砂土单调剪切特性的非圆颗粒模拟

针对纯圆颗粒模拟的缺陷,利用颗粒流"团颗粒"方法开发了形状近似椭圆的"椭圆团颗粒",研究了颗粒形状变化对数值试样宏观剪切特性的影响及其细观机理;分析了加荷过程中平均接触数的变化规律以及颗粒形状对临界接触数的影响;对比了纯圆颗粒和椭圆团颗粒的不同颗粒旋转特性,并初步探讨其机理;分析了剪切过程中椭圆团颗粒试样的组构各向异性演化规律。结果表明,颗粒形状对试样的强度和变形特性具有重要影响,其在细观机理上与平均接触数有关;剪切荷载作用下椭圆团颗粒试样呈现明显的组构各向异性,颗粒长轴逐渐趋于水平定向,接触法向逐渐偏于加荷的大主应力方向。

Numerical simulation for behaviors of sand with non-circular particles under monotonic shear loading

Considering the limitations of circular particle simulation,the elliptical particle element was developed by using the clump logic in particle flow code.The effect of particle shape on the macro-mechanical behaviors of numerical samples under monotonic shear loading was studied,and the mechanism was explained microscopically.The evolution of average co-ordination number during the process of loading was particularly investigated,and the influence of particle shape on the critical average co-ordination number was also evaluated.The particle rotation property was compared between the elliptical particle samples and the circular particle samples,and the development of fabric anisotropy during loading was also analyzed.It was found that the strength and the deformation properties of numerical samples were obviously affected by the particle shape and the mechanism was microscopically related to the average co-ordination number.During the process of loading,there was a tendency of the long axes of elliptical particles to align in horizontal direction,and the contact normal gradually oriented in the direction of the major principal stress.