Exploring the micro-to-macro response of granular soils with real particle shapes via μCT-aided DEM analyses

Yang Li, M. Otsubo, Vasileios Angelidakis, R. Kuwano, S. Nadimi
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Abstract

This contribution provides high fidelity images of real granular materials with the aid of X-ray micro computed tomography (μCT), and employs a multi-sphere representation to reconstruct non-spherical particles. Through the discrete element method (DEM) simulations on granular samples composed of these non-spherical clumps, the effect of particle shape on the macroscopic mechanical response and microscopic soil fabric evolution is examined for soil assemblies under triaxial compression. Simulation results indicate that materials with more irregular particles tend to show higher shear resistance in both peak and critical states, while exhibiting higher void ratio under isotropic loading conditions and in the critical state. The proposed critical state parameters for describing the sensitivity of the mean coordination number to confining pressures are larger as particles become more irregular. At a microscopic level of observation, directional and scalar parameters of particle contacts are sensitive to predefined particle asperities. More irregular materials appear to exhibit higher fabric anisotropy regarding particle orientation in the critical state, while branch vector is affected by both contact modes and particle shape. The critical stress ratio from the simulation results is validated by comparing with experimental results, and further found to be linearly linked to the shape-weighted fabric anisotropy indices.
通过 μCT 辅助 DEM 分析探索具有真实颗粒形状的粒状土的微观到宏观响应
这篇论文借助 X 射线显微计算机断层扫描 (μCT),提供了真实颗粒材料的高保真图像,并采用多球体表示法重建非球形颗粒。通过对由这些非球形团块组成的颗粒样本进行离散元法(DEM)模拟,研究了颗粒形状对三轴向压缩下土壤组合的宏观力学响应和微观土壤结构演变的影响。模拟结果表明,含有更多不规则颗粒的材料在峰值和临界状态下往往表现出更高的抗剪性,同时在各向同性加载条件下和临界状态下表现出更高的空隙率。随着颗粒变得越来越不规则,用于描述平均配位数对约束压力敏感性的临界状态参数也越来越大。在微观观察层面上,颗粒接触的方向和标量参数对预定义的颗粒尖角很敏感。在临界状态下,更不规则的材料似乎在颗粒方向上表现出更高的结构各向异性,而分支矢量则同时受到接触模式和颗粒形状的影响。模拟结果中的临界应力比通过与实验结果的比较得到了验证,并进一步发现它与形状加权织物各向异性指数呈线性关系。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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