Documents disponibles écrits par cet auteur

Centrifuge modeling for liquefaction mitigation using colloidal silica stabilizer / Carolyn T. Conlee 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. 1334-1345 Titre : Centrifuge modeling for liquefaction mitigation using colloidal silica stabilizer Type de document : texte imprimé Auteurs : Carolyn T. Conlee, Auteur ; Patricia M. Gallagher, Auteur ; Ross W. Boulanger, Auteur Année de publication : 2013 Article en page(s) : pp. 1334-1345 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Colloidal  silica  Liquefaction  Centrifuge  testing  Shear  strain Résumé : This paper reports the results of two centrifuge tests that were conducted to evaluate the effectiveness of colloidal silica for liquefaction mitigation. Colloidal silica has been selected as a stabilizer material in soils because of its permanence and ability to increase the strength of soils over time. The centrifuge model geometry was selected to study the effects of lateral spreading in a 4.8-m-thick liquefiable layer overlain by a silty clay sloping toward a central channel. The centrifuge test evaluates the response of untreated loose sands versus loose sands treated with 9, 5, and 4% colloidal silica concentrations (by weight). The models were subjected to a series of peak horizontal base accelerations ranging from 0.007 up to 1.3g (prototype) with a testing centrifugal acceleration of 15g. The results show a reduction in both lateral spreading and settlement in colloidal silica–treated sands versus untreated sands. The shear modulus at low strains was determined from shear wave velocity measurements for the untreated and treated loose sands. The hysteretic response during cyclic loading was also determined for various levels of shaking. The results from the centrifuge tests show an increase in cyclic resistance ratios and a decrease in cyclic shear strains for increasing colloidal silica concentrations. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000703 [article] Centrifuge modeling for liquefaction mitigation using colloidal silica stabilizer [texte imprimé] / Carolyn T. Conlee, Auteur ; Patricia M. Gallagher, Auteur ; Ross W. Boulanger, Auteur . - 2013 . - pp. 1334-1345. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 11 (Novembre 2012) . - pp. 1334-1345 Mots-clés : Colloidal  silica  Liquefaction  Centrifuge  testing  Shear  strain Résumé : This paper reports the results of two centrifuge tests that were conducted to evaluate the effectiveness of colloidal silica for liquefaction mitigation. Colloidal silica has been selected as a stabilizer material in soils because of its permanence and ability to increase the strength of soils over time. The centrifuge model geometry was selected to study the effects of lateral spreading in a 4.8-m-thick liquefiable layer overlain by a silty clay sloping toward a central channel. The centrifuge test evaluates the response of untreated loose sands versus loose sands treated with 9, 5, and 4% colloidal silica concentrations (by weight). The models were subjected to a series of peak horizontal base accelerations ranging from 0.007 up to 1.3g (prototype) with a testing centrifugal acceleration of 15g. The results show a reduction in both lateral spreading and settlement in colloidal silica–treated sands versus untreated sands. The shear modulus at low strains was determined from shear wave velocity measurements for the untreated and treated loose sands. The hysteretic response during cyclic loading was also determined for various levels of shaking. The results from the centrifuge tests show an increase in cyclic resistance ratios and a decrease in cyclic shear strains for increasing colloidal silica concentrations. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000703

Colloidal silica transport through liquefiable porous media / Patricia M. Gallagher 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. 1702–1712 Titre : Colloidal silica transport through liquefiable porous media Type de document : texte imprimé Auteurs : Patricia M. Gallagher, Auteur ; Yuanzhi Lin, Auteur Année de publication : 2009 Article en page(s) : pp. 1702–1712 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : ColloidsSilicaSoil  liquefactionGroutingSoil  stabilizationPorous  media Résumé : Mitigation of liquefaction potential in loose granular soil can theoretically be achieved through permeation and subsequent gelation of dilute colloidal silica stabilizer. However, practical application of this technique requires efficient and adequate delivery of the stabilizer to the liquefiable soil prior to gelation. The purpose of this research was to evaluate colloidal silica transport mechanisms and to determine if an adequate concentration can be delivered to a soil column prior to gelation. The laboratory work consisted of grouting 15 short (0.9 m) columns tests packed with Nevada No. 120, Ottawa 20/30, or graded silty sand to identify the variables that influence stabilizer transport through porous media. It was found that colloidal silica can be successfully delivered through 0.9-m columns packed with loose sand efficiently and in an adequate concentration to mitigate the liquefaction potential. Transport occurs primarily by advection with limited hydrodynamic dispersion, so Darcy’s law can be used to predict flow. The Kozeny-Carmen equation can be used to include the effect of increasing viscosity on transport by incorporating the power law mixing rule of Todd. The primary variables influencing stabilizer transport were found to be the viscosity of the colloidal silica stabilizer, the hydraulic gradient, and the hydraulic conductivity of the liquefiable soil. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000123 [article] Colloidal silica transport through liquefiable porous media [texte imprimé] / Patricia M. Gallagher, Auteur ; Yuanzhi Lin, Auteur . - 2009 . - pp. 1702–1712. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 11 (Novembre 2009) . - pp. 1702–1712 Mots-clés : ColloidsSilicaSoil  liquefactionGroutingSoil  stabilizationPorous  media Résumé : Mitigation of liquefaction potential in loose granular soil can theoretically be achieved through permeation and subsequent gelation of dilute colloidal silica stabilizer. However, practical application of this technique requires efficient and adequate delivery of the stabilizer to the liquefiable soil prior to gelation. The purpose of this research was to evaluate colloidal silica transport mechanisms and to determine if an adequate concentration can be delivered to a soil column prior to gelation. The laboratory work consisted of grouting 15 short (0.9 m) columns tests packed with Nevada No. 120, Ottawa 20/30, or graded silty sand to identify the variables that influence stabilizer transport through porous media. It was found that colloidal silica can be successfully delivered through 0.9-m columns packed with loose sand efficiently and in an adequate concentration to mitigate the liquefaction potential. Transport occurs primarily by advection with limited hydrodynamic dispersion, so Darcy’s law can be used to predict flow. The Kozeny-Carmen equation can be used to include the effect of increasing viscosity on transport by incorporating the power law mixing rule of Todd. The primary variables influencing stabilizer transport were found to be the viscosity of the colloidal silica stabilizer, the hydraulic gradient, and the hydraulic conductivity of the liquefiable soil. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000123

Dynamic response of compacted CG, DM, and CG-DM blends / Patricia M. Gallagher in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 8 (Août 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 8 (Août 2009) . - pp. 1148–1154 Titre : Dynamic response of compacted CG, DM, and CG-DM blends Type de document : texte imprimé Auteurs : Patricia M. Gallagher, Auteur ; Murat Hamderi, Auteur ; Dennis G. Grubb, Auteur Année de publication : 2009 Article en page(s) : pp. 1148–1154 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Cyclic  tests  Dynamic  response  Recycling  Glass  Dredge  spoil  Physical  properties  Soil  mixing Résumé : The cyclic behavior of 9.5 mm (3/8 in.) minus curbside-collected crushed glass (CG) blended with dredged material (DM), classified as an organic silt by the Unified Soil Classification System, was evaluated using a cyclic triaxial testing program. Tests were performed on 100% CG and 100% DM specimens, and 20/80, 40/60, 60/40, and 80/20 CG-DM blends (dry CG content is reported first). The specimens were compacted to a dry unit weight equivalent to 95% of the maximum dry density based on ASTM D1557. For each material, a minimum of three specimens was tested at cyclic stress ratios of 0.20, 0.35, and 0.45. The DM used in this study exhibited significant plasticity, which would be expected to display cyclic softening behavior according to liquefaction susceptibility criteria proposed by Boulanger and Idriss in 2006. However, the high density of the material resulted in transitional behavior between cyclic mobility and cyclic softening. These findings suggest that as long as the CG, DM, and CG-DM blends are compacted, they should not be susceptible to strength loss or large strain under cyclic loading. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000005 [article] Dynamic response of compacted CG, DM, and CG-DM blends [texte imprimé] / Patricia M. Gallagher, Auteur ; Murat Hamderi, Auteur ; Dennis G. Grubb, Auteur . - 2009 . - pp. 1148–1154. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 8 (Août 2009) . - pp. 1148–1154 Mots-clés : Cyclic  tests  Dynamic  response  Recycling  Glass  Dredge  spoil  Physical  properties  Soil  mixing Résumé : The cyclic behavior of 9.5 mm (3/8 in.) minus curbside-collected crushed glass (CG) blended with dredged material (DM), classified as an organic silt by the Unified Soil Classification System, was evaluated using a cyclic triaxial testing program. Tests were performed on 100% CG and 100% DM specimens, and 20/80, 40/60, 60/40, and 80/20 CG-DM blends (dry CG content is reported first). The specimens were compacted to a dry unit weight equivalent to 95% of the maximum dry density based on ASTM D1557. For each material, a minimum of three specimens was tested at cyclic stress ratios of 0.20, 0.35, and 0.45. The DM used in this study exhibited significant plasticity, which would be expected to display cyclic softening behavior according to liquefaction susceptibility criteria proposed by Boulanger and Idriss in 2006. However, the high density of the material resulted in transitional behavior between cyclic mobility and cyclic softening. These findings suggest that as long as the CG, DM, and CG-DM blends are compacted, they should not be susceptible to strength loss or large strain under cyclic loading. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000005