Comportement non drainé du sable d’Hostun lâche

Konrad, Jean‐Marie; Flavigny, É.; Meghachou, Mourad

doi:10.1051/geotech/1991054053

Cited by 14 publications

(4 citation statements)

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“…A completely different undrained behaviour was revealed in the early works on loose soil by Casagrande (1975), Castro (1969), and Poulos (1981). Since then, experimental works on this topic continued to appear, advancing progressively on the study of some influencing factors: the effects of undrained preshear (Ishihara and Okada 1978b); the influence of an initial static deviatoric stress (Kramer and Seed 1988;Lade et al 1988;Canou et al 1991); the paramount importance of initial density (Konrad et al 1991;Verdugo and Ishihara 1996) and sample preparation methods (Vaid et al 1999); the dependence on the preloading history (Di Prisco et al 1995); in particular, the anisotropic consolidation Kato et al 2001). New concepts were introduced to explain the newly observed behaviour: the steady state of deformation by Castro (1969), the concept of state parameter by Been and Jefferies (1985), the Lade instability lines (Lade et al 1988), the Sladen collapse surface (Sladen et al 1985), and the Konrad conceptual framework (Konrad 1993) on the steady state of deformation based on triaxial compression tests on virgin isotropic consolidated materials.…”

Section: Introductionmentioning

confidence: 98%

Undrained anisotropy of Hostun RF loose sand: new experimental investigations

Finge¹,

Doanh²,

Dubujet³

2006

Can. Geotech. J.

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The undrained behaviour of loose and overconsolidated Hostun RF sand in triaxial compression and extension tests is described. The samples are isotropically or anisotropically overconsolidated along several constant effective stress ratio paths with various overconsolidation ratios (OCR), up to 24. To minimize the effect of variation of density on the observed undrained behaviour, all tested samples are required to have a nearly identical void ratio before the final monotonic undrained shearing. Isotropically overconsolidated and normally consolidated samples exhibit the same phenomenon of partial static liquefaction, but anisotropically overconsolidated specimens reveal a completely different undrained behaviour. A common pseudoelastic response is observed for a given overconsolidation history. This response is induced by recent stress history in terms of effective stress paths, independent of the OCR during overconsolidation. The initial gradient of the effective stress paths seems to depend solely on the direction of the previous linear stress path history. This paper offers a comprehensive understanding of the mechanism of the induced anisotropy of loose sand created by simple linear stress paths from three different initial stress states in the classical triaxial plane. The pseudoelastic response can be adequately modelled by a simple hyperelastic component of the elastoplastic framework.Résumé : Cet étudie le comportement non drainé de sable Hostun RF très lâche et surconsolidé à l'appareil triaxial. Les échantillons sont surconsolidés isotropiquement ou anisotropiquement le long des chemins linéaires de rapport de contraintes constant avec plusieurs valeurs du rapport de surconsolidation, jusqu'à 24. L'indice des vides de tous les échantillons testés est pratiquement identique dans le but de minimiser son influence éventuelle sur le comportement observé. Tandis que la surconsolidation isotrope montre le phénomène de liquéfaction statique qui est un comportement non drainé très semblable à celui de la consolidation isotrope vierge, la surconsolidation anisotrope indique un comportement complètement différent. Pour chaque chemin de surconsolidation, on observe une réponse pseudo-élastique indépendamment du rapport de surconsolidation. Il semble que l'inclinaison initiale des chemins de contraintes effectives ne dépend que de la direction des préchargements. Cet article a permis une compréhension détaillée du mécanisme de l'anisotropie induite des sables lâches créée par les chemins simples de contraintes linéaires à partir de plusieurs états initiaux de contrainte dans le plan triaxial classique. La réponse pseudo-élastique peut ètre simuler par un simple modèle hyperélastique de l'élastoplasticité.Mots clés : anisotropie induite, surconsolidation, instabilité, essais non drainés, hyperélasticité.

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Section: Introductionmentioning

confidence: 98%

Undrained anisotropy of Hostun RF loose sand: new experimental investigations

Finge¹,

Doanh²,

Dubujet³

2006

Can. Geotech. J.

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“…Con objeto de conocer su comportamiento resistente, se han realizado un gran número de ensayos triaxiales a compresión tanto drenados como sin drenaje, en los que se han variado las tensiones de confinamiento y las densidades relativas con las que se preparaban las probetas. Dentro de este marco, caben destacar los trabajos realizados por Konrad et al (1991) y por Gajo y Wood (1999).…”

Section: Materials Ensayadounclassified

“…En la figura 3.1 pueden verse algunos de los resultados de los ensayos triaxiales realizados por Konrad (1991). Figura 3.1: Ensayos triaxiales sin drenaje realizados con probetas de la misma densidad inicial y diferentes presiones de confinamiento.…”

Section: Materials Ensayadounclassified

“…A partir de estos gráficos, y teniendo en cuenta la forma de las curvas tensióndeformación para elevadas deformaciones, se ha determinado la pendiente de la Línea de Estado Crítico, obteniéndose un valor de 1,29, correspondiente a un ángulo de rozamiento de unos 32°. Este valor es del mismo orden de magnitud, aunque un poco superior, al que se recoge en la bibliografía (Konrad et al, 1991y Gajo y Wood, 1999, en la que establece un valor del ángulo de rozamiento, en esas condiciones de deformación crítica, entre 30 y 31°.…”

Section: Ensayos Triaxialesunclassified

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Comportamiento de cimentaciones superficiales sobre suelos granulares sometidas a solicitaciones dinámicas.

Gepp¹

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Undrained instability of very loose Hostun sand in triaxial compression and extension. Part 1: experimental observations

Doanh

Ibraim

Matiotti

1997

Mech. Cohes.-Frict. Mater.

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The undrained behavior of very loose Hostun RF sand in triaxial compression and extension tests is described. The samples are consolidated isotropically or anisotropically along constant effective stress ratio paths. Very loose sand exhibits partial liquefaction, deviator peak stress at relatively low to very low axial strain, gradual post‐peak stress reduction to a small residual value at large strains, sharp loss of effective mean pressure due to generation of large pore pressure and overall volume reduction. The instability line of Lade is examined in the case of extension tests and extended for anisotropic samples. It is shown that monotonic and anisotropic consolidation strongly influences the instability concept. A higher positive anisotropic consolidation level produces a greater slope of the instability line in compression and a reverse trend can occur in extension. Complex stress history can develop a fossilized instability line depending on the amount of axial strain attained. Effective strain ratio increment at peak has an asymptotic stabilization effect. © 1997 by John Wiley & Sons, Ltd.

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Comportement non drainé du sable d’Hostun lâche

Cited by 14 publications

References 1 publication

Undrained anisotropy of Hostun RF loose sand: new experimental investigations

Undrained anisotropy of Hostun RF loose sand: new experimental investigations

Comportamiento de cimentaciones superficiales sobre suelos granulares sometidas a solicitaciones dinámicas.

Undrained instability of very loose Hostun sand in triaxial compression and extension. Part 1: experimental observations

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