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Shear behaviours of cohesionless mixed soils using the DEM: The influence of coarse particle shape
Particuology ( IF 3.5 ) Pub Date : 2020-08-03 , DOI: 10.1016/j.partic.2020.07.002
Yangui Zhu , Jian Gong , Zhihong Nie

The coarse particles in mixed soils can be cobbles or gravels, with the main difference being their roundness (an indicator describing particle shape characteristics at an intermediate scale). The influence of coarse particle shape (i.e., roundness) on the macroscopic and microscopic shear behaviours of cohesionless mixed soils with various fines contents (FCs) was investigated via the discrete element method in this study. The shapes of coarse particles were formed using the rotation-invariant spherical harmonic method proposed by previous investigators. An equation was proposed to predict the initial void ratios of samples in this study. A decrease in the roundness of coarse particles can increase the peak friction angle (FC  40%) and critical friction angle (FC  30%). As the roundness of coarse particles decreases, the peak dilatancy angle initially increases and then decreases (FC  20%). Furthermore, it was found that the roundness of coarse particles hardly affects the classification of cohesionless mixed soils, as determined by probing the percentage contributions of coarse–coarse, coarse–fine, and fine–fine contacts. When cohesionless mixed soils change from an underfilled structure to an interactive-underfilled structure at the critical state, the main forms of coarse–coarse contacts were discovered. Additionally, the force-fabric anisotropy mechanisms of the influences of the roundness and rolling resistance coefficient of coarse particles on the shear strengths of cohesionless mixed soils were found to be different.



中文翻译:

使用DEM的无粘性混合土的剪切行为:粗颗粒形状的影响

混合土壤中的粗颗粒可以是鹅卵石或砾石,主要区别在于它们的圆度(指示中等规模颗粒形状特征的指标)。通过离散元方法研究了粗颗粒形状(即圆度)对不同细度含量(FCs)的无粘性混合土宏观和微观剪切行为的影响。粗颗粒的形状是使用先前研究者提出的旋转不变球谐方法形成的。在本研究中,提出了一个方程来预测样品的初始空隙率。在粗颗粒的圆度的降低可以增加峰值摩擦角(FC   40%)和临界摩擦角(FC   30%)。作为粗颗粒的圆度减小,峰胀角最初增大,然后减小(FC   20%)。此外,发现粗颗粒的圆度几乎不会影响无粘性混合土的分类,这是通过探查粗-粗,粗-细和细-细接触的百分比贡献来确定的。当无粘性混合土在临界状态下从底部填充结构变为交互式底部填充结构时,发现了粗-粗接触的主要形式。此外,还发现力-纤维各向异性机制对粗糙颗粒的圆度和滚动阻力系数对无粘性混合土抗剪强度的影响是不同的。

更新日期:2020-08-03
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