Documents disponibles écrits par cet auteur

Effect of soil permeability on centrifuge modeling of pile response to lateral spreading / Lenart, González in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N°1 (Janvier 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°1 (Janvier 2009) . - pp. 62–73 Titre : Effect of soil permeability on centrifuge modeling of pile response to lateral spreading Type de document : texte imprimé Auteurs : Lenart, González, Auteur ; Tarek Abdoun, Auteur ; Ricardo Dobry, Auteur Année de publication : 2009 Article en page(s) : pp. 62–73 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Centrifuge  Pile  foundations  Earthquakes  Liquefaction  Soil  permeability  Bending  moments  Limit  equilibrium Résumé : This paper presents experimental results and analysis of six model centrifuge experiments conducted on the 150g−ton Rensselaer Polytechnic Institute centrifuge to investigate the effect of soil permeability on the response of end-bearing single piles and pile groups subjected to lateral spreading. The models were tested in a laminar box and simulate a mild infinite slope with a liquefiable sand layer on top of a nonliquefiable layer. Three fine sand models consisting of a single pile, a 3×1 pile group, and a 2×2 pile group were tested, first using water as pore fluid, and then repeated using a viscous pore fluid, hence simulating two sands of different permeability in the field. The results were dramatically different, with the three tests simulating a low permeability soil developing 3–6 times larger pile head displacements and bending moments at the end of shaking. Deformation observations of colored sand strips, as well as measurements of sustained negative excess pore pressures near the foundations in the “viscous fluid” experiments, indicated that an approximately inverted conical zone of nonliquefied soil had formed in these tests at shallow depths around the foundation, which forced the liquefied soil in the free field to apply its lateral pressure against a much larger effective foundation area. Additional p-y and limit equilibrium back-analyses support the hypothesis that the greatly increased foundation bending response observed when the soil is less pervious is due to the formation of such inverted conical volume of nonliquefied sand. This study provides evidence of the importance of soil permeability on pile foundations response during lateral spreading for cases when the liquefied deposit reaches the ground surface, and suggests that bending response may be greater in silty sands than in clean sands in the field. Moreover, the observations in this study may serve as basis for realistic practical engineering methods to evaluate pile foundations subjected to lateral spreading and pressure of liquefied soil. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A1%2862 [...] [article] Effect of soil permeability on centrifuge modeling of pile response to lateral spreading [texte imprimé] / Lenart, González, Auteur ; Tarek Abdoun, Auteur ; Ricardo Dobry, Auteur . - 2009 . - pp. 62–73. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°1 (Janvier 2009) . - pp. 62–73 Mots-clés : Centrifuge  Pile  foundations  Earthquakes  Liquefaction  Soil  permeability  Bending  moments  Limit  equilibrium Résumé : This paper presents experimental results and analysis of six model centrifuge experiments conducted on the 150g−ton Rensselaer Polytechnic Institute centrifuge to investigate the effect of soil permeability on the response of end-bearing single piles and pile groups subjected to lateral spreading. The models were tested in a laminar box and simulate a mild infinite slope with a liquefiable sand layer on top of a nonliquefiable layer. Three fine sand models consisting of a single pile, a 3×1 pile group, and a 2×2 pile group were tested, first using water as pore fluid, and then repeated using a viscous pore fluid, hence simulating two sands of different permeability in the field. The results were dramatically different, with the three tests simulating a low permeability soil developing 3–6 times larger pile head displacements and bending moments at the end of shaking. Deformation observations of colored sand strips, as well as measurements of sustained negative excess pore pressures near the foundations in the “viscous fluid” experiments, indicated that an approximately inverted conical zone of nonliquefied soil had formed in these tests at shallow depths around the foundation, which forced the liquefied soil in the free field to apply its lateral pressure against a much larger effective foundation area. Additional p-y and limit equilibrium back-analyses support the hypothesis that the greatly increased foundation bending response observed when the soil is less pervious is due to the formation of such inverted conical volume of nonliquefied sand. This study provides evidence of the importance of soil permeability on pile foundations response during lateral spreading for cases when the liquefied deposit reaches the ground surface, and suggests that bending response may be greater in silty sands than in clean sands in the field. Moreover, the observations in this study may serve as basis for realistic practical engineering methods to evaluate pile foundations subjected to lateral spreading and pressure of liquefied soil. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A1%2862 [...]

New Orleans levee system performance during Hurricane Katrina / Javier Ubilla in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°5 (Mai 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°5 (Mai 2008) . - pp. 668–680 Titre : New Orleans levee system performance during Hurricane Katrina : London avenue and Orleans Canal South Type de document : texte imprimé Auteurs : Javier Ubilla, Auteur ; Tarek Abdoun, Auteur ; Inthuorn Sasanakul, Auteur Année de publication : 2008 Article en page(s) : pp. 668–680 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Levees  Hurricanes  Centrifuge  Louisiana  Floods  Damage Résumé : Hurricane Katrina was one of the worst natural disasters in U.S. history. The effects of the hurricane were particularly devastating in the city of New Orleans. Most of the damage was due to the failure of the levee system that surrounds the city to protect it from flooding. This paper presents the results of centrifuge models conducted at Rensselaer Polytechnic Institute and the U.S. Army Corps of Engineers simulating the behavior of the levees at London Avenue North and South that failed during Hurricane Katrina. Those levees failed without being overtopped by the storm surge. Also included are the results of a centrifuge model of one levee section at Orleans Canal South, which did not fail during the hurricane. The key factor of the failure mechanism of the London Avenue levees was the formation of a gap between the flooded side of the levee and the sheetpile. This gap triggered a reduction of the strength at the foundation of the protected side of the levee. The results are fully consistent with field observations. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A5%2866 [...] [article] New Orleans levee system performance during Hurricane Katrina : London avenue and Orleans Canal South [texte imprimé] / Javier Ubilla, Auteur ; Tarek Abdoun, Auteur ; Inthuorn Sasanakul, Auteur . - 2008 . - pp. 668–680. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°5 (Mai 2008) . - pp. 668–680 Mots-clés : Levees  Hurricanes  Centrifuge  Louisiana  Floods  Damage Résumé : Hurricane Katrina was one of the worst natural disasters in U.S. history. The effects of the hurricane were particularly devastating in the city of New Orleans. Most of the damage was due to the failure of the levee system that surrounds the city to protect it from flooding. This paper presents the results of centrifuge models conducted at Rensselaer Polytechnic Institute and the U.S. Army Corps of Engineers simulating the behavior of the levees at London Avenue North and South that failed during Hurricane Katrina. Those levees failed without being overtopped by the storm surge. Also included are the results of a centrifuge model of one levee section at Orleans Canal South, which did not fail during the hurricane. The key factor of the failure mechanism of the London Avenue levees was the formation of a gap between the flooded side of the levee and the sheetpile. This gap triggered a reduction of the strength at the foundation of the protected side of the levee. The results are fully consistent with field observations. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A5%2866 [...]