Documents disponibles écrits par cet auteur

Cyclic and rapid axial load tests on displacement piles in soft clay / Paul Doherty in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 8 (Août 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 8 (Août 2012) . - pp. 1022–1026 Titre : Cyclic and rapid axial load tests on displacement piles in soft clay Type de document : texte imprimé Auteurs : Paul Doherty, Auteur ; Kenneth Gavin, Auteur Année de publication : 2012 Article en page(s) : pp. 1022–1026 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Foundations  Piles  Testing  Cyclic  loading  Offshore  loading  Pore  pressure Résumé : Offshore piles are subjected to complex loading regimes that include both rapidly applied static and cyclic loads. This paper describes an experimental investigation conducted to assess the factors influencing the response of offshore piles to these loading conditions. The tests were performed using instrumented model piles installed in soft clay. During cyclic loading, the piles demonstrated a transition from stable to unstable behavior when the applied loads reached a specific load threshold. Stable behavior was defined when increments of plastic displacement decreased as the number of load cycles increased. During stable behavior, radial effective stresses at the pile-soil interface remained constant. During unstable behavior, pore pressures at the pile-soil interface rose as the number of cycles increased. This resulted in reduced radial effective stresses and progressively increasing displacement rates. Because of the presence of these excess pore pressures, the shaft resistance recorded during static load tests, performed after unstable cyclic loading, were lower than those measured on piles where the pore pressure was fully equalized. However, the axial resistance was seen to be rate dependent. Fast loading of the pile resulted in reductions of pore water pressure at the soil-pile interface and enhanced shaft resistance, which might overcome the negative effect caused by cyclic loading. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000655 [article] Cyclic and rapid axial load tests on displacement piles in soft clay [texte imprimé] / Paul Doherty, Auteur ; Kenneth Gavin, Auteur . - 2012 . - pp. 1022–1026. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 8 (Août 2012) . - pp. 1022–1026 Mots-clés : Foundations  Piles  Testing  Cyclic  loading  Offshore  loading  Pore  pressure Résumé : Offshore piles are subjected to complex loading regimes that include both rapidly applied static and cyclic loads. This paper describes an experimental investigation conducted to assess the factors influencing the response of offshore piles to these loading conditions. The tests were performed using instrumented model piles installed in soft clay. During cyclic loading, the piles demonstrated a transition from stable to unstable behavior when the applied loads reached a specific load threshold. Stable behavior was defined when increments of plastic displacement decreased as the number of load cycles increased. During stable behavior, radial effective stresses at the pile-soil interface remained constant. During unstable behavior, pore pressures at the pile-soil interface rose as the number of cycles increased. This resulted in reduced radial effective stresses and progressively increasing displacement rates. Because of the presence of these excess pore pressures, the shaft resistance recorded during static load tests, performed after unstable cyclic loading, were lower than those measured on piles where the pore pressure was fully equalized. However, the axial resistance was seen to be rate dependent. Fast loading of the pile resulted in reductions of pore water pressure at the soil-pile interface and enhanced shaft resistance, which might overcome the negative effect caused by cyclic loading. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000655

Shaft capacity of open-ended piles in clay / Paul Doherty in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 11 (Novembre 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 11 (Novembre 2011) . - pp. 1090-1102 Titre : Shaft capacity of open-ended piles in clay Type de document : texte imprimé Auteurs : Paul Doherty, Auteur ; Kenneth Gavin, Auteur Année de publication : 2012 Article en page(s) : pp. 1090-1102 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Foundations  Piles  Open-ended  penetration  Radial  stresses  Instrumentation Résumé : This paper describes an experimental investigation designed to assess the impact of pile end condition on the capacity of piles installed in soft clay. A series of field tests are described in which instrumented open-ended and closed-ended model piles were jacked into soft clay. The radial stresses, pore pressures, and load distribution were recorded throughout installation, equalization, and load-testing. Although the total stress and pore pressure developed during installation were related to the degree of soil plugging, the radial effective stress that controls the shaft resistance was shown to be independent of the mode of penetration. The long-term shaft capacity of the open-ended pile was closely comparable to that developed by closed-ended piles, suggesting a limited influence of end condition on the fully equalized shaft resistance. In contrast to the shaft resistance, the base capacity was highly dependent on the degree of plugging. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i11/p1090_s1?isAuthorized=no [article] Shaft capacity of open-ended piles in clay [texte imprimé] / Paul Doherty, Auteur ; Kenneth Gavin, Auteur . - 2012 . - pp. 1090-1102. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 11 (Novembre 2011) . - pp. 1090-1102 Mots-clés : Foundations  Piles  Open-ended  penetration  Radial  stresses  Instrumentation Résumé : This paper describes an experimental investigation designed to assess the impact of pile end condition on the capacity of piles installed in soft clay. A series of field tests are described in which instrumented open-ended and closed-ended model piles were jacked into soft clay. The radial stresses, pore pressures, and load distribution were recorded throughout installation, equalization, and load-testing. Although the total stress and pore pressure developed during installation were related to the degree of soil plugging, the radial effective stress that controls the shaft resistance was shown to be independent of the mode of penetration. The long-term shaft capacity of the open-ended pile was closely comparable to that developed by closed-ended piles, suggesting a limited influence of end condition on the fully equalized shaft resistance. In contrast to the shaft resistance, the base capacity was highly dependent on the degree of plugging. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i11/p1090_s1?isAuthorized=no