Documents disponibles écrits par cet auteur

Shaft capacity of displacement piles in clay using the cone penetration test / Barry M. Lehane in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 253-266 Titre : Shaft capacity of displacement piles in clay using the cone penetration test Type de document : texte imprimé Auteurs : Barry M. Lehane, Auteur ; Yunong Li, Auteur ; Ryan Williams, Auteur Année de publication : 2013 Article en page(s) : pp. 253-266 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : shafts;  friction;  displacement;  piles;  clays Résumé : The prediction of the shaft capacity of displacement piles in clay still relies wholly on empirical or semiempirical approaches. This paper examines the predictive abilities of five well-known methods against an extended version of an existing database of pile tests. It is seen that coefficients of variation (COVs) of the ratio of calculated to measured capacities (Qc/Qm) are significantly higher than expected. The paper then uses the database of shaft capacities to examine potential relationships between local shaft friction and the cone penetration test end resistance (qt). Predictions are subsequently compared with capacities measured in a series of centrifuge tests and with the distributions of peak frictions observed in two well-documented field tests. Widely different formulations adopted by each of the existing empirical methods give broadly similar COV values for Qc/Qm ratios, and it is concluded that the database of high-quality pile tests needs to be expanded significantly if the reliability of estimates of shaft capacity in clay is to be improved. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000749 [article] Shaft capacity of displacement piles in clay using the cone penetration test [texte imprimé] / Barry M. Lehane, Auteur ; Yunong Li, Auteur ; Ryan Williams, Auteur . - 2013 . - pp. 253-266. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 253-266 Mots-clés : shafts;  friction;  displacement;  piles;  clays Résumé : The prediction of the shaft capacity of displacement piles in clay still relies wholly on empirical or semiempirical approaches. This paper examines the predictive abilities of five well-known methods against an extended version of an existing database of pile tests. It is seen that coefficients of variation (COVs) of the ratio of calculated to measured capacities (Qc/Qm) are significantly higher than expected. The paper then uses the database of shaft capacities to examine potential relationships between local shaft friction and the cone penetration test end resistance (qt). Predictions are subsequently compared with capacities measured in a series of centrifuge tests and with the distributions of peak frictions observed in two well-documented field tests. Widely different formulations adopted by each of the existing empirical methods give broadly similar COV values for Qc/Qm ratios, and it is concluded that the database of high-quality pile tests needs to be expanded significantly if the reliability of estimates of shaft capacity in clay is to be improved. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000749

Shaft friction from instrumented displacement piles in an uncemented calcareous sand / Barry M. Lehane in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 11 (Novembre 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 11 (Novembre 2012) . - pp. 1357-1368 Titre : Shaft friction from instrumented displacement piles in an uncemented calcareous sand Type de document : texte imprimé Auteurs : Barry M. Lehane, Auteur ; James A. Schneider, Auteur ; Jit Kheng Lim, Auteur Année de publication : 2013 Article en page(s) : pp. 1357-1368 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Calcareous  sand  pile  cyclic Résumé : The behavior of displacement piles in uncemented calcareous sand is investigated using field piles instrumented with a sensor that simultaneously records the radial stress and shear stress at specific locations on the pile shafts. These tests are interpreted with the assistance of data from adjacent self-boring pressuremeter tests and from monotonic and cyclic direct shear interface tests performed on reconstituted samples. The existence of extremely low radial stresses on the pile shafts is verified. Although dilation during shear is seen to compensate for such low radial stresses, short-term shaft capacities are much lower than capacities of equivalent piles in siliceous sands. The development of a bonded or welded crust to the pile shaft was seen to be the primary contributor to the setup observed at the test site; this crust forced failure to take place at a sand-sand rather than a sand-steel interface and also gave rise to higher levels of dilation during monotonic loading. The welded sand crust did not, however, give rise to a higher long-term cyclic capacity. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000712 [article] Shaft friction from instrumented displacement piles in an uncemented calcareous sand [texte imprimé] / Barry M. Lehane, Auteur ; James A. Schneider, Auteur ; Jit Kheng Lim, Auteur . - 2013 . - pp. 1357-1368. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 11 (Novembre 2012) . - pp. 1357-1368 Mots-clés : Calcareous  sand  pile  cyclic Résumé : The behavior of displacement piles in uncemented calcareous sand is investigated using field piles instrumented with a sensor that simultaneously records the radial stress and shear stress at specific locations on the pile shafts. These tests are interpreted with the assistance of data from adjacent self-boring pressuremeter tests and from monotonic and cyclic direct shear interface tests performed on reconstituted samples. The existence of extremely low radial stresses on the pile shafts is verified. Although dilation during shear is seen to compensate for such low radial stresses, short-term shaft capacities are much lower than capacities of equivalent piles in siliceous sands. The development of a bonded or welded crust to the pile shaft was seen to be the primary contributor to the setup observed at the test site; this crust forced failure to take place at a sand-sand rather than a sand-steel interface and also gave rise to higher levels of dilation during monotonic loading. The welded sand crust did not, however, give rise to a higher long-term cyclic capacity. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000712