tests. ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.12.OG.010

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Soret effect for a ternary mixture in porous cavity / T. J. Jaber in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008)  

Public ISBD [article]  inTransactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 9 p. Titre : Soret effect for a ternary mixture in porous cavity : modeling with variable diffusion coefficients and viscosity Type de document : texte imprimé Auteurs : T. J. Jaber, Auteur ; Y. Yan, Auteur ; M. Z. Saghir, Auteur Année de publication : 2009 Article en page(s) : 9 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Diffusion (physics)  permeability  viscosity  cavities  thermal diffusion  temperature  methane  convection Résumé : A porous cavity filled with methane (C1), n-butane (nC4), and dodecane (C12) at a pressure of 35.0MPa is used to investigate numerically the flow interaction due to the presence of thermodiffusion and buoyancy forces. A lateral heating condition is applied with the left wall maintained at 10°C and the right wall at 50°C. The molecular diffusion and thermal diffusion coefficients are functions of temperature, concentration, and viscosity of mixture components. It has been found that for permeability below 200md the thermodiffusion is dominant; and above this level, buoyancy convection becomes the dominant mechanism. The variation of viscosity plays an important role on the molecular and thermal diffusion. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Soret effect for a ternary mixture in porous cavity : modeling with variable diffusion coefficients and viscosity [texte imprimé] / T. J. Jaber, Auteur ; Y. Yan, Auteur ; M. Z. Saghir, Auteur . - 2009 . - 9 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 9 p. Mots-clés : Diffusion (physics)  permeability  viscosity  cavities  thermal diffusion  temperature  methane  convection Résumé : A porous cavity filled with methane (C1), n-butane (nC4), and dodecane (C12) at a pressure of 35.0MPa is used to investigate numerically the flow interaction due to the presence of thermodiffusion and buoyancy forces. A lateral heating condition is applied with the left wall maintained at 10°C and the right wall at 50°C. The molecular diffusion and thermal diffusion coefficients are functions of temperature, concentration, and viscosity of mixture components. It has been found that for permeability below 200md the thermodiffusion is dominant; and above this level, buoyancy convection becomes the dominant mechanism. The variation of viscosity plays an important role on the molecular and thermal diffusion. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

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