粉质土直接剪切变形过程中的组构特征

采用直接剪切试验中的剪切带土样,利用电子探针进行定向表面的微观扫描,研究了粉质土在剪切变形过程中的组构特征.发展和完善了土的微观结构的实验方法,编制了实用的土颗粒图象处理软件和组构量概率统计程序,建立了各定向组构量的概率模型,提出角度组构量应该用二阶张量或四阶张量描述,给出了剪切变形过程中各组构量的统计分布变化的一般趋势.

Fabric characteristics of silty soil during direct shearing deformation

In order to establish microscopic mechanical model of soil,samples from shearing band in direct shear test of the silty soil in Shanghai are collected,and the fabric characteritics are studied during direct shearing deformation by scanning directional microscopic surfaces with an electric probe.The experimental methodology on microstructure of soil is improved,and a practical software for processing images of soil particles and a probabilistic statistical program for calculating fabric quantities are developed.The probability models for directional fabric quantities are established,and the distribution changes of fabric quantities are analyzed as the shearing deformation advances.It is suggested that normal or beta distribution is not proper to describe the probabilistic statistical model of soil's directional fabric quantities while tensor distribution of the second rank or fourth rank is rational instead. When shearing displacement increases,the orientation of partical long axis changes and comes to close to the macroscopic shear direction.