Exploring the effects of particle shape and content of fines on the shear behavior of sand-fines mixtures via the DEM

Gong, Jian; Nie, Zhihong; Zhu, Yangui; Liang, Zhengyu; Wang, Xiang

doi:10.1016/j.compgeo.2018.10.021

Cited by 163 publications

(48 citation statements)

References 57 publications

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“…Comparing the results of the maximum damping ratio with the different gravel shapes in Figure 16, it can be observed that CGMr has a larger maximum damping ratio than CGMa when the gravel content is over 30%. Combined with Sun's results [16,17,35], the particles with angular shape tend to limit dislocation or rotation in CGMs, which relatively reduced the consumption of the shear wave energy and shows a smaller damping ratio under relatively large shear strain. In addition, with the increase of confining pressure, the maximum damping ratio reduces nonlinearly, where a similar tendency of the confining pressure to the maximum damping ratio of soil has been concluded by Lin et al [6,13,45], and the corresponding causes focus on the reduction of the void ratio and the increase of relative density.…”

Section: Maximum Damping Ratiomentioning

confidence: 54%

“…Compactness degree, density, and compacting power usually act as the control parameters in specimen preparation [14,25,29,[33][34][35]. In this article, for better comparing the indoor tests with in-site engineering construction, the same compacting power (160 J, mass of compact hammer is 2 kg, g is recognized as 10 N/kg, height of compact hammer is 0.4 m, 20 times with the compacting-sample device of each layer) was used in specimen preparation.…”

Section: Preparation For Specimenmentioning

confidence: 99%

“…The reason for the greater dynamic shear modulus of CGMr under lower shear strain (<10 −5 ) is because of the better compaction characteristic of CGMr under the same compaction work (shown in Figure 11) and the better completion in the gravel's edges (shown in Figure 3) [16,17,20,35]. The lower reduction tendency of the dynamic shear modulus with shear strain in CGMa can be explained by the better interlock effect between angular gravels when the dynamic shear strain appears in the CGM [2,17].…”

Section: Dynamic Shear Modulusmentioning

confidence: 99%

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Characterization of the Dynamic Properties of Clay–Gravel Mixtures at Low Strain Level

et al. 2020

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In order to support the dynamic design of subgrade filling engineering, an experiment on the dynamic shear modulus (G) and damping ratio (D) of clay-gravel mixtures (CGMs) was carried out. Forty-two groups of resonant column tests were conducted to explore the effects of gravel content (0%, 10%, 20%, 30%, 40%, 50%, and 60%, which was the mass ratio of gravel to clay), gravel shape (round and angular gravels), and confining pressure (100, 200, and 300 kPa) on the dynamic shear modulus, and damping ratio of CGMs under the same compacting power. The test results showed that, with the increase of gravel content, the maximum dynamic shear modulus of CGMs increases, the referent shear strain increases linearly, and the minimum and maximum damping ratios decrease gradually. In CGMs with round gravels, the maximum dynamic shear modulus and the maximum damping ratio are greater, and the referent shear strain and the minimum damping ratio are smaller, compared to those with angular gravels. With the increase of confining pressure, the maximum dynamic shear modulus and the referent shear strain increase nonlinearly, while the minimum and maximum damping ratios decrease nonlinearly. The predicting equation for the dynamic shear modulus and the damping ratio of CGMs when considering confining pressure, gravel content, and shape was established. The results of this research may put forward a solid foundation for engineering design considering low-strain-level mechanical performance.

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Section: Maximum Damping Ratiomentioning

confidence: 54%

Section: Preparation For Specimenmentioning

confidence: 99%

Section: Dynamic Shear Modulusmentioning

confidence: 99%

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Characterization of the Dynamic Properties of Clay–Gravel Mixtures at Low Strain Level

et al. 2020

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“…Particle shape representation and reconstruction are becoming increasingly important for numerical investigations of particle morphology and its effects on micro-macro mechanical behavior [1,[30][31][32]. Clumps, clusters and polyhedrons have typically been used in discrete element modeling to represent a realistic shape, along with developed overlapping or skeletonization algorithms (e.g.…”

Section: Particle Shape Reconstructionmentioning

confidence: 99%

Internal rolling method for particle shape evaluation and reconstruction

2020

PLoS ONE

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A concise and robust method for 2D particle shape evaluation and reconstruction is proposed using the concept of the internal rolling of covering discs within the outline of a particle. By downscaling the covering disc size for capturing multiscale features, the calculation of the Euclidean distance can effectively yield three indices for sphericity, roundness and roughness. The geometric-based evaluations of particle morphology are dimensionless and precisely distinguishable between shapes after calibration and validation against constructed particles and natural sands. A sphericity-roundness diagram is provided to visualize the particle shape characterization, and a probabilistic density surface in the sphericity-roundness diagram is then proposed to statistically represent the distributions of the particle shapes. The concept of internal rolling is also utilized for particle shape reconstruction using a limited number of balls to replicate the indices of sphericity, roundness and roundness characteristic curve. The probabilistic density surface is duplicated for statistical particle shape reconstruction, which provides an effective approach for numerical investigations of the relationships between particle shapes and mechanical behavior. The effect of image quality on 2D shape evaluation is also examined by using a minimum area per particle, and the proposed method is intuitively extendable to 3D measurements using rolling covering spheres.

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“…Matsuoka [11] studied the evolution law of the particle contact angle during the direct shear process of aluminium rods through a photoelastic test to derive the stress-dilatancy relation equation. Since 1979, with the introduction of the discrete element method (DEM) [12], the DEM has gradually become a major tool for studying the microscale rules of granular matter systems, and the DEM has previously been demonstrated to be able to reproduce certain key features of granular materials [13][14][15][16]. Matuttis et al [17] studied the characteristics of the arch and force chain inside an accumulation body formed by spherical particles and polygonal particles by using DEM and found that the distribution characteristics of the arch and force chain inside the accumulation body formed by the two types of particles were not very different, but the accumulation history process, such as point-source-type pouring and the one-by-one accumulation of monolayer particles, has a great influence on the accumulation result and force chain distribution.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Study on the Contact Force and Force Chain Characteristics of Ore Particle Systems during Ore Drawing from a Single Drawpoint under the Influence of a Flexible Barrier

Chen

Qin

2020

Geofluids

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It is of great significance to carry out quantitative research on the contact force chain characteristics of ore particle systems during ore drawing to reveal the microscopic and mesoscopic characteristics of ore particle systems during implementation of the synchronous filling shrinkage stoping method. Based on the particle discrete element method, combined with the relevant knowledge of contact mechanics and statistical mechanics, microscopic properties of the ore particle system were studied quantitatively. (1) The probability distributions of the normal and tangential contact forces during ore drawing from a single drawpoint under a flexible barrier are similar, and both show exponential decay. (2) In the regions on both sides of the model, the ore particles will not be released because they are far from the drawpoint; there, the coordination number is stable, and the density of contact network is large. In the upper part of the drawpoint, ore particles flow, the coordination number fluctuates violently, and the density of contact network is small. (3) In the initial stage, the stress distribution of the ore particle system is uniform, and the strong force chain does not show obvious directivity. After that, the directions of the strong force chains in the ore particle system are inclined to the vertical direction, and the strong force chains mainly bear the load in the vertical direction. (4) In the initial stage of drawing, the normal contact force is mainly concentrated in the vertical direction. With the progression of drawing, the normal contact force at an angle of 30° to the horizontal direction increases gradually, and the number of the main direction of the average contact force distribution changes from one to three (the vertical direction and the direction with a ±30° angle to the horizontal direction).

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Exploring the effects of particle shape and content of fines on the shear behavior of sand-fines mixtures via the DEM

Cited by 163 publications

References 57 publications

Characterization of the Dynamic Properties of Clay–Gravel Mixtures at Low Strain Level

Characterization of the Dynamic Properties of Clay–Gravel Mixtures at Low Strain Level

Internal rolling method for particle shape evaluation and reconstruction

Quantitative Study on the Contact Force and Force Chain Characteristics of Ore Particle Systems during Ore Drawing from a Single Drawpoint under the Influence of a Flexible Barrier

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