Studies on the Subsoil Improvement of Sea Bottom Polder based on the Analysis of Salt and Ion Behavior in Clayay Soil

本文介绍了对笠冈圩田进行石膏粉土改良的现场研究和室内试验。研究结果如下：1.现场研究表明，由于石膏提供的钙离子与吸附的钠离子发生交换反应，扩散双电层减少，自由水增加。控制了石膏混合层中的分散反应，使土壤处于絮凝状态。同时，土壤物理性状也得到了改善.结果表明，土的沉降量是石膏改良钠质粘土效果的最佳判断标准. 1985 ~ 1986年跟踪调查了钙离子吸附钠的进展情况。1984年底，将石膏撒至50 cm深，并根据考虑空间变异的阳离子交换反应合理方程计算石膏量。因此，交换进展顺利，底土改良效果显著。此外，盐浓度的长期下降已经变得明显。

The Fieid studies and laboratory experiments about a process of subsoil improvement after gypsum dressing into Kasaoka polder had been carried out. The results are as follows;1. The field study showed the decrease of diffusion double layer and increase of free water because of the exchange reaction of adsorbed sodium ion by calcium ion supplied from gypsum. Consequently, the dispersion reaction in gypsum mixed layer had controled and soil changed to floculation state. At the same time, the improvement of soil physical characteristics had gained.2. It was showed that the sedimentation volumes of soils was most adequate judgment standard for the improvement progress of sodium clay with gypsum.3. The progressive situation of adsorbed sodium to calcium ion had been pursued and investigated from 1985 to 1986. The gypsum was scatterd and mixed until 50cm depth in the end of 1984 and its quantity was calculated from rational equation of cation exchange reaction considering spatial variance. Accordingly, the exchange had progressed smoothly and the subsoil improvement was remarkable. Furthermore, the long-term decline of salt concentration had become clear.