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Analysis of the relation between change of soil water phase and salt concentration by the measurement of dielectric constant in high frequency

高频介电常数测量分析土壤水相变化与盐浓度的关系

基本信息

批准号：
08660295
负责人：
MITSUNO Toru
金额：
$ 1.47万
依托单位：
KYOTO UNIVERSITY (1998)Okayama University (1996-1997)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

Some interesting phenomena occur on the interface between different materials. In this study, the phenomena at the freezing front, that is a interface between frozen and unfrozen soil, are investigated for a saline soil on the view point of an electromagnetic phenomena.By the laboratory experiment for soil column, it is certified that much sensible heat occurs at the freezing front, is transferred through the frozen soil layer to the surface, and is released to the atmosphere. At the same time, it becomes clear that the soil water in liquid phase moves to the freezing front, and the soluble salt moves accompanied with the soil water to be accumulated there. By the measurement of dielectric constant of soil, it is recognized that much unfrozen water exists below 00C under the high salt concentration.The new technique to measure the depth of the interface between different soils is developed based on that the electromagnetic signal conducting in metal rod buried into soil reflects at the interface. The freezing front, that is, the interface between frozen and unfrozen soil, is precisely measured by this technique.The soil freezing phenomena are very complicated because heat, water and other materials are moved simultaneously by the soil frost. Some dynamic phenomena are, therefore, observed near the freezing front. The movement of the freezing front is investigated, and then the equation of the proceeding and receding of the front is derived and certified to predict well the movement of the front by the numerical simulation.

在不同材料的界面上会发生一些有趣的现象。本文从电磁现象的角度研究了盐渍土冻结界面处的现象，通过室内土柱实验，证实了大量的显热发生在冻结界面处，通过冻土层传递到地表，并释放到大气中。同时，土壤液相水向冻结前沿运移，可溶性盐随土壤水运移并在冻结前沿积累。通过对土壤介电常数的测量，认识到在高含盐量条件下，00 ℃以下土壤中存在大量未冻水，并利用埋在土壤中的金属棒传导的电磁信号在界面处反射的原理，提出了一种测量不同土壤界面深度的新技术。该技术可精确测量冻结前沿，即冻结与未冻结土壤的界面，土壤冻结现象是非常复杂的，因为土壤冻结同时引起热、水和其他物质的运动。因此，在冻结锋附近观察到一些动力学现象。研究了冻结锋的运动规律，推导了冻结锋前进和后退的方程，并通过数值模拟验证了该方程能较好地预测冻结锋的运动。