基于离散元模拟的砂土三维临界状态特征研究
Discrete Simulation of Critical State Characteristics of Three-dimensional Granular Materials by DEM
蒋成龙 1许成顺 1焦爽 1王晓丽1
作者信息
- 1. 北京工业大学城市与工程安全减灾教育部重点实验室,北京 100124
- 折叠
摘要
对于在室内土工试验很难得到土体临界状态下的颗粒运动、局部孔隙比变化等特征的问题,基于离散元平台,构建了柔性边界条件下的不同初始物理状态的砂土试样的常规三轴数值模型,对不同初始孔隙比的砂土试样的剪切带的演化形成、试样的整体孔隙比和局部孔隙比的变化规律等细观特征进行对比.数值计算结果表明:相对密实的砂土在剪切过程中更容易形成剪切带;剪切带内部颗粒随着加载发生剧烈转动现象,局部颗粒的流动呈现紊流特征;非剪切带上颗粒转动不明显,流动呈现定向特性;不同初始孔隙比的砂土试样,其剪切带上的临界状态孔隙比和偏应力比与初始孔隙比无关,临界状态特征的组构张量不变量的稳定特性,说明其临界状态存在且唯一.
Abstract
To solve the problem that it is difficult to obtain the characteristics of particles motion trajectory and local void ratio change in the critical state of soil in laboratory tests.Several conventional triaxial numerical models of granular materials with different initial states under flexible boundary conditions was established by DEM to contrast the evaluation characteristics of shear bands and the differences in the overall void ratios and local void ratios of granular materials with different initial void ratios.The numerical results show that:The sand specimens with a larger initial void ratio are more likely to form shear bands in the loading process.The particles in the shear region rotate violently with the loading,and the flow of local particles is turbulent.The particles out of the shear zone rotation are not obvious,and the flow shows directional characteristics.For sand samples with different initial void ratios,the critical state void ratios on the shear band and the deviator stress ratio are independent of the initial void ratio,and the stable characteristics of the constitutive tensor invariants of the critical state characteristics indicate that the critical state exists and is unique.
关键词
砂土/临界状态/柔性边界/剪切带/速度矢量场/孔隙比的演化/组构张量Key words
granular material/critical state/flexible membrane condition/shear band/velocity field/evolution of the void ratio/fabric tensor引用本文复制引用
基金项目
国家自然科学基金优秀青年基金项目(51722801)
出版年
2024
NETL
NSTL
万方数据