Macroscopic and microscopic behaviors of granular materials under proportional strain path: a DEM study

Zhou, Wei; Liu, J.; Ma, Gang; Yuan, Wei; Chang, Xiaolin

doi:10.1002/nag.2537

Cited by 31 publications

(3 citation statements)

References 62 publications

(82 reference statements)

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“…A simple contact model consisting of a linear spring in parallel with a viscous damping element proposed in the pioneering work by Cundall and Strack [4] is still very popular in DEM simulations [3,7,16]. A nonlinear elastic interaction is included in the contact models based on the Hertz theory [5,11,25].…”

Section: Introductionmentioning

confidence: 99%

Numerical and experimental investigation of an elastoplastic contact model for spherical discrete elements

et al. 2018

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A contact model for the normal interaction between elastoplastic spherical discrete elements has been investigated in the present paper. The Walton-Braun model with linear loading and unloading has been revisited. The main objectives of the research have been to validate the applicability of the linear loading and unloading models and estimate the loading and unloading stiffness parameters. The investigation has combined experimental tests and finite element simulations. Both experimental and numerical results have proved that the interaction between the spheres subjected to a contact pressure inducing a plastic deformation can be approximated by a linear relationship in quite a large range of elastoplastic deformation. Similarly, the linear model has been shown to be suitable for the unloading. It has been demonstrated that the Storåkers model provides a good evaluation of the loading stiffness for the elastoplastic contact and the unloading stiffness can be assumed as varying linearly with the deformation of the contacting spheres. The unloading stiffness can be expressed in a convenient way as a function of the Young's modulus and certain scaling factor dependent on the dimensionless parameter defining the level of the sphere deformation.

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Section: Introductionmentioning

confidence: 99%

Numerical and experimental investigation of an elastoplastic contact model for spherical discrete elements

et al. 2018

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“…It is less discussed for fabrics with non-circular and non-spherical particles. Whereas particle rotation is the main style of particle movement, the effect of particle shape on particle rotation can be used to justify the rolling resistance parameters introduced to counterbalance the spherical simplification of the grains geometry in DEM simulations [21][22][23], and other particle shapes excepting regular polygonal particles that have been researched can be used to compare with circular particles [21]. Thus, particle rotation varying with particle shape is worth discussing.…”

Section: Introductionmentioning

confidence: 99%

Effect of particle shape on micro- and mesostructure evolution of granular assemblies under biaxial loading conditions

Tian

Liu

2018

Comptes Rendus. Mécanique

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Discrete element method (DEM) numerical biaxial tests on samples with different particle shapes are performed to investigate how the multiscale evolves with varying particle shape. The samples used in such simulations are composed of circular, square, and elongated particles, respectively. For the numerical results, analyses are conducted in terms of microscopic evolution, i.e. particle rotation and evolution of fabric, and mesoscopic evolution, i.e. the evolution of loops and improved clustering coefficient. At the microscale, the mean particle rotation of circular particles is remarkably larger than those of square and elongated particles, and the shear band localization phenomenon is more obvious when the aspect ratio (AR) decreases. Considering the fabric evolving with particle shape, the value of anisotropy gradually increases when particle shape becomes irregular, and contacts of circular particles are pronouncedly less than those of irregular particles from the coordination number and curves of degree distribution. At the mesoscale, when the particle relationship is considered, the isotropic particles (i.e. circular and square particles) have similar evolutions of loops and modified clustering coefficient, whereas the elongated particles have remarkable three loops and modified clustering coefficient, which are both larger than those of isotropic particles.

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“…Limited by equipment, it is difficult to achieve accurate control of the strain path of the specimen during the experimental study. But numerical simulation can avoid these problems and several authors have used the discrete element method to study the behavior of granular soils under different loading conditions (Gu et al, 2014a;Gu et al, 2014b;Guo and Zhao, 2016;Zhou et al, 2016). Therefore, in this paper, the discrete element method was used to simulate a series of proportional strain tests of sandy soil with different initial void ratio e and different strain ratio α .…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of diffuse instability in sandy soil using discrete element method under proportional strain path loading

Meng

Liu

Han

et al. 2018

Lat. Am. j. solids struct.

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The Loose sandy soil can manifest static liquefaction phenomenon under undrained condition, in which the onset of instability is within the failure line, and there is no obvious shear band. This type of failure mode, very different from localized instability that occurs in dense sand, is called the diffuse instability. In this paper, a series of proportional strain tests and fully drained tests under different initial void ratio were simulated using the discrete element method. The influence of strain increment ratio and the initial void ratio affecting the instability of sandy soil were discussed in detail. The development mechanism of pore water pressure in proportional strain tests was analyzed by comparing with the volumetric curve of fully drained test. Finally, a unified mechanism of diffuse instability of sandy soil in proportional strain tests was explained. Numerical results indicate that the strain increment ratio and the initial void ratio work together affecting the instability of specimen. The occurrence of diffuse instability is the result of effective stress reduction due to the development of pore water pressure, which depends on the difference of volumetric strain between fully drained tests and proportional strain tests. The increment of pore water pressure is determined by the difference of strain increment ratio, which can be used as an index to reflect the liquefaction potential of sandy soil.

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Macroscopic and microscopic behaviors of granular materials under proportional strain path: a DEM study

Cited by 31 publications

References 62 publications

Numerical and experimental investigation of an elastoplastic contact model for spherical discrete elements

Numerical and experimental investigation of an elastoplastic contact model for spherical discrete elements

Effect of particle shape on micro- and mesostructure evolution of granular assemblies under biaxial loading conditions

Numerical investigation of diffuse instability in sandy soil using discrete element method under proportional strain path loading

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