Investigation of influence of particle characteristics on the non‐coaxiality of anisotropic granular materials using DEM |
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| Authors: | Mingjing Jiang Jun Sima Liqing Li Chuangbin Zhou Liang Cui |
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| Institution: | 1. Department of Geotechnical Engineering, Tongji University, Shanghai, China;2. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai, China;3. School of Civil Engineering, Wuhan University, Wuhan, Hubei, China;4. Henan Transportation Research Institute Co. Ltd, Zhengzhou Henan, China;5. School of Water Conservancy and Hydropower Engineering, Wuhan University, Wuhan, Hubei, China;6. Department of Civil and Environmental Engineering, University of Surrey, Guildford, Surrey, U.K. |
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| Abstract: | As a result of deposition process and particle characteristics, granular materials can be inherently anisotropic. Many researchers have strongly suggested that the inherent anisotropy is the main reason for the deformation non‐coaxiality of granular materials. However, their relationships are not unanimous because of the limited understanding of the non‐coaxial micro‐mechanism. In this study, we investigated the influence of inherent anisotropy on the non‐coaxial angle using the discrete element method. Firstly, we developed a new discrete element method approach using rough elliptic particles and proposed a novel method to produce anisotropic specimens. Secondly, the effects of initial specimen density and particle characteristics, such as particle aspect ratio A m, rolling resistance coefficient β , and bedding plane orientation δ , were examined by a series of biaxial tests and rotational principal axes tests. Findings from the numerical simulations are summarized as follows: (1) the peak internal friction angle ? p and the non‐coaxial angle i both increase with the initial density, A m and β , and they both increase initially and then decrease with δ in the range of 0–90°; (2) among the particle characteristics, the influence of A m is the most significant; and (3) for anisotropic specimens, the non‐coaxial angle can be calculated using the double slip and rotation rate model. Then, an empirical formula was proposed based on the simulation results to depict the relationship between the non‐coaxial angle and the particle characteristics. Finally, the particle‐scale mechanism of non‐coaxiality for granular materials was discussed from the perspective of energy dissipation. Copyright © 2016 John Wiley & Sons, Ltd. |
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| Keywords: | granular materials non‐coaxiality inherent anisotropy particle characteristics discrete element method energy dissipation rate |
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