| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2002: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
The purpose of the research is to clarify the applicability of the remediation technology of the contaminated soils by freezing and thawing. In this research, the followings topics were examined: Movement of the water-soluble pollutant by the freezing condition, types of the soil, etc.
In the 2002 fiscal year, cooling rate, temperature gradient, effect of the load, and the water supply conditions were examined for cohesive frost susceptible soils.
From the experimental result, it was observed in all test conditions that the solute was moved to the cold side from the high temperature side in all conditions. From this fact, the direction of the moisture and solute transport in the freezing frost susceptible soils seem to be generally to the cold side from the high temperature side.
In the 2003 fiscal year, the washing technique which based on increase of the hydraulic conductivity of cohesive soil after thawing was examined. Especially, the experiment focus is on the influence of the type of soils and loads in the change of the hydraulic conductivity.
The main results are as follows. First, in the series of the experiments, the increase of hydraulic conductivity after freezing and thawing was observed in the range to 100kPa. Next, there is a large difference in the change of the hydraulic conductivity in the types of soils. The hydraulic conductivity increased to several hundred times in Kanto loam, and to about 10 times in Fujinomori clay. Especially, in case of the Kanto loam, the hydraulic conductivity increased to 10^<-3>cm/s to 10^<-4>cm/s that is the value of sandy soil, though hydraulic conductivity in the unfrozen condition is in the range between 10^<-6>cm/s to 110^<-7>cm/s that is the value of cohesive soil. In addition, the hydraulic conductivity differed even in equal void ratio in before and after of freezing and thawing.
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