In the hydrologic cycle, sandy soils play the role of a connecting reservoir of surface water and groundwater, particularly in arid areas. Therefore, to provide water conservation and ecological environment protection, it is important to study the soil water behavior in the unsaturated zone. At present, the CT-scan method is commonly used to study the soil hydraulic properties. In the field of materials science, the industrial CT high-resolution instruments are applied for quantitative research on the porous microstructure and fluid filtration law in sandy soils.

In this study, we have studied five samples of sand scans of the quartz sand and CUGB coarse sand types. The industrial-type CT instrument XTH225ST was used for the sample microstructure scanning. In order to identify water: air, and solid particle distribution of the sample cross section, and to analyze the particle size distribution and moisture content, the scanned images were processed using the VG-Studio and ImageJ software.

Comparing the CT-scan results of the four quartz sand samples, it can be concluded that the optimal particle size, ranges from 1 to 2 mm. According to the porosity quantitative analysis, with decrease in the particle size, the total porosity grate soil sample increases. After applying the image recognition and VG- Studio software, we can see that for different particle sizes of the sand sample, the average pore size increases with increase in the particle size.

To study the moisture absorption and desorption phenomenon, two samples of the CUGB coarse sand are experimentally studied. The particle size of the samples range: from 1 to 2 mm. The CT scanning analysis is used to obtain the unsaturated characteristic curve of the soil when the moisture content reaches stability. Due to the lag phenomenon, the characteristic curve of the soil moisture has an obvious “loop,” or hysteresis, shape. As shown by a 3D modeling, the distribution of capillary water in the sand column is complex, and the water flow forms multiple winding paths, like “worms” creeping in the soil.

The CT-scan method is used to overcome the limitations of the traditional experimental methods and to evaluate the relationship between the moisture content and the matrix suction. The obtained characteristic curve of soil moisture can be used to improve the efficiency of technological operations. The CT-scan method provides a new way of evaluating the water distribution characteristics of unsaturated soil.

在水文循环中，沙土起着地表水和地下水的连接水库的作用，特别是在干旱地区。因此，为提供节水和生态环境保护，研究非饱和区土壤水分行为具有重要意义。目前，CT扫描法通常用于研究土壤的水力特性。在材料科学领域，工业CT高分辨率仪器被用于对砂质土壤中的多孔微结构和流体过滤规律进行定量研究。

在这项研究中，我们研究了石英砂和CUGB粗砂类型的五个砂扫描样本。使用工业型CT仪器XTH225ST进行样品微结构扫描。为了识别样品横截面上的水：空气和固体颗粒分布，并分析颗粒尺寸分布和水分含量，使用VG-Studio和ImageJ软件处理了扫描的图像。

比较这四个石英砂样品的CT扫描结果，可以得出结论，最佳粒径为1到2 mm。根据孔隙度定量分析，随着颗粒尺寸的减小，总的孔隙度炉排土壤样品增加。应用图像识别和VG-Studio软件后，我们可以看到，对于不同粒径的砂样品，平均孔径随粒径的增加而增加。

为了研究水分的吸收和解吸现象，对CUGB粗砂的两个样品进行了实验研究。样品的粒径范围为1至2毫米。当含水量达到稳定时，使用CT扫描分析获得土壤的非饱和特性曲线。由于滞后现象，土壤水分的特征曲线具有明显的“回圈”或滞后形状。如3D模型所示，毛细水在沙柱中的分布很复杂，水流形成了多个缠绕路径，就像在土壤中蠕动的“蠕虫”一样。

CT扫描法用于克服传统实验方法的局限性，并评估水分含量与基质吸力之间的关系。所获得的土壤水分特征曲线可用于提高技术操作效率。CT扫描法为评价非饱和土的水分分布特征提供了一种新途径。