| 单粒组密砂剪切带的直剪试验离散元数值分析 |
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| 引用本文： | 蒋明镜,王富周,朱合华.单粒组密砂剪切带的直剪试验离散元数值分析[J].岩土力学,2010,31(1):253-257. |
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| 作者姓名： | 蒋明镜 王富周 朱合华 |
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| 作者单位： | 1. 同济大学 地下建筑与工程系，上海 200092；2. 同济大学 岩土及地下工程教育部重点实验室，上海 200092 |
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| 基金项目： | 国家自然科学基金，国家自然科学基金 |
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| 摘 要： | 为分析砂土的剪切力学特性，采用离散元商业软件PFC2D对单粒组密砂在直剪试验中出现的剪切带进行了数值分析。改进传统的分条带观察方式，采用矩形格分割法观察试样内部不同区域的变形特性。对离散元商业软件进行了二次开发，实现了大小主应力及其应力主方向角的可视化，分析了试样内部的应力偏转情况。同时，以纯转动率和颗粒速度等微观变量为中心，观察了试样内部颗粒的运动状态，解析了直剪试验中砂土剪切带形成的微观机制。研究表明，直剪试验中应变局部化区域集中在剪切面附近的一个条带内。通过转动场和速度场的分析可知，剪切带宽度约为10～15倍的砂土平均粒径，带内颗粒转动明显，带边缘出现大的速度和转动变化梯度。对组构和接触力分布的分析可知，剪切过程中粒间接触点和接触力的主轴方向发生了相一致的偏转，偏转后的主轴方向为60°左右。
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| 关 键 词： | 离散元 剪切带 转动场 组构 |
| 收稿时间： | 2009-07-18 |
Shear band formation in ideal dense sand in direct shear test by discrete element analysis |
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| JIANG Ming-jing,WANG Fu-zhou,ZHU He-hua.Shear band formation in ideal dense sand in direct shear test by discrete element analysis[J].Rock and Soil Mechanics,2010,31(1):253-257. |
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| Authors: | JIANG Ming-jing WANG Fu-zhou ZHU He-hua |
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| Institution: | 1. Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China; 2. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092, China |
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| Abstract: | In order to analyze the shear behavior of sands, a numerical investigation was carried out on the shear band of ideal dense sand in direct shear test using PFC2D. The traditional band observation method is replaced by a new method , by which the sample is painted into square grid to observe sample deformation pattern. The discrete elements commercial software PFC2D is improved to visualize principal stresses and their inclinations in the sample. Averaged pure rotation rate(APR) and particle velocity are observed to describe the sample with aim to analyze the micro mechanism of the strain localization in dense sand. The study shows that in direct shear test, the strain is concentrated in a band near the shear plane, whose thickness is 10 to 15 times of d50. The particles in the shear band demonstrate significant rotation. Higher gradients are found in velocity and rotation fields on the edge of the shear band. The observation on the contact fabric and contact force shows that principal directions of contact points and contact forces rotate in the similar way with their inclination direction about 60° to the horizontal direction. |
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| Keywords: | discrete elements shear band APR fabric |
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