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

Cyclic softening of low-plasticity clay and its effect on seismic foundation performance / Daniel B. Chu 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. 1595–1608 Titre : Cyclic softening of low-plasticity clay and its effect on seismic foundation performance Type de document : texte imprimé Auteurs : Daniel B. Chu, Auteur ; Stewart, Jonathan P., Auteur ; Ross W. Boulanger, Auteur Année de publication : 2009 Article en page(s) : pp. 1595–1608 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil  liquefaction  Seismic  effects  Soil  structure  interaction  Shallow  foundations  In  situ  tests  Taiwan  Earthquakes Résumé : During the 1999 Chi-Chi Earthquake (Mw=7.6) , significant incidents of ground failure occurred in Wufeng, Taiwan, which experienced peak accelerations ∼0.7g . This paper describes the results of field investigations and analyses of a small region within Wufeng along an E–W trending line 350m long. The east end of the line has single-story structures for which there was no evidence of ground failure. The west end of the line had three to six-story reinforced concrete structures that underwent differential settlement and foundation bearing failures. No ground failure was observed in the free field. Surficial soils consist of low-plasticity silty clays that extend to 8–12m depth in the damaged area (west side), and 3–10m depth in the undamaged area (east side). A significant fraction of the foundation soils at the site are liquefaction susceptible based on several recently proposed criteria, but the site performance cannot be explained by analysis in existing liquefaction frameworks. Accordingly, an alternative approach is used that accounts for the clayey nature of the foundation soils. Field and laboratory tests are used to evaluate the monotonic and cyclic shear resistance of the soil, which is compared to the cyclic demand placed on the soil by ground response and soil–structure interaction. Results of the analysis indicate a potential for cyclic softening and associated strength loss in foundation soils below the six-story buildings, which contributes to bearing capacity failures at the edges of the foundation. Similar analyses indicate high factors of safety in foundation soils below one-story buildings as well in the free field, which is consistent with the observed field performance. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A11%281 [...] [article] Cyclic softening of low-plasticity clay and its effect on seismic foundation performance [texte imprimé] / Daniel B. Chu, Auteur ; Stewart, Jonathan P., Auteur ; Ross W. Boulanger, Auteur . - 2009 . - pp. 1595–1608. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°11 (Novembre 2008) . - pp. 1595–1608 Mots-clés : Soil  liquefaction  Seismic  effects  Soil  structure  interaction  Shallow  foundations  In  situ  tests  Taiwan  Earthquakes Résumé : During the 1999 Chi-Chi Earthquake (Mw=7.6) , significant incidents of ground failure occurred in Wufeng, Taiwan, which experienced peak accelerations ∼0.7g . This paper describes the results of field investigations and analyses of a small region within Wufeng along an E–W trending line 350m long. The east end of the line has single-story structures for which there was no evidence of ground failure. The west end of the line had three to six-story reinforced concrete structures that underwent differential settlement and foundation bearing failures. No ground failure was observed in the free field. Surficial soils consist of low-plasticity silty clays that extend to 8–12m depth in the damaged area (west side), and 3–10m depth in the undamaged area (east side). A significant fraction of the foundation soils at the site are liquefaction susceptible based on several recently proposed criteria, but the site performance cannot be explained by analysis in existing liquefaction frameworks. Accordingly, an alternative approach is used that accounts for the clayey nature of the foundation soils. Field and laboratory tests are used to evaluate the monotonic and cyclic shear resistance of the soil, which is compared to the cyclic demand placed on the soil by ground response and soil–structure interaction. Results of the analysis indicate a potential for cyclic softening and associated strength loss in foundation soils below the six-story buildings, which contributes to bearing capacity failures at the edges of the foundation. Similar analyses indicate high factors of safety in foundation soils below one-story buildings as well in the free field, which is consistent with the observed field performance. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A11%281 [...]

Dynamic centrifuge testing of slickensided shear surfaces / Christopher L. Meehan in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°8 (Août 2008) . - pp. 1086–1096 Titre : Dynamic centrifuge testing of slickensided shear surfaces Type de document : texte imprimé Auteurs : Christopher L. Meehan, Auteur ; Ross W. Boulanger, Auteur ; J. Michael Duncan, Auteur Année de publication : 2008 Article en page(s) : pp. 1086–1096 Note générale : Geotechnical and geotechnical engineering Langues : Anglais (eng) Mots-clés : Dynamic  stability  Clays  Residual  strength  Slope  stability  Earthquakes  Soil  deformation  Shear  strength  Overconsolidated  soils  Centrifuge Résumé : Movement along preexisting slickensided rupture surfaces in overconsolidated clay and clay shale slopes can represent a critical sliding mechanism during earthquakes. The seismic behavior of preexisting slickensided surfaces in overconsolidated clay was examined by performing dynamic centrifuge model tests of two slickensided sliding block models constructed using Rancho Solano lean clay. Dynamic shear displacements were concentrated along the preformed slickensided surfaces. The peak shear resistances mobilized along the slickensided surfaces during dynamic loading were 90–120% higher than the drained residual strength measured prior to shaking. To accurately predict the displacements of the sliding blocks using Newmark’s method, it was necessary to use dynamic strengths that were 37–64% larger than the drained residual strength of the soil. Dynamic loading caused a positive pore pressure response in the soil surrounding the slickensided planes. The postshaking shear strengths were 17–31% higher than those measured prior to shaking. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A8%2810 [...] [article] Dynamic centrifuge testing of slickensided shear surfaces [texte imprimé] / Christopher L. Meehan, Auteur ; Ross W. Boulanger, Auteur ; J. Michael Duncan, Auteur . - 2008 . - pp. 1086–1096. Geotechnical and geotechnical engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°8 (Août 2008) . - pp. 1086–1096 Mots-clés : Dynamic  stability  Clays  Residual  strength  Slope  stability  Earthquakes  Soil  deformation  Shear  strength  Overconsolidated  soils  Centrifuge Résumé : Movement along preexisting slickensided rupture surfaces in overconsolidated clay and clay shale slopes can represent a critical sliding mechanism during earthquakes. The seismic behavior of preexisting slickensided surfaces in overconsolidated clay was examined by performing dynamic centrifuge model tests of two slickensided sliding block models constructed using Rancho Solano lean clay. Dynamic shear displacements were concentrated along the preformed slickensided surfaces. The peak shear resistances mobilized along the slickensided surfaces during dynamic loading were 90–120% higher than the drained residual strength measured prior to shaking. To accurately predict the displacements of the sliding blocks using Newmark’s method, it was necessary to use dynamic strengths that were 37–64% larger than the drained residual strength of the soil. Dynamic loading caused a positive pore pressure response in the soil surrounding the slickensided planes. The postshaking shear strengths were 17–31% higher than those measured prior to shaking. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A8%2810 [...]

Dynamic properties of highly organic soils from montezuma slough and clifton court / Tadahiro Kishida in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 4 (Avril 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 525–532 Titre : Dynamic properties of highly organic soils from montezuma slough and clifton court Type de document : texte imprimé Auteurs : Tadahiro Kishida, Auteur ; Timothy M. Wehling, Auteur ; Ross W. Boulanger, Auteur Année de publication : 2009 Article en page(s) : pp. 525–532 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil  properties  Dynamic  properties  Organic  matter  Peat  Shear  modulus  Damping Résumé : The nonlinear dynamic properties of highly organic soils from two levee sites in the Sacramento-San Joaquin Delta in California are described. Cyclic triaxial, resonant column and torsional shear tests were performed on thin-walled tube samples obtained from beneath levee crests, beneath adjacent berms, and in the free field such that the in situ vertical effective stresses (σ′vo) ranged from about 16to67kPa . These highly organic soils had considerably different organic characteristics from those used in previous studies of dynamic properties. The tested samples had organic contents of 14 to 61%, initial water contents (wo) of 88 to 496%, shear wave velocities (Vs) of 20to130m∕s , and organic components that ranged from highly fibrous to highly decomposed and amorphous. Secant shear modulus (G) , normalized secant shear modulus (G∕Gmax) , and equivalent damping ratio (ξ) versus cyclic shear strain amplitude (γc) relations are presented, and their dependence on variables such as consolidation stress, organic content, prior loading history, testing device, and loading frequency are illustrated. Findings are compared to previously published results. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2852 [...] [article] Dynamic properties of highly organic soils from montezuma slough and clifton court [texte imprimé] / Tadahiro Kishida, Auteur ; Timothy M. Wehling, Auteur ; Ross W. Boulanger, Auteur . - 2009 . - pp. 525–532. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 525–532 Mots-clés : Soil  properties  Dynamic  properties  Organic  matter  Peat  Shear  modulus  Damping Résumé : The nonlinear dynamic properties of highly organic soils from two levee sites in the Sacramento-San Joaquin Delta in California are described. Cyclic triaxial, resonant column and torsional shear tests were performed on thin-walled tube samples obtained from beneath levee crests, beneath adjacent berms, and in the free field such that the in situ vertical effective stresses (σ′vo) ranged from about 16to67kPa . These highly organic soils had considerably different organic characteristics from those used in previous studies of dynamic properties. The tested samples had organic contents of 14 to 61%, initial water contents (wo) of 88 to 496%, shear wave velocities (Vs) of 20to130m∕s , and organic components that ranged from highly fibrous to highly decomposed and amorphous. Secant shear modulus (G) , normalized secant shear modulus (G∕Gmax) , and equivalent damping ratio (ξ) versus cyclic shear strain amplitude (γc) relations are presented, and their dependence on variables such as consolidation stress, organic content, prior loading history, testing device, and loading frequency are illustrated. Findings are compared to previously published results. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2852 [...]

Examination and reevalaution of SPT-based liquefaction triggering case histories / Ross W. Boulanger 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. 898–909 Titre : Examination and reevalaution of SPT-based liquefaction triggering case histories Type de document : texte imprimé Auteurs : Ross W. Boulanger, Auteur ; Daniel W. Wilson, Auteur ; I.M. Idriss, Auteur Année de publication : 2012 Article en page(s) : pp. 898–909 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Liquefaction  Earthquakes  Cyclic  loads  Standard  penetration  test Résumé : A standard penetration test (SPT)-based liquefaction case history database for liquefaction triggering criteria is reexamined and reevaluated. The updated database incorporates a number of additional case histories, replaces prior estimates of earthquake magnitudes with current estimates of their moment magnitudes, uses improved estimates of peak ground accelerations when available, and includes a reexamination of the selection and computation of representative SPT (N1)60 values for most case histories. The approach used to select and compute representative SPT (N1)60cs values is illustrated using select case histories. The distribution of the case history data relative to the Idriss-Boulanger triggering correlation is examined for any bias with respect to various parameters and to identify the conditions that are, and are not, well covered by available case history data. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000668 [article] Examination and reevalaution of SPT-based liquefaction triggering case histories [texte imprimé] / Ross W. Boulanger, Auteur ; Daniel W. Wilson, Auteur ; I.M. Idriss, Auteur . - 2012 . - pp. 898–909. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 8 (Août 2012) . - pp. 898–909 Mots-clés : Liquefaction  Earthquakes  Cyclic  loads  Standard  penetration  test Résumé : A standard penetration test (SPT)-based liquefaction case history database for liquefaction triggering criteria is reexamined and reevaluated. The updated database incorporates a number of additional case histories, replaces prior estimates of earthquake magnitudes with current estimates of their moment magnitudes, uses improved estimates of peak ground accelerations when available, and includes a reexamination of the selection and computation of representative SPT (N1)60 values for most case histories. The approach used to select and compute representative SPT (N1)60cs values is illustrated using select case histories. The distribution of the case history data relative to the Idriss-Boulanger triggering correlation is examined for any bias with respect to various parameters and to identify the conditions that are, and are not, well covered by available case history data. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000668

Liquefaction effects on piled bridge abutments / Richard J. Armstrong in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 3 (Mars 2013) 

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Postshaking shear strain localization in a centrifuge model of a saturated sand slope / Erik J. Malvick in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

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Regression models for dynamic properties of highly organic soils / Tadahiro Kishida in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 4 (Avril 2009) 

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