Mathematical and Experimental Approaches for Evaluation of Dynamic and Static Stability of Granular Structures

本研究的最后报告总结了上述六位研究者为阐明粗颗粒材料的变形过程所做的所有尝试。术语“粗”是指颗粒具有相当大的代表性尺寸，与其边界尺寸和合成树脂片的尺寸相比，例如，与颗粒混合以提高其强度时，颗粒具有不可忽视的代表性尺寸。研究的10个课题包括人工和/或天然边坡、铁路道碴、天然颗粒土沉积物具有不同的颗粒尺寸分布。由于颗粒之间的结合力相对较弱或没有结合力的颗粒材料永远不会表现出行为，因此重点也放在开发可视化和模拟颗粒行为的新方法上就像一个连续的媒介。LAT（激光辅助断层扫描）是一种新的方法，它允许所有的颗粒形状和运动，以及在他们的集合体，以清晰地可视化使用玻璃颗粒，液体具有相同的折射率的玻璃和强烈的激光片。离散元法（DEM）的数值模拟方法，也被用来研究颗粒-颗粒的相互作用及其对颗粒体的整体行为的影响。

All atempts by the above six investigators to clarify deforming processes of coarse granular materials are summarized in the final report of this study.The terminology "coarse" means that grains have fairly large representative sizes that can not be ignored, when compared with dimensions of their boundaries and sizes of synthetic resin pieces, for example, that are mixed up with the grains to enhance their strengths. Total 10 subjects that the investigators have studied include both the static and dynamic problems related to such granular structures as artificial and/or natural slopes, ballast of railways, natural granular soil deposits with different grain size distributions.Stress was also put on developing new methodologies for visualizing and simulating the behaviors of grains because a granular material with relatively weak or no bonds among its grains never behaves like a continuous medium. LAT (Laser-Aided Tomography) is one of those new methods that allows all the grains shapes and motions as well within their assemblages to be clearly visualized by using glass grains, the liquid with the same refractive index as the glass and an intense laser-light sheet. A numerical simulation method, DEM (Discrete Element Method) was also used to examine grain-grain interaction and its effect on overall behavior of the granular mass.