权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Fundamental study on transition from quasi-static to rapid flow of granular materials

颗粒材料准静态向快速流动转变的基础研究

基本信息

批准号：
16360233
负责人：
ODA Masanobu
金额：
$ 7.36万
依托单位：
Saitama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16360233/
关键词：
Granular materials Mechanism of granular flow Shear zone Image analysis Numerical simulation 実験

项目摘要

Soil-related structures such as embankments and retaining walls are usually designed on stability analysis. To analyze the stability, soil engineers need a failure criterion of soils, and have done a lot of research works for it. However, failure of soil-related structures is repeated every year, and flowing soil debris causes a huge damage to the civil engineering structures and human lives. This fact implies that not only the failure criterions but also the flowing behavior after failure are very important to reduce such damage. Soil movement starts as quasi-static flow along a shear band, and the speed increases, as called rapid flow, if a certain condition (not understood yet) is satisfied. In order to understand the transition behavior from quasi-static to rapid flow, laboratory tests and numerical simulation tests are carried out, with special interest in the microscopic aspect of flow mechanism during quasi-static and rapid flow. The conclusion are summarized as follows:1)Two-di … More mensional flow of particle assembly is generated in a rotary shear cell, and individual particles are chased by means of high-speed camera and image analysis. Micro-behaviors of granular flow such as particle rotation, granular temperature, collision angle and velocity gradient profile are investigated to obtain a criterion distinguishing between quasi-static and rapid flow from a microscopic point of view.2)Three-dimensional micro-structure in a quasi-static flow domain is observed by means of micro-focus X-ray computed tomography. Based on the results, a new dilatancy model in a shear zone is proposed under strong support from numerical simulation of Distinct Element Method (DEM). A new methodology for quantitative representation of micro-structure is also proposed.3)DEM is applied to simulate numerically transition from quasi-static to rapid flow, and the results are compared with the ones of laboratory tests. It is found that DEM provides a reliable tool to simulate of whole range from quasi-static to rapid granular flow of granular materials. DEM is expanded, with success, so that the effect of water on granular flow can be taken into account. Less

与土壤有关的结构，如挡土墙和挡土墙，通常是根据稳定性分析设计的。为了分析土体的稳定性，岩土工程师们需要一个土体的破坏准则，并为此做了大量的研究工作，然而每年都有与土体相关的建筑物发生破坏，流动的土屑对土木工程结构和人类生命造成巨大的危害。这一事实意味着，不仅破坏准则，而且破坏后的流动行为是非常重要的，以减少这种损害。土壤运动开始时是沿剪切带沿着的准静态流动，如果满足一定的条件（尚不清楚），则速度增加，称为快速流动。为了了解准静态到快速流动的过渡行为，进行了实验室试验和数值模拟试验，特别关注准静态和快速流动期间流动机制的微观方面。主要结论如下：1）双向 ...更多信息在旋转剪切池中产生颗粒集合体的表面流动，并通过高速摄像和图像分析来追踪单个颗粒。通过对颗粒旋转、颗粒温度、碰撞角和速度梯度分布等微观行为的研究，从微观角度获得了准静态和快速流动的判别准则。2）利用微焦点X射线CT对准静态流动区域的三维微观结构进行了观察。在此基础上，在离散元数值模拟的有力支持下，提出了一种新的剪切带剪切变形模型。3）采用离散元法对准静态到快速流动的过渡过程进行了数值模拟，并与实验结果进行了比较。结果表明，离散元法为模拟颗粒物从准静态到快速流动的全过程提供了可靠的工具。成功地扩展了DEM，使水对颗粒流的影响得以考虑。少