Stress Dilatancy and Fabric Dependencies on Sand Behavior

Wan, Richard; Guo, Pei

doi:10.1061/(asce)0733-9399(2004)130:6(635)

Cited by 103 publications

(48 citation statements)

References 34 publications

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“…numerical results shows, however, that the calculated stiffness is too high before the peak (in the hardening regime). The computed thickness of the shear zone is slightly larger (by 10-15%) than the thickness in experiments (determined by means of x-rays [73]). Moreover, the calculated inclination of the shear zone to the horizontal is smaller than the experimental by 2-4 • .…”

Section: Problem With Smooth Boundariesmentioning

confidence: 52%

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Non‐coaxiality and stress–dilatancy rule in granular materials: FE investigation within micro‐polar hypoplasticity

Tejchman

Wu²

2008

Num Anal Meth Geomechanics

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SUMMARYThis paper deals with FE investigations of shear localization in dilatant granular bodies. The calculations were carried out with a hypoplastic constitutive law enhanced by micro-polar terms to properly model the shear zone evolution. The behaviour of an initially medium dense sand specimen with very smooth and very rough horizontal boundaries was analyzed during a plane strain compression test. A stochastic distribution of the initial void ratio was assumed to be spatially correlated. Attention was focused on the non-coaxiality of the directions of the principal strain increments and principal stresses in the shear zone and on the stress-dilatancy rule.

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Section: Problem With Smooth Boundariesmentioning

confidence: 52%

“…In addition, Wan and Guo [73] proposed the following stress-dilatancy formula without taking into account the effect of non-coaxiality:…”

Section: Non-coaxiality and Stress-dilatancy Rule In 2d Granular Matementioning

confidence: 99%

Non‐coaxiality and stress–dilatancy rule in granular materials: FE investigation within micro‐polar hypoplasticity

Tejchman

Wu²

2008

Num Anal Meth Geomechanics

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“…dilatancy) through energy principles [20,21] and (b) critical state concept which defines a theoretical state at which the material is continuously distorted under no change in volume and stress ratio [22,23]. These two frameworks were enriched to incorporate pyknotropy (density), barotropy (stress level), as well as anisotropy (fabric) dependencies, and to address cyclic loading regime conditions [24][25][26]. In the following subsection, we propose and present an ad hoc generalization of WG model to three-dimensional stress-strain conditions.…”

Section: Density-stress-fabric Dependent Constitutive Modelmentioning

confidence: 99%

Elastoplastic modelling of diffuse instability response of geomaterials

Wan

Pinheiro

Guo

2011

Num Anal Meth Geomechanics

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SUMMARYIn this paper, we study material instabilities in geomaterials through an elastoplastic constitutive model endowed with appropriate attributes, such as stress, density and fabric dependencies. The analyses reveal the possibility of having diffuse instability, bifurcation and loss of uniqueness within the plastic limit surface. The resulting domain of bifurcation encompasses the intrinsic effects of stress-strain history, direction of loading, type of loading and fabric. The computations start at a material point level and are later on extended to an initial boundary value setting where diffuse failure of a three-dimensional sand specimen with a random distribution of void ratio is examined. We restrict our simulations to the study of a q-constant laboratory experimental test under different sets of control parameters. Diffuse failure is also revealed in a slope analysis under water infiltration following similar loading paths as in the q-constant test. The analysis shows common material instability features observed in the above test.

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“…Strength anisotropy is of key engineering importance in estimating the stability of infrastructures and has therefore attracted much research interest. Extensive efforts of experimental testing and constitutive modelling have been made to better estimate the strength and deformation of anisotropic granular soils [2,3,5,6,9,19,22,27,29,32,34,42]. Experiments have been carried out by preparing and testing specimens of different tilting angles or loading a soil specimen along various directions [20,29,30,45].…”

Section: Introductionmentioning

confidence: 99%

“…It has become increasingly popular as particle-scale information has been made more accessible nowadays [10,14,18]. The fabric tensor has been proposed to characterize material structure and incorporated in constitutive model development to better capture the material behaviour [27,33,40,42]. Challenges remain on establishing the correlation between the proposed fabric tensors and the key characteristics of material constitutive behaviours.…”

Section: Introductionmentioning

confidence: 99%

Fabric, force and strength anisotropies in granular materials: a micromechanical insight

2014

Acta Mech

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In micromechanics, the stress-force-fabric (SFF) relationship is referred to as an analytical expression linking the stress state of a granular material with microparameters on contact forces and material fabric. This paper employs the SFF relationship and discrete element modelling to investigate the micromechanics of fabric, force and strength anisotropies in two-dimensional granular materials. The development of the SFF relationship is briefly summarized while more attention is placed on the strength anisotropy and deformation non-coaxiality. Due to the presence of initial anisotropy, a granular material demonstrates a different behaviour when the loading direction relative to the direction of the material fabric varies. Specimens may go through various paths to reach the same critical state at which the fabric and force anisotropies are coaxial with the loading direction. The critical state of anisotropic granular material has been found to be independent of the initial fabric. The fabric anisotropy and the force anisotropy approach their critical magnitudes at the critical state. The particle-scale data obtained from discrete element simulations of anisotropic materials show that in monotonic loading, the principal force direction quickly becomes coaxial with the loading direction (i.e. the strain increment direction as applied). However, material fabric directions differ from the loading direction and they only tend to be coaxial at a very large shear strain. The degree of force anisotropy is in general larger than that of fabric anisotropy. In comparison with the limited variation in the degree of force anisotropy with varying loading directions, the fabric anisotropy adapts in a much slower pace and demonstrates wider disparity in the evolution in the magnitude of fabric anisotropy. The difference in the fabric anisotropy evolution has a more significant contribution to strength anisotropy than that of force anisotropy. There are two key parameters that control the degree of deformation non-coaxiality in granular materials subjected to monotonic shearing: the ratio between the degrees of fabric anisotropy and that of force anisotropy and the angle between the principal fabric direction and the applied loading direction.

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Stress Dilatancy and Fabric Dependencies on Sand Behavior

Cited by 103 publications

References 34 publications

Non‐coaxiality and stress–dilatancy rule in granular materials: FE investigation within micro‐polar hypoplasticity

Non‐coaxiality and stress–dilatancy rule in granular materials: FE investigation within micro‐polar hypoplasticity

Elastoplastic modelling of diffuse instability response of geomaterials

Fabric, force and strength anisotropies in granular materials: a micromechanical insight

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