Macroscopic and microscopic behaviors of binary mixtures of different particle shapes and particle sizes

Ng, Tang‐Tat; Zhou, Wei; Ma, Gang; Chang, Xiaolin

doi:10.1016/j.ijsolstr.2017.11.011

Cited by 52 publications

(17 citation statements)

References 25 publications

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“…This means that the grain shape has noteworthy influence on the value of minimum void ratio, but not on the triangle rule of relationship between void ratio and fine content, which is consistent with the research results in Ref. [29] and in those of Chang et al [30].…”

Section: Geofluidssupporting

confidence: 89%

“…In the research of natural and crushed sands, the idea was proposed that the macroscale behaviour of the soil mass such as packing density, stiffness, and strength can affect grain shape [26]. Ng et al [29] used the discrete element method for describing the relationship between void ratio and fine contents and proved that the grain shape factor has an influence on the initial modulus but not on the relationship between void ratio and fine content. However, grain shape has a noteworthy influence on the value of the minimum void ratio, which is generally lower for more spherical grains and higher for less spherical (or more angular) grains [30].…”

Section: Introductionmentioning

confidence: 99%

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Minimum Void Ratio Model Established from Tailings and Determination of Optimal Void Ratio

Liang

et al. 2021

Geofluids

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Minimum void ratio of tailings and its value change with fine content and are key design parameters for tailing consolidation and seepage stability. Based on the distribution of tailing grains with the sedimentary beach, we establish a minimum void ratio model for tailing grain in binary size, which requires only two parameters ( ε and ω ). Calibrations of the model using 168 groups of tests (22 kinds of grain size ratios with 7-9 kinds of fine contents) show two parameters that are fitting for power function, and the exponent values increase with the dominant grain size expanded. Besides, the exponent values are related to the equivalent grain size ratio, dominant grain size, and shape characteristics. The minimum void ratios with fine content are predicted under the derived model. Good agreement was obtained between the predictions and measurements, and the average discrepancies are less than 10%. And optimal void ratio and optimal fine content can be predicted, and the values are in good agreement with the experimental ones. Furthermore, based on the predicted optimal void ratio, the exponential relationship between the optimal void ratio and the equivalent grain size ratio may have no influence on the derived dominant grain size and shape characteristics. For tailings, further work is needed to verify if the derived exponential relationship between the optimal void ratio and the equivalent grain size ratio is valid.

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Section: Geofluidssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Minimum Void Ratio Model Established from Tailings and Determination of Optimal Void Ratio

Liang

et al. 2021

Geofluids

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“…In this case, the structure of gap‐graded soils (both in artificial or natural systems) may be assumed to be isotropic in a statistical point of view. As noted in previous studies, 30–32 this type of composites has isotropic macroscopic mechanical properties. Following the theory of elastoplasticity, the incremental strain is composed of an elastic part and a plastic part:

d ε_{i j} = d ε_{i j}^{e} + d ε_{i j}^{p}

d ε_{i j m} = d ε_{i j m}^{e} + d ε_{i j m}^{p}

where

ε_{i j}

and

ε_{i j m}

are the overall strain tensor of gap‐graded soils and the strain tensor of fine granular matrix, respectively;

d ε_{i j}^{e}

(

d ε_{i j m}^{e}

) and

d ε_{i j}^{p}

(

d ε_{i j m}^{p}

) are the corresponding elastic and plastic parts.…”

Section: Volume‐average Approachsupporting

confidence: 58%

A homogenization‐based state‐dependent model for gap‐graded granular materials with fine‐dominated structure

Shi

Zhao

Gao

2021

Num Anal Meth Geomechanics

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Gap‐graded granular soils are common natural soils composed of cohesionless granular matrix and rock aggregates. Since they are widely used as construction materials worldwide, their deformation behavior is crucial for the design of civil infrastructures. There have been rare constitutive models reported for gap‐graded granular soils in the literature. This study presents a homogenization‐based state‐dependent model within the elastoplastic framework. The model features a homogenization equation with a structure parameter and a novel state‐dependent dilatancy function to describe the behavior of granular matrix. Simulations of the model reveals that the initial stiffness and peak shear strength of gap‐graded soils rely on both the coarse fraction and the initial density of granular matrix. The structure parameter is related to the internal structure of gap‐graded soils, and it varies with the particle shape, and particle size distribution of rock aggregates. A higher value of the structure parameter indicates a more distinct coarse fraction effect of rock aggregates, that is, higher initial stiffness, higher peak shear strength, and higher residual shear strength. For a given coarse fraction, the critical states can be well fitted by a straight line through the origin, and the critical state strength parameter Mm increases with the rising rock fraction. A practical method is further proposed for the critical state line of gap‐graded granular soils in e‐p′ compression plane. The proposed model is validated by using experimental data from the literature, including the soils with various densities of sand matrix, different particle size, and particle size distribution of rock aggregates. Comparison between measured data and model predictions indicates that the proposed model can well reproduce the stress‐strain relationship and volumetric deformation behavior of sand‐gravel mixtures and soil‐rock mixtures.

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“…However, along with grain size, the strength properties of the granular media are strongly linked to the shape of grains. It has been shown in both numerical and experimental studies that grain shape has a nontrivial effect upon packing and shear properties of granular materials [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. For instance, the grains presenting the more angular shapes (in opposition to rounded) do not show the highest shear strengths as one could expect.…”

Section: Introductionmentioning

confidence: 99%

Microstructural analysis of sheared polydisperse polyhedral grains

2020

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This article presents an analysis of the shear strength of numerical samples composed of polyhedra presenting a grain size dispersion. Previous numerical studies using, for instance, disks, polygons, and spheres, have consistently shown that microstructural properties linked to the fabric and force transmission allow granular media to exhibit a constant shear resistance although packing fraction can dramatically change as a broader grain-size distribution is considered. To have a complete picture of such behavior, we developed a set of numerical experiments in the frame of the discrete element method to test the shear strength of polydisperse samples composed of polyhedral grains. Although the contact networks and force transmission are quite more complex for such generalized grain shape, we can verify that the shear strength independence still holds up for 3D regular polyhedra. We make a particular focus upon the role of different contact types in the assemblies and their relative contributions to the granular connectivity and sample strength. The invariance of shear strength at the macroscopic scale results deeply linked to fine compensations at the microstructural level involving geometrical and force anisotropies of the assembly.

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Macroscopic and microscopic behaviors of binary mixtures of different particle shapes and particle sizes

Cited by 52 publications

References 25 publications

Minimum Void Ratio Model Established from Tailings and Determination of Optimal Void Ratio

Minimum Void Ratio Model Established from Tailings and Determination of Optimal Void Ratio

A homogenization‐based state‐dependent model for gap‐graded granular materials with fine‐dominated structure

Microstructural analysis of sheared polydisperse polyhedral grains

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