Microscopic study on stress-strain relation of granular materials

Liu, SiHong; Yao, Yao; Sun, Qiu; Li, Tiejun; Liu, MinZhi

doi:10.1007/s11434-009-0599-z

Cited by 6 publications

(3 citation statements)

References 17 publications

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“…At present, there are several ways to characterize the microstructures of granular materials, such as fabric tensor (Satake, 1982), coordination number, comprehensive structure potential (Xie and Qi, 1999) and particle contact angles (Liu et al, 2009). In our previous works, we preferred to use the particle contact angle, which is defined to be an angle of the connection line of two contacting circular particles' centers inclined to a certain base level, with a positive in counterclockwise direction, as indicated in Figure 4.…”

Section: Microstructures Of Granular Materialsmentioning

confidence: 99%

A yield function for granular materials based on microstructures

Liu

Wang

et al. 2015

Engineering Computations

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1998),"Strategic planning, risk-taking and reward systems for managers in multi-divisional companies -an empirical study"If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The purpose of this paper is to propose a new yield function for granular materials based on microstructures. Design/methodology/approach -A biaxial compression test on granular materials under different stress paths is numerically simulated by distinct element method. A microstructure parameter S that considers both the arrangement of granular particles and the inter-particle contact forces is proposed. The evolution of the microstructure parameter S under the simulated stress paths is analyzed, from which a yield function for granular materials is derived. The way of determining the two parameters involved in the yield function is proposed. Findings -The new yield function is calibrated using the test data of one sand and two rockfill materials. The shape of the new yield surface is similar to that of the Cam-clay model. Originality/value -The paper proposes a microstructure parameter S, which considers both the arrangement of granular particles and the inter-particle contact forces. From the evolution of S, a yield function for granular materials is derived. The proposed yield function has a simple structure and the parameters are easy to be determined, leading to a feasible realization of engineering application.

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Section: Microstructures Of Granular Materialsmentioning

confidence: 99%

A yield function for granular materials based on microstructures

Liu

Wang

et al. 2015

Engineering Computations

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“…Along the development of micromechanical model, the anisotropic degree of local stress‐dilatancy relationship is related to the orientation‐dependent second‐order tensor which refers to the fabric anisotropy 5,41,42 . It is important to note that, the internal structure of granular materials will reorganize under shearing due to the stochastic motion of particles, for example, sliding, rolling and contact opening 43–45 . For instance, Liu et al 45 .…”

Section: Introductionmentioning

confidence: 99%

“…5,41,42 It is important to note that, the internal structure of granular materials will reorganize under shearing due to the stochastic motion of particles, for example, sliding, rolling and contact opening. [43][44][45] For instance, Liu et al 45 proposed that the changes of granular microstructures during shearing attributes to the appearing of contacts along axial compression direction, the disappearing of contacts along confining direction as well as the change of particle contact angles of the steady contacts controlled by interparticle friction law. It suggests that the changes of contact distribution are closely related to the stress-dilatancy relationship of granular materials.…”

Section: Introductionmentioning

confidence: 99%

Micro‐mechanism of stress‐dilatancy anisotropy in granular materials: Affine and nonaffine deformation

Liu,

Wang

2024

Num Anal Meth Geomechanics

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The stress‐induced dilatancy anisotropy is an important kinematic response in granular materials and is very complex due to the stochastic motion of particles. In this study, the local stress‐dilatancy relationship is investigated referring to the local contact force and relative displacement in a certain contact direction. The micromechanism of this anisotropy is investigated from the view of affine and nonaffine approaches based on DEM simulation. Numerical results indicate that the local nonaffine dilatancy/contraction tendency is opposite with that of local affine deformation in macroscopic compression and extension direction, which mainly stems from the counteraction effect between the normal components of affine and nonaffine displacements. The local stress‐dilatancy of affine and nonaffine components is linear and orientation‐dependent, which results in the nonlinear character of macroscopic stress‐dilatancy. By establishing an analytical relation of stress‐dilatancy, the local affine/nonaffine dilatancy is decomposed into the component of stress‐induced dilatancy synchronized with the local stress anisotropy; and the component of stress‐induced dilatancy asynchronized with the local stress anisotropy. The former is related to the unchanged isotropic microstructure, and the latter attributes to the anisotropic microstructure. Besides, the contribution of nonsliding contacts to nonaffine dilatancy is larger than that of sliding contacts even for the case of relatively higher sliding ratio, which indicates that the heterogeneous deformation attributes not only to the friction dissipation, but to the blocked energy at micro contacts in granular materials.

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Systematic effect of particle roundness/angularity on macro- and microscopic behavior of granular materials

et al. 2023

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Roundness/angularity is a vital shape descriptor that significantly impacts the mechanical response of granular materials and is closely associated with many geotechnical problems, such as liquefaction, slope stability, and bearing capacity. In this study, a series of biaxial shearing tests are conducted on dual-size aluminum circular and hexagonal rod material. A novel image analysis technique is used to estimate particle kinematics. A discrete element model (DEM) of the biaxial shearing test is then developed and validated by comparing it with the complete experimental data set. To systematically investigate the effect of roundness/angularity on granular behavior, the DEM model is then used to simulate eight non-elongated convex polygonal-shaped particles. Macroscopically, it is observed that angular assemblies exhibit higher shear strengths and volumetric deformations, i.e., dilations. Moreover, a unique relationship is observed between the critical state stress ratio and particle roundness. Microscopically, the roundness shows a considerable effect on rotational behavior such that the absolute mean cumulative rotation at the same strain level increases with roundness. A decrease in roundness results in relatively stronger interlocking, restricting an individual particle’s free rotation. Furthermore, the particles inside the shear band exhibit significantly higher rotations and are always associated with low coordination numbers. Generally, the geometrical shape of a particle is found to have a dominant effect on rotational behavior than coordination number. Graphical Abstract

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Microscopic study on stress-strain relation of granular materials

Cited by 6 publications

References 17 publications

A yield function for granular materials based on microstructures

A yield function for granular materials based on microstructures

Micro‐mechanism of stress‐dilatancy anisotropy in granular materials: Affine and nonaffine deformation

Systematic effect of particle roundness/angularity on macro- and microscopic behavior of granular materials

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