Morphological transitions for pore water and pore air during drying and wetting processes in partially saturated sand
Morphological transitions for pore water and pore air during drying and wetting processes in partially saturated sand
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DOI：
10.1007/s11440-020-00939-3
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发表时间：
2020-02
期刊：
影响因子：
5.7
通讯作者：
Ryunosuke Kido;Y. Higo;Fukushi Takamura;Ryoichi Morishita;Ghonwa Khaddour;S. Salager
中科院分区：
文献类型：
--
作者：
Ryunosuke Kido;Y. Higo;Fukushi Takamura;Ryoichi Morishita;Ghonwa Khaddour;S. Salager
持水特性对于模拟部分饱和砂土的力学和水力特性具有重要意义。土壤水分特征曲线在干湿过程中具有滞后性。为了更好地了解部分饱和土壤的持水特性，孔隙水相和孔隙气相的形态转变，如体积分布，空间分布和连续性在干燥和湿润过程中的微观研究是至关重要的。在本研究中，不同的水保持状态的部分饱和砂的持水试验期间，使用微焦点X射线计算机断层扫描（CT）可视化。将试验得到的CT图像分割为土颗粒相、孔隙水相和孔隙气相。然后，一系列的图像处理，腐蚀，膨胀和集群标记应用到图像中，在这个顺序来量化的集群体积分布，集群的数量和连续性的孔隙水相和孔隙空气相。使用图像处理的结果揭示了孔隙空气相和孔隙水相在饱和度降低和增加的情况下的形态转变，然后基于这两个相的形态表征了保水状态。讨论了形貌对滞后的影响。
Water retention characteristics are important for modeling the mechanical and hydraulic behavior of partially saturated sand. It is well known that the soil water characteristic curve shows hysteresis during drying and wetting processes. For a better understanding of the water retention characteristics of partially saturated soil, a microscopic investigation of the morphological transitions for the pore water phase and the pore air phase, such as volume distribution, spatial distribution and continuity during drying and wetting processes, is crucial. In the present study, different water retention states of a partially saturated sand were visualized during water retention tests using microfocus X-ray computed tomography (CT). The CT images obtained from the tests were segmented into the soil particle phase, the pore water phase and the pore air phase. Then, a series of image processing, erosion, dilation and cluster labeling was applied to the images in this order to quantify the cluster volume distributions, the number of clusters and the continuity of both the pore water phase and the pore air phase. The morphological transitions for the pore air phase and the pore water phase, subjected to decreasing and increasing degrees of saturation, were revealed using the results of the image processing, and then, the water retention states were characterized based on the morphologies for the two phases. The influence of the morphologies on the hysteresis was discussed.