Non-coaxiality of strain increment and stress directions in cross-anisotropic sand

Rodriguez, Nina M.; Lade, Poul V.

doi:10.1016/j.ijsolstr.2013.12.003

Cited by 32 publications

(14 citation statements)

References 32 publications

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“…Non-coaxial sand response refers to an inconsistency of the principal axes of plastic strain increment and those for the stress. It is commonly observed in experimental tests on both naturally deposited and reconstituted sands (Roscoe, 1970;Li and Yu, 2010;Rodriguez and Lade, 2014). Roscoe (1970) is among the first to observe the non-coaxial behaviour in his simple shear tests on sand.…”

Section: Introductionmentioning

confidence: 91%

A non-coaxial critical-state model for sand accounting for fabric anisotropy and fabric evolution

Gao

Zhao

2017

International Journal of Solids and Structures

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Soil fabric and its evolving nature underpin the non-coaxial, anisotropic mechanical behaviour of sand, which has not been adequately recognized by past studies on constitutive modelling. A novel three-dimensional constitutive model is proposed to describe the non-coaxial behaviour of sand within the framework of anisotropic critical state theory. The model features a plastic potential explicitly expressed in terms of a fabric tensor reflecting the anisotropy of soil structure and an evolution law for it. Under monotonic loading, the fabric evolution law characterizes a general trend of the fabric change to gradually become co-directional with the loading direction before the soil reaches the critical state. When a sand is subjected to rotation of principal stress directions, the fabric evolves with the plastic strain increment which is further dependent on the current stress state, the current fabric and the direction of stress increment. During its evolution, the fabric rotates towards the loading direction and reaches a final degree of anisotropy proportional to a normalized stress ratio. With the incorporation of fabric and fabric evolution, the non-coaxial sand behaviour can be easily captured, and the model response converges to be coaxial at the critical state when the stress and fabric are co-directional. The model has been used to simulate the mechanical behaviour of sand subjected to either monotonic loading or continuous rotation of principal stress directions. The model predictions agree well with test data.

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Section: Introductionmentioning

confidence: 91%

A non-coaxial critical-state model for sand accounting for fabric anisotropy and fabric evolution

Gao

Zhao

2017

International Journal of Solids and Structures

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“…Extensive experimental (e.g., [1][2][3][4][5][6]) and micromechanics-based (e.g., [7][8][9][10][11]) evidence has demonstrated that non-coaxiality, which refers to the non-coincidence of the principal axes of the stress and plastic strain rate tensors, is an intrinsic characteristic of granular materials.…”

Section: Introductionmentioning

confidence: 99%

Non-coaxial soil model with an anisotropic yield criterion and its application to the analysis of strip footing problems

Yuan

et al. 2018

Computers and Geotechnics

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This paper presents numerical applications of a non-coaxial soil model, in which an anisotropic yield criterion is incorporated, to analyze two-dimensional strip-footing problems. Semianalytical solutions of the bearing capacity for a strip footing that rests on anisotropic, weightless, cohesive-frictional soils are developed based on the slip line method. The degrees of influences of soil anisotropy and non-coaxiality on the bearing capacity of the strip footing are examined. From the viewpoint of strength and stiffness, it is necessary to incorporate both the strength anisotropy and non-coaxiality into numerical simulations and practical designs of geotechnical problems.

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“…Note that non‐coaxial deformation of granular soils was widely observed in previous experimental studies 2–10,49,50 . Although the flow direction of the hypoplastic model has been modified from m B to m co as mentioned above, the model still cannot simulate the non‐coaxial deformation because both m B and m co are isotropic functions of stress invariants only; thus, they are always coaxial with the stress tensor

σ

.…”

Section: Non‐coaxial Hypoplastic Model For Anisotropic Sandmentioning

confidence: 99%

Non‐coaxial hypoplastic model for sand with evolving fabric anisotropy including non‐proportional loading

Liao

Yang

2021

Num Anal Meth Geomechanics

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Non‐coaxial response refers to the deviation between the directions of the principal stress and plastic strain increment. In this paper, an extended hypoplastic model is proposed based on the anisotropic critical state theory, to describe the non‐coaxial and anisotropic response of sand subjected to both monotonic loading and rotation of principal stress axis. A fabric tensor that characterizes the internal structure of sand is introduced into a hypoplastic model, to reflect the effect of fabric anisotropy on the dilatancy and strength of sand. A Lode‐angle‐dependent hypoplastic potential surface is employed, rendering the flow direction no longer co‐directional with the stress tensor in the deviatoric plane. The fabric tensor is further incorporated into the flow direction, enabling the model to generate a non‐coaxial response. Upon shearing, the fabric evolves toward the loading direction following a properly defined evolution law, and the model response becomes purely coaxial at the critical state when the fabric becomes co‐directional with the loading direction. The tangential loading effect is further introduced to simulate the stiffness degradation of sand during undrained rotational shearing. The model is demonstrated to be capable of simulating the prismatic yet complex anisotropic behavior of sand under both proportional and non‐proportional loading conditions.

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Non-coaxiality of strain increment and stress directions in cross-anisotropic sand

Cited by 32 publications

References 32 publications

A non-coaxial critical-state model for sand accounting for fabric anisotropy and fabric evolution

A non-coaxial critical-state model for sand accounting for fabric anisotropy and fabric evolution

Non-coaxial soil model with an anisotropic yield criterion and its application to the analysis of strip footing problems

Non‐coaxial hypoplastic model for sand with evolving fabric anisotropy including non‐proportional loading

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