Application of Soft-X ray to Analyze the Micro-Struture of Flow in Porous Media

饱和土壤中的液体流动由著名的达西定律描述。另一方面，通过使用非饱和导水率（KAPPA）计算非饱和水流，该导水率是吸力（PSI）或含水量（rheta）的函数。非饱和流的计算实际上利用了该函数。假设土壤是由各种粒径的球形颗粒组成的，可以从微观角度分析两个颗粒之间的持水体积，并获得PSI和rheta之间的理论关系。由于自然界中大多数砂粒倾向于具有高球形度，因此将其视为球形是合理的。一种是粒子上的非常薄的水膜，另一种是两个粒子之间的摆动水。如果我们将我们的考虑集中在直径大于10 μ mm的颗粒上<-3>，则在10 μ m的颗粒中的保水体积为100 μ m。 ...更多信息 孔隙中的水可以看作是颗粒上的自由水，而忽略膜上的水。在非饱和条件下，由于自由水的表面张力作用，自由水在两颗粒之间产生一个摆动环，本文提出了一个新的概念模型，从微观上分析了由不同粒径颗粒组成的非饱和材料中吸力与持水体积之间的关系。此外，所提出的模型已被用来估计PSI和rheta之间的关系，假设相同的规则包装。结果总结如下。(1)如果相邻颗粒彼此严格接触，则吸力随着保水体积的增加而急剧减小。(2)对于相同的持水体积，吸力随颗粒半径的增大而增大。(3)在含水率较低时，模型计算值与实验值吻合较好;但在含水率较高时，模型只考虑了两个颗粒间孤立的摆动环，无法进行计算，需要进一步研究多个颗粒间的摆动环.少

The flow of liquid in saturated soil is described by the well-known Darcy's Low. On the other hand, the unsaturated water flow is calculated by using unsaturated hydraulic conductivity (KAPPA), which is a function of the suction (PSI) or water content (rheta). This calculations of unsaturated flow make use of this function in practice. Assuming that the soil is composed of spherical particles with various grain sizes, it is possible to analyze the water retention volume between two particles from a microscopic standpoint and to obtain the theoretical relationship between PSI and rheta. Because most sand particles in nature are inclined to have high sphericity, it is reasonable to consider them as spherical.Generally, the water retained in soil is grouped into two categories. One is very thin film water on a particle, and the other one is pendular water between two particles. It we focus our consideration on the particles larger than 10^<-3> mm in diameter, the water retention volume in … More the pores can be regarded as free water on a particle, and to ignore the film water. Free water produces a pendular ring between two particles under unsaturated conditions because of the surface tension acting on the free water.In this study, a new conceptual model from a microscopic to analyze the relationship between suction and water retention volume in unsaturated material composed if particles with different sizes is proposed. Furthermore, the proposed model has been used to estimate the relationship between PSI and rheta for the assumed identical regular packing. The results are summarized as followings.(1) If adjacent particles contact strictly with each other, suction radically decreases with an increase of the water retention volume.(2) For the same water retention volume, suction increase with the increment of radius of the particle.(3) Calculated values from the proposed model agree well with the experimental results for the lower water content ; however, for the higher water content, the calculation cannot be carried out because proposed model focuses on only isolated pendular rings between two particles.Further work is needed to analyze pendular rings among multi-particles. Less