摘要
自然条件下,颗粒介质大多以非规则单元形态存在。非规则几何形态对颗粒介质的宏观力学性能有很大影响。针对颗粒单元的不同几何形态,采用团颗粒单元对离散介质的直剪试验过程进行了离散元数值计算,详细地讨论了颗粒形态对离散介质剪切强度的影响。该非规则颗粒由不同形态、不同数目、镶嵌尺寸、组合方位和颗粒大小的球形颗粒进行随机构造,其在局部与整体坐标之间的转动、力矩和方位关系通过4元素方法进行确定,基本球体颗粒之间的作用力采用具有Mohr-Coulomb摩擦定侓的Hertz-Mindlin非线性接触模型,并考虑了非线性法向粘滞力的影响。通过构造7种具有相同的质量概率分布的不同形态的团颗粒,在不同法向应力下,对团颗粒的直剪试验进行了离散元模拟,分析了不同形态颗粒的剪切强度。通过对不同形态颗粒介质剪切强度的数值分析,进一步揭示了非规则颗粒间的咬合互锁效应,为分析非规则颗粒的宏观动力特性提供了依据。
Granular materials exhibit irregular shapes under natural conditions,and the particle shape has great effects on its macro mechanical behaviors.Direct shear tests are simulated by using discrete element model(DEM) with clumps of spheres resembling the real shapes of granular materials,and the effects of different particle shapes on the shear strength are discussed.A clump is constructed by clumping spheres with different numbers,diameters,orientations and overlaps.The quaternion method is introduced to transform the rotation,the resultant force and the moment acting on a clump in global and local coordinates.The interactions between particles are described by Hertz-Mindlin contact model incorporated with the nonlinear normal viscous force and Mohr-Coulomb friction law.Seven different clumps with the same mass probability distribution are generated and used to simulate direct shear tests under different normal stresses.For each clump,the shear strength is analyzed.With the simulated results,it is shown that the interlocking among particles can be simulated well with the clumps of spheres.The presented model provides a foundation for analyzing the macro behaviors of irregularly shaped granular materials.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2009年第S1期225-230,249,共7页
Rock and Soil Mechanics
基金
国家自然科学基金资助项目(No.50808027
10772041)
教育部留学回国人员科研启动基金(No.2007-1108
2008-890)
关键词
离散介质
颗粒形态
剪切强度
直剪试验
离散元
discrete media
particle shape
shear strength
direct shear test
discrete element
