Drained Deformation Behavior of Anisotropic Sands during Cyclic Rotation of Principal Stress Axes

Tong, Zhaoxia; Zhang, Jianmin; Yu, Yong; Zhang, Ga

doi:10.1061/(asce)gt.1943-5606.0000378

Cited by 117 publications

(138 citation statements)

References 23 publications

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“…As previously reported, the specimen approaches a denser state at the higher stress ratio. This is similar to the experimental observation reported on the drained response of sand under rotational shear [9,35]; and shares the same mechanism with the larger pore pressure build-up at higher stress ratio in the undrained rotational shear [36,37].…”

Section: Volume Contractionsupporting

confidence: 80%

“…These are clear evidences of plastic deformation caused by rotation of principal stress axes. Similar observations have been reported in experimental hollow cylinder test results on sand [9,35]. …”

Section: Strain Componentssupporting

confidence: 79%

“…It varies between 30 • and 40 • . The degree of non-coaxiality is smaller, i.e., the deformation is more coax- ial when the stress ratio gets higher, consistent with previous numerical and experimental observations [7][8][9]27,35].…”

Section: Deformation Non-coaxialitysupporting

confidence: 78%

“…The strain trajectories gradually approaches circular and become closed as rotation continues. A larger strain trajectory is observed at a greater stress ratio, similar to previous numerical and experimental observations [8,9,27,35]. However experimental observations report elliptical strain trajectories [35].…”

Section: Strain Trajectoriessupporting

confidence: 77%

“…Arthur et al [4] applied controlled changes of principal stress axes with the Directional Shear Cell and studied sample behaviour to shearing after a pre-loading to a high stress ratio and a rotation of principal stress axes. Extensive experimental observations on sand responses to principal stress rotation have been published since the 1980s' [5][6][7][8][9][10] using the hollow cylindrical device which offers independent control of the magnitudes and directions of principal stresses. Non-coaxial deformation and volume contraction are typical deformation characteristics observed when rotating the principal stress axes [6,7,[11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

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Macro deformation and micro structure of 3D granular assemblies subjected to rotation of principal stress axes

Yang

2016

Granular Matter

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This paper presents a numerical investigation on the behavior of three dimensional granular materials during continuous rotation of principal stress axes using the discrete element method. A dense specimen has been prepared as a representative element using the deposition method and subjected to stress rotation at different deviatoric stress levels. Significant plastic deformation has been observed despite that the principal stresses are kept constant. This contradicts the classical plasticity theory, but is in agreement with previous laboratory observations on sand and glass beads. Typical deformation characteristics, including volume contraction, deformation non-coaxiality, have been successfully reproduced. After a larger number of rotational cycles, the sample approaches the ultimate state with constant void ratio and follows a periodic strain path. The internal structure anisotropy has been quantified in terms of the contact-based fabric tensor. Rotation of principal stress axes densifies the packing, and leads to the increase in coordination numbers. A cyclic rotation in material anisotropy has been observed. The larger the stress ratio, the structure becomes more anisotropic. A larger fabric trajectory suggests more significant structure re-organization when rotating and explains the occurrence of more significant strain rate. The trajectory of the contactnormal based fabric is not centered in the origin, due to the anisotropy in particle orientation generated during sample generation which is persistent throughout the shearing process. The sample sheared at a lower intermediate principal stress ratio (b = 0.0) has been observed to approach a smaller strain trajectory as compared to the case b = 0.5, consistent with a smaller fabric trajectory and less significant structural re-organisation. It also experiences less volume contraction with the out-of plane strain component being dilative.

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Section: Volume Contractionsupporting

confidence: 80%

Section: Strain Componentssupporting

confidence: 79%

Section: Deformation Non-coaxialitysupporting

confidence: 78%

Section: Strain Trajectoriessupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

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Macro deformation and micro structure of 3D granular assemblies subjected to rotation of principal stress axes

Yang

2016

Granular Matter

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Describing inherently anisotropic behaviours of natural clay by a hypoplastic model

Fu,

Zhou,

Gong

et al. 2024

Geological Journal

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The purpose of this paper is to model the loading direction‐dependent behaviours of inherently anisotropic intact clay by means of the hypoplastic framework. The basic hypoplastic model for clays proposed by Mašín (2013) is enhanced by incorporating a predefined anisotropic asymptotic state boundary surface formulation which is based on an anisotropic variable by projecting the microstructure tensor onto the normal of the spatially mobilized plane. The capability of the proposed hypoplastic model is first illustrated by simulations of intact Wenzhou soft clay under drained torsional shear tests using the hollow cylinder apparatus. The model is then used to predict undrained shear results on San Francisco Bay mud. Comparisons between the predicted and measured results demonstrate that the proposed hypoplastic model is capable of modelling the combined effect of the principal stress direction and intermediate principal stress on the stress‐strain behaviour of natural soft clay with inherent anisotropy.

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Discrete element method analysis of non‐coaxial flow under rotational shear

Tong

Dafalias

et al. 2014

Num Anal Meth Geomechanics

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SUMMARYThis study focuses on non-coaxial flow behavior of cohesionless soil undergoing cyclic rotational shear, with a special interest in the effects of particle-scale characteristics. To this end, we perform a series of 2D discrete element simulations with various particle shapes, inter-particle coefficient of friction, initial density, and stress ratios. The validity and efficacy of the numerical model is established by systematically comparing numerical simulation results with existing laboratory testing results. Such comparison shows that the numerical simulations are capable of capturing mechanical behavior observed in laboratory testing under rotational shear. We further demonstrate and quantify a strong yet simple relationship between the deviatoric part of the normalized strain increment and the non-coaxial angle, denoted by Δε ð Þ R q and ψ, respectively. This quantitative correlation between ψ and Δε ð Þ R q is independent of applied stress ratio, initial and current void ratio, and the number of cycles applied, but dependent on the principal stress orientation and particle-scale characteristics. At the same Δε ð Þ R q , specimens with higher inter-particle friction angle or smaller particle aspect ratio show greater non-coaxial angles. A simple model ψ ¼ 45 ∘ m Δε ð Þ R q is able to fit this ψ-Δε ð Þ R q relationship well, which provides a useful relationship that can be exploited in developing constitutive models for rotational shearing.

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Drained Deformation Behavior of Anisotropic Sands during Cyclic Rotation of Principal Stress Axes

Cited by 117 publications

References 23 publications

Macro deformation and micro structure of 3D granular assemblies subjected to rotation of principal stress axes

Macro deformation and micro structure of 3D granular assemblies subjected to rotation of principal stress axes

Describing inherently anisotropic behaviours of natural clay by a hypoplastic model

Discrete element method analysis of non‐coaxial flow under rotational shear

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