SANISAND‐FN: An evolving fabric‐based sand model accounting for stress principal axes rotation

Petalas, Alexandros L.; Dafalias, Yannis F.; Papadimitriou, Achilleas G.

doi:10.1002/nag.2855

Cited by 82 publications

(63 citation statements)

References 53 publications

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“…It is important to notice that the DEM results are accommodated by the premises of ACST in a general descriptive way, based on how the basic entities of the theory are defined by those results, but no exact simulation by a constitutive model within ACST was made nor was it intended to be made, because no full constitutive formulation is provided. Equations and are fundamental equations of ACST and together with the generic constitutive Equations and can be incorporated in various specific constitutive modeling approaches within ACST, as for example in the SANISAND‐FR (Papadimitriou et al) and SANISAND‐FN (Petalas et al) models.…”

Section: Interpretation Of Dem Results Within Acstmentioning

confidence: 99%

“…Based on this new ingredient, it was possible to interpret during the aforementioned 3D DEM experiment the stress‐strain results by combining the DEM findings for the fabric‐related quantities with the basic equations proposed in ACST, thus, proving its relevance not only in regard to CS but also in relation to the response before and after CS is reached. In addition, this FAV A proved to be invaluable in simulating strongly anisotropic granular material response (eg, Yoshimine et al) as firstly shown by Li and Dafalias and sequentially by a number of ACST‐based constitutive models (eg, Papadimitriou et al, Petalas et al).…”

Section: Discussionmentioning

confidence: 99%

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Necessary and sufficient conditions for reaching and maintaining critical state

Theocharis

Vairaktaris

Dafalias

et al. 2019

Num Anal Meth Geomechanics

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Summary According to classical critical state theory (CST) of granular mechanics, two analytical conditions on the ratio of stress invariants and the void ratio are postulated to be necessary and sufficient for reaching and maintaining critical state (CS). The present work investigates the sufficiency of these two conditions based on the results of a virtual three‐dimensional discrete element method experiment, which imposes continuous rotation of the principal axes of stress with fixed stress principal values at CS. Even though the fixity of the stress principal values satisfies the two analytical CST conditions at the initiation of rotation, contraction and abandonment of CS occur, which proves that these conditions may be necessary but are not sufficient to maintain CS. But if fixity of stress and strain rate directions in regard to the sample is considered at CS, the two analytical conditions of CST remain both necessary and sufficient. The recently proposed anisotropic critical state theory (ACST) turned this qualitative requirement of fixity into an analytical condition related to the CS value of a fabric anisotropy variable A defined in terms of an evolving fabric tensor and the plastic strain rate direction, thus, enhancing the two CST conditions by a third. In this way, the three analytical conditions of ACST become both necessary and sufficient for reaching and maintaining CS. In addition, the use of A explains the observed results by relating the stress‐strain response, in particular the dilatancy, to the evolution of fabric by means of the relevant equations of ACST.

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Section: Interpretation Of Dem Results Within Acstmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Necessary and sufficient conditions for reaching and maintaining critical state

Theocharis

Vairaktaris

Dafalias

et al. 2019

Num Anal Meth Geomechanics

Self Cite

View full text Add to dashboard Cite

show abstract

“…Note that a recently published new version of Sanisand [Petalas et al, 2019] is able to predict the measured contractant behavior in the hollow cylinder test of Figs. 20 to 24.…”

Section: Variations In Strain Components With Number Of Cyclesmentioning

confidence: 99%

Comparative performance of some constitutive models in stress rotation

Schranz¹,

Fellin²,

Kolymbas³

2019

Open Geomechanics

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The dilatancy/contractancy of soil is of particular importance for compaction, consolidation, liquefaction, etc. Interestingly, constitutive relations are often unsatisfactory in modelling volume changes in the sense that their predictions deviate considerably from each other. This scatter is pronounced in problems with stress rotation. Therefore, in this paper some selected constitutive relations are investigated with respect to their performance at stress rotation. The obtained numerical simulations are compared with each other and also with experimental results from the 1γ2ε and the hollow cylinder apparatuses.

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“…However, this equation has a shortcoming, especially under the drained condition. Petalas et al [22] pointed out that during the simulation of drained PSR loading, if the sample is initially denser than critical, the value of b (already being larger than ) will increase due to its dependence on the state parameter (14) where h 0r and r are new model parameters associated with the PSR. In order to make K pr more sensitive to the stress ratio, r is usually larger than unity.…”

Section: The Modified Psr Soil Modelmentioning

confidence: 99%

Effects of the principal stress rotation in numerical simulations of geotechnical laboratory cyclic tests

Wang

Yang

et al. 2019

Computers and Geotechnics

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Cyclic stress paths in geotechnical experiments can generate considerable principal stress rotation (PSR) in the saturated soil. The PSR without changes of principal stress magnitudes can generate additional excess pore water pressures and plastic strains, thus accelerating liquefactions in undrained conditions. This paper simulates a series of laboratory tests considering the PSR using two types of sand. The impact of PSR is taken into account by using an elastoplastic soil model developed on the basis of a kinematic hardening soil model with the bounding surface concept. The soil model considers the PSR by treating the stress rate generating the PSR independently. The capability of this soil model is verified by comparing the numerical predictions with and without PSR, as well as experimental results. The comparative results indicate that the simulation with the soil model considering the PSR can better reproduce the test results on the development of shear strain, reduction of effective confining pressure and liquefaction than the soil model without PSR. Therefore, it is important to consider PSR effects in simulations of geotechnical experiments under cyclic loadings.

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SANISAND‐FN: An evolving fabric‐based sand model accounting for stress principal axes rotation

Cited by 82 publications

References 53 publications

Necessary and sufficient conditions for reaching and maintaining critical state

Necessary and sufficient conditions for reaching and maintaining critical state

Comparative performance of some constitutive models in stress rotation

Effects of the principal stress rotation in numerical simulations of geotechnical laboratory cyclic tests

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