摘要:
黄土的工程性质与黄土的微结构特性密切相关。为了研究马兰黄土的二维孔隙特征和三维结构表征,实验土样用显微CT进行扫描,并重建三维图像。首先利用高斯滤波对切片图像进行降噪处理,接着用二值法对灰度图像进行统计得到二维孔隙特征,在此基础上重建三维图像,分别提取切块、团聚体和土颗粒的三维图像,得到它们的三维结构表征。研究结果如下：（1）对二维孔隙面积进行计数分析,土样的孔隙面积集中在0~2 000 μm2范围内；通过比较孔隙面积与总数的关系,可知中孔隙对土体的性质影响最大；对不同层面的孔隙比对比后,发现土体的孔隙分布在宏观上可视为均一的,微观上在土体的不同部位分布是不同的。（2）通过对三维图像进行分析,得到团聚体中土颗粒间有4种组合关系,分别为接触、连接、穿插和融合关系；土颗粒形态可分为4类,分别是椭球形、锥形、片形和条形。
Abstract:
The physical and engineering properties of loess have close relationships with the characteristics of its micro-structures. The micro-CT experiments were performed for reconstruction of 3D images to illuminate the 2D pore characteristics and 3D structure characterization of the Malan loess. Firstly, slice images were corrected through the Gaussian filtering and gray images were obtained with the binary method for 2D pore characteristics. Moreover, 3D images were reconstructed in accordance with the analysis of the 3D structure characterization, which was summarized by the 3D chop, aggregate and particle.The research results show that (1) as the results of 2D pore area counting analysis, the pore areas of the soil sample tend to concentrate in the range of 0~2 000 μm2. Comparing the total number with the area of pore, it can be concluded that the medium-sized pores play an important role in the soil properties formation. It is also found that the soil pore distribution on the macro level can be regarded as uniform after comparing different layer numbers of void ratio. However, its distribution in different parts of the soil is different from a micro level.(2) Depending on the analysis of the 3D images, it is found that there are four combination relationships among the soil particles in the internal of aggregate: contact, connection, penetration and fusion, and the soil particle morphology can be classified into four shapes: spheroidicity, cone, sheet and bar.
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