| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2003: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2002: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
The erosion process of soft cohesive sediments, which were deposited naturally on a river bed, is investigated in this study. Extensive series of experiments, conditions of which were set systematically, were conducted to evaluate the erosion rates by running water in a closed conduit. Test samples consisted of a mixture of silica sand, clay and water, the composition of which was set to be a variable. The main factors which govern this process were found be the clay content ratio (the weight ratio of clay to the total sediment), the water content ratio (the weight ratio of water to the clay), and a frictional velocity of flow, a water temperature, the size of silica sand and the dry-wet history. The effects of these parameters on the erosion rate were evaluated quantitatively. The erosion rate formula was also derived on the basis of experimental results. Also, the mechanism of this process was examined and made clear to a certain extent. In addition to these fundamental studies, the portable measuring system of erosion rate in a real river was developed, and a series of measurement was also conducted confirm the validity of this erosion test.
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