Formulation of Anisotropic Strength Criteria for Cohesionless Granular Materials

Cao, Wei; Wang, Rui; Zhang, Jianmin

doi:10.1061/(asce)gm.1943-5622.0000861

Cited by 14 publications

(8 citation statements)

References 31 publications

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“…The initial fabric tensor norm of the four tests is the same, thus Figure 3B shows that A n decreases with increasing δ . Therefore, smaller δ corresponds to smaller C in Equation (13), resulting in greater H and greater peak strength, matching the physical and numerical test observations 62–67 …”

Section: Model Formulation Unifying the Effects Of Principal Stress Vsupporting

confidence: 74%

“…This is a debatable issue, as there are both tests showing smallest peak stress ratio at α = 60° 35,81 and α = 90° 82–84 . The present model does not consider this minimum shear strength at α = 60°, but if it were found to be desired, variations of the strength formulation by Cao et al 62 can be adopted in the formulation of the peak mobilized stress ratio surface.…”

Section: Model Performance For Laboratory Tests On Toyoura Sandmentioning

confidence: 95%

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Three‐dimensional anisotropic plasticity model for sand subjected to principal stress value change and axes rotation

Xue

Pan

et al. 2020

Num Anal Meth Geomechanics

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A three‐dimensional (3D) anisotropic plasticity model for sand is formulated in this study to provide a constitutive description for both radial and principal stress axes rotation (PSAR) loading‐induced behavior under various conditions with a single set of model parameters. The model has zero elastic range, with plastic loading and flow direction dependent on both current stress and stress rate direction. Fabric tensor is introduced along with its evolution to achieve anisotropic plastic modulus, dilatancy, and flow rule formulations. Increase in plastic modulus under continuous PSAR achieves eventual convergence of strain accumulation. A unique decomposition of dilatancy controls the overall contraction and periodic dilatancy oscillation under PSAR. The performance of the model is first thoroughly evaluated based on drained/undrained, monotonic shear/PSAR tests on Toyoura sand, showing its effectiveness in reproducing the behavior of real sand. Discrete element method numerical test results are then adopted for comprehensive calibration of the model parameters, and then for validation of the model under 3D PSAR in any arbitrary direction. These comparisons highlight the model's capability in simulating the behavior of granular soil under 3D stress paths.

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Section: Model Formulation Unifying the Effects Of Principal Stress Vsupporting

confidence: 74%

Section: Model Performance For Laboratory Tests On Toyoura Sandmentioning

confidence: 95%

Three‐dimensional anisotropic plasticity model for sand subjected to principal stress value change and axes rotation

Xue

Pan

et al. 2020

Num Anal Meth Geomechanics

Self Cite

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“…Figs. 2(b and g) also clearly exhibit the anisotropy in both peak shear strength and shear modulus for samples with different initial bedding plane angles, which has been studied in detail in existing literature (Pietruszczak and Mroz 2000;Fu and Dafalias 2011;Cao et al 2017). At ε p q of 0.5, the deviatoric stress ratios of the eight samples evolve toward the same value, and the volumetric strains in Figs.…”

Section: Stress Strain and Dilatancy Ratiomentioning

confidence: 59%

Dependency of Dilatancy Ratio on Fabric Anisotropy in Granular Materials

2019

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The relationship between dilatancy and anisotropy is a fundamental aspect of anisotropic behavior of granular materials. Existing test data directly investigating this relationship are scarce and conflicting. Discrete element biaxial and triaxial numerical tests on idealized granular materials in both two-dimensional (2D) and three-dimensional (3D) are conducted in this study to acquire high quality stress, strain, dilatancy, and fabric data for various anisotropic samples, which are utilized to analyze the dependency of dilatancy ratio on fabric anisotropy. The test results indicate that the dilatancy ratio is not only dependent on the initial fabric anisotropy, but is also influenced by the evolution of fabric, especially the contact normal fabric. At low deviatoric stress ratio under biaxial and triaxial loading, difference in initial fabric anisotropy of granular materials can lead to distinctly different dilatancy ratios. As loading continues, the deviatoric stress ratio, void ratio, and fabric of granular materials evolve toward the unique critical state, causing the dilatancy ratio to converge irrespective of its initial value. The anisotropic critical state theory (ACST) is shown to be capable of providing a framework for quantitative mathematical depiction of the dependency of dilatancy ratio on fabric anisotropy.

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“…The classical isotropic failure criteria was generalized to anisotropic criteria by Tian and Yao (2017) using an anisotropic transformed stress method. Cao et al (2016) extended the L-D criterion to be an anisotropic L-D criterion by introducing a strength variable Λ related to stress tensor and the orientation of bedding plane and the obtained formula can also generalized the isotropic M-C and M-N criterion to become anisotropic. In addition, there are also various cross-isotropic strength criteria for geomaterials to characterize the stress-strain-strength anisotropy by introducing variables that include the information of material fabric and external loading into classical isotropic strength criteria.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Strength of Granular Material Considering Fabric Evolution

Liu

Zhang²,

Wang

et al. 2019

Lat. Am. j. solids struct.

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The effect of fabric anisotropy on strength has not been considered in most strength criterions for granular material. Some criterions can describe the variation of material strength with stress-induced anisotropy, but micro-mechanism and physical meanings are undefined. Some criterions consider the effect of fabric anisotropy, but the evolution of fabric is ignored during loading by assuming a constant fabric tensor. Based on strength mechanical characteristics of granular material, in this paper, the relationship between macro stress and micro contact force of granular material is derived by micromechanics. Then, the concept of true stress tensor is proposed. An anisotropic strength criterion of granular material considering fabric evolution is established and its applicability is validated by comparing with test results for different granular materials. The analysis results indicate that the proposed anisotropic criterion can be utilized to describe the strength feature of anisotropic granular materials, which gives a way for the cause analysis of the strength of granular materials from the perspective of Microscopic mechanism.

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Formulation of Anisotropic Strength Criteria for Cohesionless Granular Materials

Cited by 14 publications

References 31 publications

Three‐dimensional anisotropic plasticity model for sand subjected to principal stress value change and axes rotation

Three‐dimensional anisotropic plasticity model for sand subjected to principal stress value change and axes rotation

Dependency of Dilatancy Ratio on Fabric Anisotropy in Granular Materials

Anisotropic Strength of Granular Material Considering Fabric Evolution

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