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

以上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，在本研究的最终报告中进行了总结。术语“粗”指的是颗粒具有相当大的代表性尺寸，与它们的边界尺寸和合成树脂片的尺寸相比，这些尺寸是不可忽视的，例如，合成树脂片与颗粒混合以增强其强度。研究者共研究了10个课题，包括与人工和/或天然斜坡、铁路道砟、不同粒度分布的天然颗粒土沉积物等颗粒结构相关的静态和动态问题。研究人员还强调了开发可视化和模拟晶粒行为的新方法，因为颗粒之间的键相对较弱或没有键的颗粒材料永远不会表现得像连续介质。LAT（激光辅助断层扫描）是一种新方法，通过使用玻璃颗粒、与玻璃具有相同折射率的液体和强激光片，可以清楚地看到所有颗粒的形状和运动以及它们的组合。数值模拟方法DEM（离散元法）也被用于研究颗粒-颗粒相互作用及其对颗粒整体行为的影响。

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.