Documents disponibles écrits par cet auteur

Influence of partial consolidation during cone penetration on estimated soil behavior type and pore pressure dissipation measurements / Jason T. DeJong in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 7 (Juillet 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 7 (Juillet 2012) . - pp. 777–788 Titre : Influence of partial consolidation during cone penetration on estimated soil behavior type and pore pressure dissipation measurements Type de document : texte imprimé Auteurs : Jason T. DeJong, Auteur ; Mark Randolph, Auteur Année de publication : 2012 Article en page(s) : pp. 777–788 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Cone  penetration  test  CPT  Cone  penetrometer  Penetration  rate  Consolidation  Dissipation  test  Soil  behavior  type  Coefficient  of  consolidation  Intermediate  soils Résumé : Estimation of soil behavior type from cone penetration testing, and the interpretation of dissipation tests, is complicated in intermediate soil types, such as silty sands, sandy silts, etc., where partial consolidation occurs during penetration. This issue is investigated in this paper using results from cavity expansion and finite element analyses as well as field and centrifuge piezocone data. The implications for soil classification are examined using analytical expressions to explore the effect of normalized shear strength, rigidity index, and overconsolidation ratio relative to the influence of partial consolidation and viscous effects under fully undrained conditions. It is shown that partial drainage conditions can affect where data plots on soil behavior charts, thus complicating soil classification. The effect on dissipation tests following partial consolidation during cone penetration is shown to create errors in interpretation using experimental and numerical data. A new approach is developed based in part on manipulation of solutions for pore pressure dissipation (following undrained penetration) to account for these errors when interpreting dissipation tests. Errors can become significant during standard cone penetration testing when the t50 dissipation time is less than about 50 s. Guidelines, including equations and a chart, are presented for practical use. Finally, implementation of this approach is demonstrated in a brief case study. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000646 [article] Influence of partial consolidation during cone penetration on estimated soil behavior type and pore pressure dissipation measurements [texte imprimé] / Jason T. DeJong, Auteur ; Mark Randolph, Auteur . - 2012 . - pp. 777–788. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 7 (Juillet 2012) . - pp. 777–788 Mots-clés : Cone  penetration  test  CPT  Cone  penetrometer  Penetration  rate  Consolidation  Dissipation  test  Soil  behavior  type  Coefficient  of  consolidation  Intermediate  soils Résumé : Estimation of soil behavior type from cone penetration testing, and the interpretation of dissipation tests, is complicated in intermediate soil types, such as silty sands, sandy silts, etc., where partial consolidation occurs during penetration. This issue is investigated in this paper using results from cavity expansion and finite element analyses as well as field and centrifuge piezocone data. The implications for soil classification are examined using analytical expressions to explore the effect of normalized shear strength, rigidity index, and overconsolidation ratio relative to the influence of partial consolidation and viscous effects under fully undrained conditions. It is shown that partial drainage conditions can affect where data plots on soil behavior charts, thus complicating soil classification. The effect on dissipation tests following partial consolidation during cone penetration is shown to create errors in interpretation using experimental and numerical data. A new approach is developed based in part on manipulation of solutions for pore pressure dissipation (following undrained penetration) to account for these errors when interpreting dissipation tests. Errors can become significant during standard cone penetration testing when the t50 dissipation time is less than about 50 s. Guidelines, including equations and a chart, are presented for practical use. Finally, implementation of this approach is demonstrated in a brief case study. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000646

Influence of particle properties and initial specimen state on one-dimensional compression and hydraulic conductivity / Jason T. DeJong in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N°3 (Mars 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°3 (Mars 2009) . - pp. 449–454 Titre : Influence of particle properties and initial specimen state on one-dimensional compression and hydraulic conductivity Type de document : texte imprimé Auteurs : Jason T. DeJong, Auteur ; G. Geoffrey Christoph, Auteur Année de publication : 2009 Article en page(s) : pp. 449–454 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Crushing  Hydraulic  conductivity  Compression  Sand  Particles Résumé : Particle crushing can adversely affect geotechnical system performance; examples include clogging in wells, pile shaft capacity degradation, and postconstruction settlements. The generation of fines results in volumetric compression and a reduction hydraulic conductivity, which is important for geotechnical systems whose performance is directly dependent on pore pressure dissipation, groundwater flow, or hydraulic pumping. Knowledge of hydraulic conductivity change is poorly understood due to limited experimental data, and an ability to predict this change is lacking. The role of single particle properties, initial specimen state conditions, and loading conditions on the evolution of hydraulic conductivity with particle crushing was examined experimentally. Specimen response exhibited an overshoot behavior and the convergence to a unique condition independent of initial relative density, gradation, and particle shape. The hydraulic conductivity decreased by 2–3 times before specimen yield, and by 2–3 orders of magnitude after specimen yield. Empirical correlations were developed to estimate the change in hydraulic conductivity given the initial permeability and select crushing parameter values at the stress level of interest. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A3%2844 [...] [article] Influence of particle properties and initial specimen state on one-dimensional compression and hydraulic conductivity [texte imprimé] / Jason T. DeJong, Auteur ; G. Geoffrey Christoph, Auteur . - 2009 . - pp. 449–454. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°3 (Mars 2009) . - pp. 449–454 Mots-clés : Crushing  Hydraulic  conductivity  Compression  Sand  Particles Résumé : Particle crushing can adversely affect geotechnical system performance; examples include clogging in wells, pile shaft capacity degradation, and postconstruction settlements. The generation of fines results in volumetric compression and a reduction hydraulic conductivity, which is important for geotechnical systems whose performance is directly dependent on pore pressure dissipation, groundwater flow, or hydraulic pumping. Knowledge of hydraulic conductivity change is poorly understood due to limited experimental data, and an ability to predict this change is lacking. The role of single particle properties, initial specimen state conditions, and loading conditions on the evolution of hydraulic conductivity with particle crushing was examined experimentally. Specimen response exhibited an overshoot behavior and the convergence to a unique condition independent of initial relative density, gradation, and particle shape. The hydraulic conductivity decreased by 2–3 times before specimen yield, and by 2–3 orders of magnitude after specimen yield. Empirical correlations were developed to estimate the change in hydraulic conductivity given the initial permeability and select crushing parameter values at the stress level of interest. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A3%2844 [...]

Role of initial state, material properties, and confinement condition on local and global soil-structure interface behavior / Jason T. DeJong in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 11 (Novembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 11 (Novembre 2009) . - pp. 1646–1660 Titre : Role of initial state, material properties, and confinement condition on local and global soil-structure interface behavior Type de document : texte imprimé Auteurs : Jason T. DeJong, Auteur ; Zachary J. Westgate, Auteur Année de publication : 2009 Article en page(s) : pp. 1646–1660 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil-structure  interactionsLocalizationMaterial  propertiesConfinement Résumé : Difficulty in predicting the transfer of load from a structural element to the surrounding soil has limited the reliability of geotechnical design and performance. The remaining uncertainty in load transfer mechanics is primarily due to the localized nature of the mechanism. This study examines localized soil-structure interaction through a series of monotonic direct interface shear tests. Parameters investigated include relative density, particle angularity, particle hardness, surface roughness, normal stress, and normal stiffness. The soil-structure interface behavior is quantified in terms of the local two-dimensional displacement and strain distributions within the test specimens using particle image velocimetry. In addition, the localized zone of soil adjacent to the structural surface within which shear and volumetric strains occur is quantified. The relative density of the soil, and the relationship between particle characteristics (angularity and hardness) and surface roughness are shown to have the greatest effect on local interface behavior, followed by confining stress and stiffness conditions. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A11%281 [...] [article] Role of initial state, material properties, and confinement condition on local and global soil-structure interface behavior [texte imprimé] / Jason T. DeJong, Auteur ; Zachary J. Westgate, Auteur . - 2009 . - pp. 1646–1660. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 11 (Novembre 2009) . - pp. 1646–1660 Mots-clés : Soil-structure  interactionsLocalizationMaterial  propertiesConfinement Résumé : Difficulty in predicting the transfer of load from a structural element to the surrounding soil has limited the reliability of geotechnical design and performance. The remaining uncertainty in load transfer mechanics is primarily due to the localized nature of the mechanism. This study examines localized soil-structure interaction through a series of monotonic direct interface shear tests. Parameters investigated include relative density, particle angularity, particle hardness, surface roughness, normal stress, and normal stiffness. The soil-structure interface behavior is quantified in terms of the local two-dimensional displacement and strain distributions within the test specimens using particle image velocimetry. In addition, the localized zone of soil adjacent to the structural surface within which shear and volumetric strains occur is quantified. The relative density of the soil, and the relationship between particle characteristics (angularity and hardness) and surface roughness are shown to have the greatest effect on local interface behavior, followed by confining stress and stiffness conditions. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A11%281 [...]