Documents disponibles écrits par cet auteur

Analysis of factors influencing soil classification using normalized piezocone tip resistance and pore pressure parameters / James A. Schneider in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°11 (Novembre 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°11 (Novembre 2008) . - pp. 1569–1586 Titre : Analysis of factors influencing soil classification using normalized piezocone tip resistance and pore pressure parameters Type de document : texte imprimé Auteurs : James A. Schneider, Auteur ; Mark F. Randolph, Auteur ; Paul W. Mayne, Auteur Année de publication : 2009 Article en page(s) : pp. 1569–1586 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil  classification  Cone  penetration  tests  Silts  Clays  Overconsolidated  soils Résumé : This paper discusses the development of a framework for classifying soil using normalized piezocone test (CPTU) data from the corrected tip resistance (qt) and penetration pore-water pressure at the shoulder (u2) . Parametric studies for normalized cone tip resistance (Q=qcnet/σ′v0) and normalized excess pressures (Δu2/σ′v0) as a function of overconsolidation ratio (OCR=σ′vy/σ′v0) during undrained penetration are combined with piezocone data from clay sites, as well as results from relatively uniform thick deposits of sands, silts, and varietal clays from around the globe. The study focuses on separating the influence of yield stress ratio from that of partial consolidation on normalized CPTU parameters, which both tend to increase Q and decrease the pore pressure parameter (Bq=Δu2/qcnet) . The resulting recommended classification chart is significantly different from existing charts, and implies that assessment of data in Q–Δu2/σ′v0 space is superior to Q–Bq space when evaluating piezocone data for a range of soil types. Still, there are zones of overlap for silty soils and heavily overconsolidated clays, thus requiring that supplementary information to Q and Δu2/σ′v0 be obtained in unfamiliar geologies, including variable rate penetration tests, dissipation tests, CPT friction ratio, or soil sampling. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A11%281 [...] [article] Analysis of factors influencing soil classification using normalized piezocone tip resistance and pore pressure parameters [texte imprimé] / James A. Schneider, Auteur ; Mark F. Randolph, Auteur ; Paul W. Mayne, Auteur . - 2009 . - pp. 1569–1586. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°11 (Novembre 2008) . - pp. 1569–1586 Mots-clés : Soil  classification  Cone  penetration  tests  Silts  Clays  Overconsolidated  soils Résumé : This paper discusses the development of a framework for classifying soil using normalized piezocone test (CPTU) data from the corrected tip resistance (qt) and penetration pore-water pressure at the shoulder (u2) . Parametric studies for normalized cone tip resistance (Q=qcnet/σ′v0) and normalized excess pressures (Δu2/σ′v0) as a function of overconsolidation ratio (OCR=σ′vy/σ′v0) during undrained penetration are combined with piezocone data from clay sites, as well as results from relatively uniform thick deposits of sands, silts, and varietal clays from around the globe. The study focuses on separating the influence of yield stress ratio from that of partial consolidation on normalized CPTU parameters, which both tend to increase Q and decrease the pore pressure parameter (Bq=Δu2/qcnet) . The resulting recommended classification chart is significantly different from existing charts, and implies that assessment of data in Q–Δu2/σ′v0 space is superior to Q–Bq space when evaluating piezocone data for a range of soil types. Still, there are zones of overlap for silty soils and heavily overconsolidated clays, thus requiring that supplementary information to Q and Δu2/σ′v0 be obtained in unfamiliar geologies, including variable rate penetration tests, dissipation tests, CPT friction ratio, or soil sampling. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A11%281 [...]

Database assessment of CPT-based design methods for axial capacity of driven piles in siliceous sands / James A. Schneider in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°9 (Septembre 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°9 (Septembre 2008) . - pp. 1227–1244 Titre : Database assessment of CPT-based design methods for axial capacity of driven piles in siliceous sands Type de document : texte imprimé Auteurs : James A. Schneider, Auteur Année de publication : 2008 Article en page(s) : pp. 1227–1244 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Driven  piles  Cone  penetration  tests  Foundation  design  Compression  Sand  Pile  load  tests  Databases Résumé : Numerous cone penetration test (CPT)-based methods exist for calculation of the axial pile capacity in sands, but no clear guidance is presently available to assist designers in the selection of the most appropriate method. To assist in this regard, this paper examines the predictive performance of a range of pile design methods against a newly compiled database of static load tests on driven piles in siliceous sands with adjacent CPT profiles. Seven driven pile design methods are considered, including the conventional American Petroleum Institute (API) approach, simplified CPT alpha methods, and four new CPT-based methods, which are now presented in the commentary of the 22nd edition of the API recommendations. Mean and standard deviation database statistics for the design methods are presented for the entire 77 pile database, as well as for smaller subset databases separated by pile material (steel and concrete), end condition (open versus closed), and direction of loading (tension versus compression). Certain methods are seen to exhibit bias toward length, relative density, cone tip resistance, and pile end condition. Other methods do not exhibit any apparent bias (even though their formulations differ significantly) due to the limited size of the database subsets and the large number of factors known to influence pile capacity in sand. The database statistics for the best performing methods are substantially better than those for the API approach and the simplified alpha methods. Improved predictive reliability will emerge with an extension of the database and the inclusion of additional important controlling factors affecting capacity. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2812 [...] [article] Database assessment of CPT-based design methods for axial capacity of driven piles in siliceous sands [texte imprimé] / James A. Schneider, Auteur . - 2008 . - pp. 1227–1244. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°9 (Septembre 2008) . - pp. 1227–1244 Mots-clés : Driven  piles  Cone  penetration  tests  Foundation  design  Compression  Sand  Pile  load  tests  Databases Résumé : Numerous cone penetration test (CPT)-based methods exist for calculation of the axial pile capacity in sands, but no clear guidance is presently available to assist designers in the selection of the most appropriate method. To assist in this regard, this paper examines the predictive performance of a range of pile design methods against a newly compiled database of static load tests on driven piles in siliceous sands with adjacent CPT profiles. Seven driven pile design methods are considered, including the conventional American Petroleum Institute (API) approach, simplified CPT alpha methods, and four new CPT-based methods, which are now presented in the commentary of the 22nd edition of the API recommendations. Mean and standard deviation database statistics for the design methods are presented for the entire 77 pile database, as well as for smaller subset databases separated by pile material (steel and concrete), end condition (open versus closed), and direction of loading (tension versus compression). Certain methods are seen to exhibit bias toward length, relative density, cone tip resistance, and pile end condition. Other methods do not exhibit any apparent bias (even though their formulations differ significantly) due to the limited size of the database subsets and the large number of factors known to influence pile capacity in sand. The database statistics for the best performing methods are substantially better than those for the API approach and the simplified alpha methods. Improved predictive reliability will emerge with an extension of the database and the inclusion of additional important controlling factors affecting capacity. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2812 [...]

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