Documents disponibles écrits par cet auteur

Caisson foundations subjected to reverse fault rupture / M. Loli 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. 914-925 Titre : Caisson foundations subjected to reverse fault rupture : centrifuge testing and numerical analysis Type de document : texte imprimé Auteurs : M. Loli, Auteur ; I. Anastasopoulos, Auteur ; M. F. Bransby, Auteur Année de publication : 2012 Article en page(s) : pp. 914-925 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Thrust  fault  Finite  elements  3D  analysis  Caisson  foundations  Centrifuge  modeling  Soil-caisson-rupture  interaction  Tectonic  deformation Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Recent large-magnitude (M>7) earthquakes have caused numerous failures induced by surface faulting, demonstrating the need to account for tectonic deformation in seismic design. Thanks to their usually high rigidity, embedded (e.g., caisson) foundations may divert the fault rupture and lead to favorable performance, whereas surface or piled foundations may fail. We present a series of centrifuge model tests to investigate the response of caisson foundations embedded in a cohesionless soil stratum, the base of which is subjected to reverse faulting. We elucidate the interplay between the propagating fault rupture and the caisson, focusing on the role of the location of the outcropping rupture relative to the caisson. The rigid-body of the caisson causes diversion and/or bifurcation of the shear localization, which is forced to develop preferentially around the edges of the caisson. The observed failure pattern and the consequent caisson response depend strongly on the exact caisson position relative to the fault. We employed three-dimensional (3D) finite-element (FE) modeling and validated it by comparing to centrifuge test results. The numerical method captures the general interaction mechanisms, showing satisfactory (if not always perfect) agreement with experiments. We then employ the validated numerical method in a parametric investigation, providing further insight into the different possible modes of foundation response. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i10/p914_s1?isAuthorized=no [article] Caisson foundations subjected to reverse fault rupture : centrifuge testing and numerical analysis [texte imprimé] / M. Loli, Auteur ; I. Anastasopoulos, Auteur ; M. F. Bransby, Auteur . - 2012 . - pp. 914-925. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 10 (Octobre 2011) . - pp. 914-925 Mots-clés : Thrust  fault  Finite  elements  3D  analysis  Caisson  foundations  Centrifuge  modeling  Soil-caisson-rupture  interaction  Tectonic  deformation Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Recent large-magnitude (M>7) earthquakes have caused numerous failures induced by surface faulting, demonstrating the need to account for tectonic deformation in seismic design. Thanks to their usually high rigidity, embedded (e.g., caisson) foundations may divert the fault rupture and lead to favorable performance, whereas surface or piled foundations may fail. We present a series of centrifuge model tests to investigate the response of caisson foundations embedded in a cohesionless soil stratum, the base of which is subjected to reverse faulting. We elucidate the interplay between the propagating fault rupture and the caisson, focusing on the role of the location of the outcropping rupture relative to the caisson. The rigid-body of the caisson causes diversion and/or bifurcation of the shear localization, which is forced to develop preferentially around the edges of the caisson. The observed failure pattern and the consequent caisson response depend strongly on the exact caisson position relative to the fault. We employed three-dimensional (3D) finite-element (FE) modeling and validated it by comparing to centrifuge test results. The numerical method captures the general interaction mechanisms, showing satisfactory (if not always perfect) agreement with experiments. We then employ the validated numerical method in a parametric investigation, providing further insight into the different possible modes of foundation response. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i10/p914_s1?isAuthorized=no

Capacity of grillage foundations under horizontal loading / J. A. Knappett in Géotechnique, Vol. 62 N° 9 (Septembre 2012) 

Public ISBD [article]  in Géotechnique > Vol. 62 N° 9 (Septembre 2012) . - pp. 811 –823 Titre : Capacity of grillage foundations under horizontal loading Type de document : texte imprimé Auteurs : J. A. Knappett, Auteur ; M. J. Brown, Auteur ; M. F. Bransby, Auteur Année de publication : 2012 Article en page(s) : pp. 811 –823 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Sands  Footings/foundations  Offshore  engineering  Plasticity  Model  tests Résumé : Grillage foundations are an alternative to solid surface mudmats for supporting seabed infrastructure, offering improved hydrodynamic performance and savings in foundation material. Recent research has demonstrated that grillages can be designed to have similar vertical bearing capacity to a mudmat with the same footprint. This is extended herein by: (a) determining grillage performance under horizontal loading at constant vertical load (V-H); (b) the application and development of existing plasticity-based models for predicting performance; (c) comparing the V-H behaviour with surface mudmats; and (d) discussing the implications for design. Experimental tests were conducted in sands over a range of densities and in two different modes, representing different installation procedures. In over-penetrated tests, the foundations were installed to achieve a vertical bearing capacity V 0, followed by horizontal loading at a constant vertical load with V < V 0. In normally penetrated tests, foundations were installed to V 0 before horizontal loading at constant vertical load with V = V 0. Both normalised V-H yield surfaces and a plasticity-based simulation model are presented for use in design. Laboratory-scale grillages offer improved horizontal capacity in loose and medium-dense sands and similar horizontal capacity in very dense sand, compared with surface mudmats. ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.12.OG.012 [article] Capacity of grillage foundations under horizontal loading [texte imprimé] / J. A. Knappett, Auteur ; M. J. Brown, Auteur ; M. F. Bransby, Auteur . - 2012 . - pp. 811 –823. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 62 N° 9 (Septembre 2012) . - pp. 811 –823 Mots-clés : Sands  Footings/foundations  Offshore  engineering  Plasticity  Model  tests Résumé : Grillage foundations are an alternative to solid surface mudmats for supporting seabed infrastructure, offering improved hydrodynamic performance and savings in foundation material. Recent research has demonstrated that grillages can be designed to have similar vertical bearing capacity to a mudmat with the same footprint. This is extended herein by: (a) determining grillage performance under horizontal loading at constant vertical load (V-H); (b) the application and development of existing plasticity-based models for predicting performance; (c) comparing the V-H behaviour with surface mudmats; and (d) discussing the implications for design. Experimental tests were conducted in sands over a range of densities and in two different modes, representing different installation procedures. In over-penetrated tests, the foundations were installed to achieve a vertical bearing capacity V 0, followed by horizontal loading at a constant vertical load with V < V 0. In normally penetrated tests, foundations were installed to V 0 before horizontal loading at constant vertical load with V = V 0. Both normalised V-H yield surfaces and a plasticity-based simulation model are presented for use in design. Laboratory-scale grillages offer improved horizontal capacity in loose and medium-dense sands and similar horizontal capacity in very dense sand, compared with surface mudmats. ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.12.OG.012

Normal fault rupture interaction with strip foundations / I. Anastasopoulos in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N°3 (Mars 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°3 (Mars 2009) . - pp. 359–370 Titre : Normal fault rupture interaction with strip foundations Type de document : texte imprimé Auteurs : I. Anastasopoulos, Auteur ; G. Gazetas, Auteur ; M. F. Bransby, Auteur Année de publication : 2009 Article en page(s) : pp. 359–370 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Geological  faults  Soil-structure  interaction  Finite  element  method  Centrifuge  models  Seismic  effects  Foundations Résumé : Observations after earthquakes where surface fault ruptures crossed engineering facilities reveal that some structures survived the rupture almost unscathed. In some cases, the rupture path appears to divert, “avoiding” the structure. Such observations point to an interaction between the propagating rupture, the soil, and the foundation. This paper (i) develops a two-step nonlinear finite-element methodology to study rupture propagation and its interaction with strip foundations; (ii) provides validation through successful Class “A” predictions of centrifuge model tests; and (iii) conducts a parameter study on the interaction of strip foundations with normal fault ruptures. It is shown that a heavily loaded foundation can substantially divert the rupture path, which may avoid outcropping underneath the foundation. The latter undergoes rigid body rotation, often detaching from the soil. Its distress arises mainly from the ensuing loss of support that takes place either at the edges or around its center. The average pressure q on the foundation largely dictates the width of such unsupported spans. Increasing q decreases the unsupported width, reducing foundation distress. The role of q is dual: (1) it compresses the soil, “flattening” fault-induced surface “anomalies”; and (2) it changes the stress field underneath the foundation, facilitating rupture diversion. However, even if the rupture is diverted, the foundation may undergo significant stressing, depending on its position relative to the fault outcrop. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A3%2835 [...] [article] Normal fault rupture interaction with strip foundations [texte imprimé] / I. Anastasopoulos, Auteur ; G. Gazetas, Auteur ; M. F. Bransby, Auteur . - 2009 . - pp. 359–370. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°3 (Mars 2009) . - pp. 359–370 Mots-clés : Geological  faults  Soil-structure  interaction  Finite  element  method  Centrifuge  models  Seismic  effects  Foundations Résumé : Observations after earthquakes where surface fault ruptures crossed engineering facilities reveal that some structures survived the rupture almost unscathed. In some cases, the rupture path appears to divert, “avoiding” the structure. Such observations point to an interaction between the propagating rupture, the soil, and the foundation. This paper (i) develops a two-step nonlinear finite-element methodology to study rupture propagation and its interaction with strip foundations; (ii) provides validation through successful Class “A” predictions of centrifuge model tests; and (iii) conducts a parameter study on the interaction of strip foundations with normal fault ruptures. It is shown that a heavily loaded foundation can substantially divert the rupture path, which may avoid outcropping underneath the foundation. The latter undergoes rigid body rotation, often detaching from the soil. Its distress arises mainly from the ensuing loss of support that takes place either at the edges or around its center. The average pressure q on the foundation largely dictates the width of such unsupported spans. Increasing q decreases the unsupported width, reducing foundation distress. The role of q is dual: (1) it compresses the soil, “flattening” fault-induced surface “anomalies”; and (2) it changes the stress field underneath the foundation, facilitating rupture diversion. However, even if the rupture is diverted, the foundation may undergo significant stressing, depending on its position relative to the fault outcrop. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A3%2835 [...]