Documents disponibles écrits par cet auteur

Effect of footing width on bearing capacity factor Nγ for smooth strip footings / Jyant Kumar 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. 1299–1310 Titre : Effect of footing width on bearing capacity factor Nγ for smooth strip footings Type de document : texte imprimé Auteurs : Jyant Kumar, Auteur ; V. N. Khatri, Auteur Année de publication : 2008 Article en page(s) : pp. 1299–1310 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Footings  Bearing  capacity  Failures  Foundations  Limit  analysis  Numerical  analysis  Optimization Résumé : By incorporating the variation of soil friction angle (ϕ) with mean principal stress (σm) , the effect of footing width (B) on bearing capacity factor Nγ was examined for a smooth strip footing placed on a granular medium without any surcharge pressure. The analysis was performed by means of a numerical lower bound limit analysis in conjunction with finite-elements and linear programming. An iterative computational procedure was framed to account for the dependency of ϕ on σm . Two well-defined ϕ–σm curves from literature associated with Hoston and Toyora sands, corresponding to relative density of 18 and 74.5%, respectively, were used. The magnitude of Nγ was obtained for different footing widths, covering almost the entire range of model and field footing sizes. It was noted that for B greater than about 0.4m , it is possible to relate Nγ with B approximately in a linear fashion on a log–log scale. Further, it was seen that if an average value of ϕ along the footing–soil interface is obtained, it is possible to estimate a reasonable magnitude of Nγ for a given footing width provided the relationship between ϕ and σm is specified for the given material. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2812 [...] [article] Effect of footing width on bearing capacity factor Nγ for smooth strip footings [texte imprimé] / Jyant Kumar, Auteur ; V. N. Khatri, Auteur . - 2008 . - pp. 1299–1310. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°9 (Septembre 2008) . - pp. 1299–1310 Mots-clés : Footings  Bearing  capacity  Failures  Foundations  Limit  analysis  Numerical  analysis  Optimization Résumé : By incorporating the variation of soil friction angle (ϕ) with mean principal stress (σm) , the effect of footing width (B) on bearing capacity factor Nγ was examined for a smooth strip footing placed on a granular medium without any surcharge pressure. The analysis was performed by means of a numerical lower bound limit analysis in conjunction with finite-elements and linear programming. An iterative computational procedure was framed to account for the dependency of ϕ on σm . Two well-defined ϕ–σm curves from literature associated with Hoston and Toyora sands, corresponding to relative density of 18 and 74.5%, respectively, were used. The magnitude of Nγ was obtained for different footing widths, covering almost the entire range of model and field footing sizes. It was noted that for B greater than about 0.4m , it is possible to relate Nγ with B approximately in a linear fashion on a log–log scale. Further, it was seen that if an average value of ϕ along the footing–soil interface is obtained, it is possible to estimate a reasonable magnitude of Nγ for a given footing width provided the relationship between ϕ and σm is specified for the given material. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2812 [...]

Interference of two closely spaced strip footings on sand using model tests / Jyant Kumar 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. 595–604 Titre : Interference of two closely spaced strip footings on sand using model tests Type de document : texte imprimé Auteurs : Jyant Kumar, Auteur ; Manas Kumar Bhoi, Auteur Année de publication : 2009 Article en page(s) : pp. 595–604 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Bearing  capacity  Failures  Foundations  Model  tests  Scale  effect  Sand Résumé : By using small scale model tests, the interference effect on the ultimate bearing capacity of two closely spaced strip footings, placed on the surface of dry sand, was investigated. At any time, the footings were assumed to (1) carry exactly the same magnitude of load; and (2) settle to the same extent. No tilt of the footing was allowed. The effect of clear spacing (s) between two footings was explicitly studied. An interference of footings leads to a significant increase in their bearing capacity; the interference effect becomes even more substantial with an increase in the relative density of sand. The bearing capacity attains a peak magnitude at a certain (critical) spacing between two footings. The experimental observations presented in this technical note were similar to those given by different available theories. However, in a quantitative sense, the difference between the experiments and theories was seen to be still significant and it emphasizes the need of doing a further rigorous analysis in which the effect of stress level on the shear strength parameters of soil mass can be incorporated properly. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2859 [...] [article] Interference of two closely spaced strip footings on sand using model tests [texte imprimé] / Jyant Kumar, Auteur ; Manas Kumar Bhoi, Auteur . - 2009 . - pp. 595–604. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 4 (Avril 2009) . - pp. 595–604 Mots-clés : Bearing  capacity  Failures  Foundations  Model  tests  Scale  effect  Sand Résumé : By using small scale model tests, the interference effect on the ultimate bearing capacity of two closely spaced strip footings, placed on the surface of dry sand, was investigated. At any time, the footings were assumed to (1) carry exactly the same magnitude of load; and (2) settle to the same extent. No tilt of the footing was allowed. The effect of clear spacing (s) between two footings was explicitly studied. An interference of footings leads to a significant increase in their bearing capacity; the interference effect becomes even more substantial with an increase in the relative density of sand. The bearing capacity attains a peak magnitude at a certain (critical) spacing between two footings. The experimental observations presented in this technical note were similar to those given by different available theories. However, in a quantitative sense, the difference between the experiments and theories was seen to be still significant and it emphasizes the need of doing a further rigorous analysis in which the effect of stress level on the shear strength parameters of soil mass can be incorporated properly. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A4%2859 [...]

Miniature cone tip resistance of sand with fly ash using triaxial setup / Jyant Kumar in Canadian geotechnical journal, Vol. 46 N° 2 (Fevrier 2009) 

Public ISBD [article]  in Canadian geotechnical journal > Vol. 46 N° 2 (Fevrier 2009) . - pp. 231–240 Titre : Miniature cone tip resistance of sand with fly ash using triaxial setup Type de document : texte imprimé Auteurs : Jyant Kumar, Auteur ; K. V.S.B. Raju, Auteur Article en page(s) : pp. 231–240 Note générale : Science de la Terre Langues : Anglais (eng) Mots-clés : Cone  penetrometer  Test  laboratory  investigations  Sand  Shear  strength  Fly  ash  Essais  de  pénétration  au  cône  Recherches  au  laboratoire  Sable  Résistance  au  cisaillement  Cendres  volantes Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : In a continuation of the authors’ recent work, the ultimate tip resistance of a miniature cone using triaxial equipment was determined for samples of dry sand mixed with dry fly ash. The effect of (i) the proportion of fly ash, (ii) the relative density of samples, and (iii) the vertical overburden pressure was examined. It was noted that an addition of fly ash in sand for the same range of relative density leads to a significant reduction in the ultimate tip resistance of the cone (qcu). This occurs due to a decrease in the friction angle () of the sample with an increase in the fly ash content for a given relative density. For greater than about 30°, two widely used correlation curves from published literature, providing the relationships between qcu and for cohesionless soils, were found to provide satisfactory predictions, even for sand – fly ash mixtures. As was expected, the values of qcu increase continuously with an increase in the relative density of the soil mass and the vertical effective (overburden) stress on the sample. Pour faire suite aux récents travaux faits par les auteurs, la résistance ultime de la pointe d’un cône miniature a été déterminé pour des échantillons de sable sec mélangé avec des cendres volantes sèches. Les effets suivants ont été examinés : (i) la proportion de cendres volantes, (ii) la densité relative des échantillons et (iii) la pression des terres sus-jacentes. Il a été observé que l’ajout de cendres volantes dans le sable, pour des densités relatives similaires, entraîne une réduction importante de la résistance ultime de la pointe du cône (qcu). Ceci est dû à une diminution de l’angle de friction () de l’échantillon avec l’augmentation de la teneur en cendres volantes pour une densité donnée. Pour supérieur à environ 30°, deux courbes de corrélation (provenant de la littérature) communément utilisées, qui expriment les relations entre qcu et pour des sols sans cohésion, ont fourni des prédictions satisfaisantes même pour les mélanges sable-cendres volantes. Tel que prévu, les valeurs de qcu augmentent continuellement avec une augmentation de la densité relative du sol et de la contrainte effective verticale (pression des terres) sur les échantillons. DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...] [article] Miniature cone tip resistance of sand with fly ash using triaxial setup [texte imprimé] / Jyant Kumar, Auteur ; K. V.S.B. Raju, Auteur . - pp. 231–240. Science de la Terre Langues : Anglais (eng) in Canadian geotechnical journal > Vol. 46 N° 2 (Fevrier 2009) . - pp. 231–240 Mots-clés : Cone  penetrometer  Test  laboratory  investigations  Sand  Shear  strength  Fly  ash  Essais  de  pénétration  au  cône  Recherches  au  laboratoire  Sable  Résistance  au  cisaillement  Cendres  volantes Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : In a continuation of the authors’ recent work, the ultimate tip resistance of a miniature cone using triaxial equipment was determined for samples of dry sand mixed with dry fly ash. The effect of (i) the proportion of fly ash, (ii) the relative density of samples, and (iii) the vertical overburden pressure was examined. It was noted that an addition of fly ash in sand for the same range of relative density leads to a significant reduction in the ultimate tip resistance of the cone (qcu). This occurs due to a decrease in the friction angle () of the sample with an increase in the fly ash content for a given relative density. For greater than about 30°, two widely used correlation curves from published literature, providing the relationships between qcu and for cohesionless soils, were found to provide satisfactory predictions, even for sand – fly ash mixtures. As was expected, the values of qcu increase continuously with an increase in the relative density of the soil mass and the vertical effective (overburden) stress on the sample. Pour faire suite aux récents travaux faits par les auteurs, la résistance ultime de la pointe d’un cône miniature a été déterminé pour des échantillons de sable sec mélangé avec des cendres volantes sèches. Les effets suivants ont été examinés : (i) la proportion de cendres volantes, (ii) la densité relative des échantillons et (iii) la pression des terres sus-jacentes. Il a été observé que l’ajout de cendres volantes dans le sable, pour des densités relatives similaires, entraîne une réduction importante de la résistance ultime de la pointe du cône (qcu). Ceci est dû à une diminution de l’angle de friction () de l’échantillon avec l’augmentation de la teneur en cendres volantes pour une densité donnée. Pour supérieur à environ 30°, deux courbes de corrélation (provenant de la littérature) communément utilisées, qui expriment les relations entre qcu et pour des sols sans cohésion, ont fourni des prédictions satisfaisantes même pour les mélanges sable-cendres volantes. Tel que prévu, les valeurs de qcu augmentent continuellement avec une augmentation de la densité relative du sol et de la contrainte effective verticale (pression des terres) sur les échantillons. DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...]

Vertical uplift resistance of a group of two coaxial anchors in clay / Jyant Kumar in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 3 (Mars 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 3 (Mars 2012) . - pp. 419-422 Titre : Vertical uplift resistance of a group of two coaxial anchors in clay Type de document : texte imprimé Auteurs : Jyant Kumar, Auteur Année de publication : 2012 Article en page(s) : pp. 419-422 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Anchors  Clays  Failure  Finite  elements  Limit  analysis  Optimization Résumé : The vertical uplift resistance for a group of two horizontal coaxial rigid strip anchors embedded in clay under undrained condition has been determined by using the upper bound theorem of limit analysis in combination with finite elements. An increase of undrained shear strength of soil mass with depth has been incorporated. The uplift factor Fcγ has been computed. As compared to a single isolated anchor, a group of two anchors provides greater magnitude of the uplift resistance. For a given embedment ratio, the group of two anchors generates almost the maximum uplift resistance when the upper anchor is located midway between ground surface and the lower anchor. For a given embedment ratio, Fcγ increases linearly with an increase in the normalized unit weight of soil mass up to a certain value before attaining a certain maximum magnitude; the maximum value of Fcγ increases with an increase in embedment ratio. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v138/i3/p419_s1?isAuthorized=no [article] Vertical uplift resistance of a group of two coaxial anchors in clay [texte imprimé] / Jyant Kumar, Auteur . - 2012 . - pp. 419-422. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 3 (Mars 2012) . - pp. 419-422 Mots-clés : Anchors  Clays  Failure  Finite  elements  Limit  analysis  Optimization Résumé : The vertical uplift resistance for a group of two horizontal coaxial rigid strip anchors embedded in clay under undrained condition has been determined by using the upper bound theorem of limit analysis in combination with finite elements. An increase of undrained shear strength of soil mass with depth has been incorporated. The uplift factor Fcγ has been computed. As compared to a single isolated anchor, a group of two anchors provides greater magnitude of the uplift resistance. For a given embedment ratio, the group of two anchors generates almost the maximum uplift resistance when the upper anchor is located midway between ground surface and the lower anchor. For a given embedment ratio, Fcγ increases linearly with an increase in the normalized unit weight of soil mass up to a certain value before attaining a certain maximum magnitude; the maximum value of Fcγ increases with an increase in embedment ratio. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v138/i3/p419_s1?isAuthorized=no