基于体视学原理砂土孔隙组构的图像分析

Image Analysis of Sand Void Fabric Based on Stereology Principle

摘要:

基于体视学原理定量描述孔隙组构的数学框架，采用归一化思想重新定义组构张量，提出了砂土孔隙组构描述的新方法.该方法用平面张量的第二不变量定义幅值参量来描述孔隙各向异性的大小，用其分量定义方向参量来描述各向异性方向，用这两个标量描述平面孔隙分布规律.采用多种图像处理技术消除砂样SEM图的一些干扰因素，优化得到清晰的二值化图像.砂样SEM图像分析表明：不同角度的平行测试线可以用于测量平均孔隙率，但无法测定其平面孔隙分布，环形测试线则可较好描述孔隙的空间分布规律.新方法用两个标量来描述平面孔隙分布，随孔隙空间几何关系变化，自然退化为现有张量的描述形式.图像分析验证了新方法描述的合理性.

Abstract:

Based on the theoretical framework of quantitative description for void fabric with the principle of stereology, the void fabric tensor redefined with normalized idea, and a novel description method of void fabric for sand was proposed. The porosity amplitude parameter defined by the second invariant of the plane tensor to describe the degree of anisotropy and the direction parameter defined by its component to describe its direction, the plane distribution of void fabric were described by these two scalars. The program with different image processing techniques that eliminate the confounding factors of analysis on scanning electron microscope(SEM) image of sand samples was developed to obtain a clear binary image with optimization methods. The SEM image analysis of sand sample showed that parallel test lines with different angles could measure the average porosity but could not measure the porosity distribution, while the circular test line could measure the plane distribution of void fabric. The new method with two scalar described the pore distribution on the plane, with the changed of pore geometry relationship, which degraded to the existing description format naturally. Image analysis validated the rationality of the new method.