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Analyzing liquefaction-induced lateral spreads using strength ratios / Scott M. Olson in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°8 (Août 2008) . - pp. 1035–1049 Titre : Analyzing liquefaction-induced lateral spreads using strength ratios Type de document : texte imprimé Auteurs : Scott M. Olson, Auteur ; Cora I. Johnson, Auteur Année de publication : 2008 Article en page(s) : pp. 1035–1049 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Liquefaction  Shear  strength  Penetration  resistance  In  situ  tests  Earthquakes  Lateral  displacement Résumé : The writers backanalyzed 39 well-documented liquefaction-induced lateral spreads in terms of a mobilized strength ratio, su(mob)∕σ′vo using the Newmark sliding block method. Based on the inverse analyses results, we found that the backcalculated strength ratios mobilized during lateral spreads can be directly correlated to normalized cone penetration test tip resistance and standard penetration test blow count. Remarkably, Newmark analysis-based strength ratios mobilized during these lateral spreads essentially coincide with liquefied strength ratios backcalculated from liquefaction flow failures. The mobilized strength ratios appear to be independent of the magnitude of lateral displacement (at least for displacements greater than 15cm ) and the strength of shaking (in terms of peak ground acceleration). Furthermore, the mobilized strength ratios backcalculated from these cases appear to be consistent for a given depositional environment and do not appear to be severely impacted by potential water layer formation. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A8%2810 [...] [article] Analyzing liquefaction-induced lateral spreads using strength ratios [texte imprimé] / Scott M. Olson, Auteur ; Cora I. Johnson, Auteur . - 2008 . - pp. 1035–1049. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°8 (Août 2008) . - pp. 1035–1049 Mots-clés : Liquefaction  Shear  strength  Penetration  resistance  In  situ  tests  Earthquakes  Lateral  displacement Résumé : The writers backanalyzed 39 well-documented liquefaction-induced lateral spreads in terms of a mobilized strength ratio, su(mob)∕σ′vo using the Newmark sliding block method. Based on the inverse analyses results, we found that the backcalculated strength ratios mobilized during lateral spreads can be directly correlated to normalized cone penetration test tip resistance and standard penetration test blow count. Remarkably, Newmark analysis-based strength ratios mobilized during these lateral spreads essentially coincide with liquefied strength ratios backcalculated from liquefaction flow failures. The mobilized strength ratios appear to be independent of the magnitude of lateral displacement (at least for displacements greater than 15cm ) and the strength of shaking (in terms of peak ground acceleration). Furthermore, the mobilized strength ratios backcalculated from these cases appear to be consistent for a given depositional environment and do not appear to be severely impacted by potential water layer formation. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A8%2810 [...]

Sequential analysis of ground movements at three deep excavation sites with mixed ground profiles / Seo, Min-Woo in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 5 (Mai 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 5 (Mai 2010) . - pp. 656-668 Titre : Sequential analysis of ground movements at three deep excavation sites with mixed ground profiles Type de document : texte imprimé Auteurs : Seo, Min-Woo, Auteur ; Scott M. Olson, Auteur ; Ku Seung Yang, Auteur Année de publication : 2010 Article en page(s) : pp. 656-668 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Excavation  Settlement  Lateral  displacement  Diaphragm  wall  Bracing  Anchors  Residual  soils  Bedrock Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Field measurements of settlement and lateral deformation obtained from three deep excavation sites constructed in mixed ground profiles are presented and analyzed. Settlement measurements were obtained throughout the construction process, categorized in three stages as: (1) preexcavation (i.e., preliminary site work and support wall installation); (2) main excavation and bracing/anchor installation; and (3) postexcavation (i.e., removal of bracing as basement construction proceeds). Maximum preexcavation stage settlements of 0.03%Hw to 0.06%Hw (where Hw = wall or trench depth) were measured at two sites, with the maximum settlements occurring adjacent to the wall during its installation. Maximum ground surface settlements during the main excavation stage ranged from about 0.15%He to 0.30%He (where He = final excavation depth) and the distribution of ground settlement extended to a distance of 1.5He to 2.0He from the wall. Maximum settlements occurred at distances of about 0.3He to 0.5He from the wall at two sites where the wall consisted of concrete cast in situ (concrete diaphragm and concrete secant pile walls), creating a significant reverse curvature in the settlement distribution. The maximum postexcavation stage settlements ranged from 0.07%He to 0.10%He for the three sites, representing roughly 10 to 60% increases in settlement over the main excavation settlements, depending greatly on the specific support removal methods as well as the basement floor construction details employed at an individual site. Lateral deflections during the main excavation stage were consistent with trends reported in the literature, ranging from 0.12%He to 0.23%He, while lateral movement during postexcavation stage ranged from 0.03%He to 0.09%He. Finally, the settlements measured during the main and postexcavation stages are related to the support system stiffness. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i5/p656_s1?isAuthorized=no [article] Sequential analysis of ground movements at three deep excavation sites with mixed ground profiles [texte imprimé] / Seo, Min-Woo, Auteur ; Scott M. Olson, Auteur ; Ku Seung Yang, Auteur . - 2010 . - pp. 656-668. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 5 (Mai 2010) . - pp. 656-668 Mots-clés : Excavation  Settlement  Lateral  displacement  Diaphragm  wall  Bracing  Anchors  Residual  soils  Bedrock Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Field measurements of settlement and lateral deformation obtained from three deep excavation sites constructed in mixed ground profiles are presented and analyzed. Settlement measurements were obtained throughout the construction process, categorized in three stages as: (1) preexcavation (i.e., preliminary site work and support wall installation); (2) main excavation and bracing/anchor installation; and (3) postexcavation (i.e., removal of bracing as basement construction proceeds). Maximum preexcavation stage settlements of 0.03%Hw to 0.06%Hw (where Hw = wall or trench depth) were measured at two sites, with the maximum settlements occurring adjacent to the wall during its installation. Maximum ground surface settlements during the main excavation stage ranged from about 0.15%He to 0.30%He (where He = final excavation depth) and the distribution of ground settlement extended to a distance of 1.5He to 2.0He from the wall. Maximum settlements occurred at distances of about 0.3He to 0.5He from the wall at two sites where the wall consisted of concrete cast in situ (concrete diaphragm and concrete secant pile walls), creating a significant reverse curvature in the settlement distribution. The maximum postexcavation stage settlements ranged from 0.07%He to 0.10%He for the three sites, representing roughly 10 to 60% increases in settlement over the main excavation settlements, depending greatly on the specific support removal methods as well as the basement floor construction details employed at an individual site. Lateral deflections during the main excavation stage were consistent with trends reported in the literature, ranging from 0.12%He to 0.23%He, while lateral movement during postexcavation stage ranged from 0.03%He to 0.09%He. Finally, the settlements measured during the main and postexcavation stages are related to the support system stiffness. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i5/p656_s1?isAuthorized=no

Shear band formation observed in ring shear tests on sandy soils / Abouzar Sadrekarimi in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 2 (Fevrier 2010) . - pp. 366-375 Titre : Shear band formation observed in ring shear tests on sandy soils Type de document : texte imprimé Auteurs : Abouzar Sadrekarimi, Auteur ; Scott M. Olson, Auteur Article en page(s) : pp. 366-375 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Ring  shear  test  Shear  banding  Constant  volume  Particle  crushing  Large  shear  displacement  Sand Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Shear band formation is an important factor in understanding failures in soil. In this paper, shear localization and shear band formation and evolution are examined using ring shear tests performed on three sands prepared by air pluviation. A transparent outer confining ring was used to visualize formation and evolution of the entire shear band. By comparing the ring shear stress paths with visual observations made during shearing, the writers show that the specimen shears uniformly over its entire height prior to shear localization. Bifurcation under constant volume and drained conditions occurs as the soil fully mobilizes its effective friction angle, and subsequent shear displacements occur only within the shear band. Consistent with previous studies, the final thickness of the observed shear band ranged from 10 to 14 times the median particle diameter. Substantial particle damage occurred within the shear band after large displacements, particularly for dilative specimens, causing additional strain-softening in contractive specimens and a second phase transformation and considerable strain-softening in dilative specimens. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...] [article] Shear band formation observed in ring shear tests on sandy soils [texte imprimé] / Abouzar Sadrekarimi, Auteur ; Scott M. Olson, Auteur . - pp. 366-375. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 2 (Fevrier 2010) . - pp. 366-375 Mots-clés : Ring  shear  test  Shear  banding  Constant  volume  Particle  crushing  Large  shear  displacement  Sand Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Shear band formation is an important factor in understanding failures in soil. In this paper, shear localization and shear band formation and evolution are examined using ring shear tests performed on three sands prepared by air pluviation. A transparent outer confining ring was used to visualize formation and evolution of the entire shear band. By comparing the ring shear stress paths with visual observations made during shearing, the writers show that the specimen shears uniformly over its entire height prior to shear localization. Bifurcation under constant volume and drained conditions occurs as the soil fully mobilizes its effective friction angle, and subsequent shear displacements occur only within the shear band. Consistent with previous studies, the final thickness of the observed shear band ranged from 10 to 14 times the median particle diameter. Substantial particle damage occurred within the shear band after large displacements, particularly for dilative specimens, causing additional strain-softening in contractive specimens and a second phase transformation and considerable strain-softening in dilative specimens. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...]