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SPT hammer energy ratio versus drop height / T. Leslie Youd in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°3 (Mars 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°3 (Mars 2008) . - pp. 397–400 Titre : SPT hammer energy ratio versus drop height Type de document : texte imprimé Auteurs : T. Leslie Youd, Auteur ; Hannah W. Bartholomew, Auteur Année de publication : 2008 Article en page(s) : pp. 397–400 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Penetration  tests  Energy  Field  tests Résumé : Automatic trip hammers have advantages for standard penetration test (SPT) of consistent drop height and low friction loss during hammer fall. These advantages, however, generate high energy transfer ratios (ER), typically about 90%. This efficiency causes lower sensitivity and higher energy correction coefficients, CE . To reduce ER and CE and to increase the sensitivity of SPT conducted at the Wildlife Liquefaction Array (WLA) and the Garner Valley Downhole Array, instrumented Network for Earthquake Engineering Simulation sites, a 127mm (5.00in.) long sleeve was placed in the hammer mechanism to reduce the drop height from 762mm (30in.) to 635mm (25in.) . To calibrate the energy for these drop heights, measurements were made for a series of SPT tests in Borehole X2 at WLA on November 21, 2003. For these SPT, sleeves were inserted with lengths of 50mm (2in.) , 127mm (5in.) 177mm (7in.) , and no sleeve. Resulting drop heights were 762mm (30in.) , 711mm (28in.) , 635mm (25in.) , and 584mm (23in.) . Results indicate that: (1) ER increases with rod length as expected; (2) corrections for rod length, CR , increased with rod length in accordance with CR published in 2001 by Youd et al.; and (3) for lengths greater than 6m , ER increased approximately linearly with drop height. Average ER30 [ER based on a 762mm (30in.) drop height] were 43% for a 584mm (23in.) drop, 60% for a 635mm (25in.) drop, 84% for 711mm (28in.) drop, and 89% for a 762mm (30in.) drop. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A3%2839 [...] [article] SPT hammer energy ratio versus drop height [texte imprimé] / T. Leslie Youd, Auteur ; Hannah W. Bartholomew, Auteur . - 2008 . - pp. 397–400. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°3 (Mars 2008) . - pp. 397–400 Mots-clés : Penetration  tests  Energy  Field  tests Résumé : Automatic trip hammers have advantages for standard penetration test (SPT) of consistent drop height and low friction loss during hammer fall. These advantages, however, generate high energy transfer ratios (ER), typically about 90%. This efficiency causes lower sensitivity and higher energy correction coefficients, CE . To reduce ER and CE and to increase the sensitivity of SPT conducted at the Wildlife Liquefaction Array (WLA) and the Garner Valley Downhole Array, instrumented Network for Earthquake Engineering Simulation sites, a 127mm (5.00in.) long sleeve was placed in the hammer mechanism to reduce the drop height from 762mm (30in.) to 635mm (25in.) . To calibrate the energy for these drop heights, measurements were made for a series of SPT tests in Borehole X2 at WLA on November 21, 2003. For these SPT, sleeves were inserted with lengths of 50mm (2in.) , 127mm (5in.) 177mm (7in.) , and no sleeve. Resulting drop heights were 762mm (30in.) , 711mm (28in.) , 635mm (25in.) , and 584mm (23in.) . Results indicate that: (1) ER increases with rod length as expected; (2) corrections for rod length, CR , increased with rod length in accordance with CR published in 2001 by Youd et al.; and (3) for lengths greater than 6m , ER increased approximately linearly with drop height. Average ER30 [ER based on a 762mm (30in.) drop height] were 43% for a 584mm (23in.) drop, 60% for a 635mm (25in.) drop, 84% for 711mm (28in.) drop, and 89% for a 762mm (30in.) drop. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A3%2839 [...]

Zero-displacement lateral spreads, 1999 Kocaeli, Turkey, earthquake / T. Leslie Youd 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. 46–61 Titre : Zero-displacement lateral spreads, 1999 Kocaeli, Turkey, earthquake Type de document : texte imprimé Auteurs : T. Leslie Youd, Auteur ; Daniel W. DeDen, Auteur ; Bray, Jonathan D., Auteur Année de publication : 2009 Article en page(s) : pp. 46–61 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Earthquakes  Liquefaction  Displacement  Turkey  Fine-grained  soils  Coarse-grained  soils Résumé : Three potential lateral spreads exhibited negligible displacements during the 1999 Kocaeli, Turkey Earthquake (Mw=7.5) even though they were located within 7km of the fault rupture. These spreads are analyzed to verify and augment current procedures for predicting liquefaction resistance and lateral spread displacement. The sites include Çark Canal and Cumhuriyet Avenue in Adapazari, underlain by fine-grained sediment, and Degirmendere Nose adjacent to Izmit Bay, a steeply sloping area underlain by moderately dense silty sand. The plasticity index and moisture content criteria of Bray and Sancio set forth in 2006 indicate that much of the fine-grained sediment is liquefiable. Even though liquefaction likely occurred, lateral spreading did not occur due either to the dilative nature of fine-grained, sandlike sediments or the inherent strength of claylike sediments. Corrected blow counts, (N1)60 , in moderately dense sand at Degirmendere Nose range from 15 to 25 blows/ 30cm , indicating that liquefaction should have occurred but that the silty sand was too dense and dilative to deform. This finding is consistent with the MLR procedure of Youd et al. set forth in 2002 that identifies liquefiable sands with (N1)60 greater than 15 blows/ 30cm as resistant to lateral spread during earthquakes with M<8 . En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A1%2846 [...] [article] Zero-displacement lateral spreads, 1999 Kocaeli, Turkey, earthquake [texte imprimé] / T. Leslie Youd, Auteur ; Daniel W. DeDen, Auteur ; Bray, Jonathan D., Auteur . - 2009 . - pp. 46–61. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°1 (Janvier 2009) . - pp. 46–61 Mots-clés : Earthquakes  Liquefaction  Displacement  Turkey  Fine-grained  soils  Coarse-grained  soils Résumé : Three potential lateral spreads exhibited negligible displacements during the 1999 Kocaeli, Turkey Earthquake (Mw=7.5) even though they were located within 7km of the fault rupture. These spreads are analyzed to verify and augment current procedures for predicting liquefaction resistance and lateral spread displacement. The sites include Çark Canal and Cumhuriyet Avenue in Adapazari, underlain by fine-grained sediment, and Degirmendere Nose adjacent to Izmit Bay, a steeply sloping area underlain by moderately dense silty sand. The plasticity index and moisture content criteria of Bray and Sancio set forth in 2006 indicate that much of the fine-grained sediment is liquefiable. Even though liquefaction likely occurred, lateral spreading did not occur due either to the dilative nature of fine-grained, sandlike sediments or the inherent strength of claylike sediments. Corrected blow counts, (N1)60 , in moderately dense sand at Degirmendere Nose range from 15 to 25 blows/ 30cm , indicating that liquefaction should have occurred but that the silty sand was too dense and dilative to deform. This finding is consistent with the MLR procedure of Youd et al. set forth in 2002 that identifies liquefiable sands with (N1)60 greater than 15 blows/ 30cm as resistant to lateral spread during earthquakes with M<8 . En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A1%2846 [...]