Development of shear device for large deformation of sand

砂土大变形剪切装置的研制

基本信息

批准号：
07555444
负责人：
TOWHATA Ikuo
金额：
$ 1.47万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555444/
关键词：
shear sand shear band microscope dilatancy large deformation 微視的観察定常状態

项目摘要

A new shear device for sand was developed which can study the granular movement of sand particles prior to and after the peak strength and during the state of residual strength.The shear device houses a specimen which measure 5^<**>5^<**>10cm^3in size. A vacuum pressure is introduced into the specimen in order to produce an effective confining pressure. This measure makes pressure cell unnecessary and enables a microscope to directly approach the specimen. The microscopic observation of granular movement is made further easier by covering one of the side faces of the specimen with a transparent acryl plate. The microscope employed in the present study has CCD transducers of digital type which make it possible to analyze the observed data by a computer.The present research revealed the following issues. Firstly, granular movement prior to the peak strength consists of falling of grains into adjacent large voids. This phenomenon occurs more or less uniformly in the specimen. In contrast, after the peak strength, shear movement of grains is concentrated in a narrow domain which is often called a shear band. The width of the shear band is approximately 10 times the grain's diameter. Both shear and rotational movements are significant in the shear band. In particular, the rotational movement was found to be irregular, occurring in both positive and negative directions. The dilatant motion was also found more important in the shear band than outside of it.

开发了一种新的沙子剪切装置，可以研究峰值强度和残余强度状态之前和之后的沙子颗粒运动。剪切装置容纳了一个标本，该样品是5^<**> 5^<*的标本。 *> 10cm^3英寸大小。为了产生有效的限制压力，将真空压引入样品中。该措施使压力单元不必要，并使显微镜能够直接接近样品。通过用透明的丙烯板覆盖样品的一个侧面之一，使颗粒运动的显微镜观察更加容易。本研究中使用的显微镜具有数字类型的CCD传感器，这使得通过计算机分析观察到的数据成为可能。当前的研究揭示了以下问题。首先，峰值强度之前的颗粒运动包括将晶粒掉落到相邻的大空隙中。这种现象在样品中或多或少均匀地发生。相反，在峰值强度之后，晶粒的剪切运动集中在一个通常称为剪切带的狭窄域中。剪切带的宽度约为谷物直径的10倍。剪切和旋转运动在剪切带中都很重要。特别是，发现旋转运动是不规则的，发生在正方向和负方向上。在剪切带中还发现膨胀运动比外部更重要。