| Summary: | 碩士 === 國立中興大學 === 水土保持學系 === 88 === ABSTRACT
In the past, researches of the silt-type dam apparently focused on the trop efficiency of the debris flow and the ratio grain concentration by volume, which are influenced by factors such as the silt density of the silt-type dam, and the relative opening width (b/d max). As to the studies of the scouring hole, they also concentrated in the traditional check dam and the flood detention dam. Researchers seldom pay attention to the downstream scouring hole of the silt-type dam. Under such circumstances, we use indoor flume experiment to discuss the types of the downstream scouring hole resulting from three different discharges, three different slopes of channel, and seven kinds of silt density in this study.
As a result of the experiment, with the increase of the discharge and the slope of channel, the factors of the scouring hole consequently increase. However, with the same slope and the same discharge, the factors of the scouring hole don’t increase although the silt density decreases. The interrelationship between them shows irregular changes.
Besides, the heavier the silt density of the silt-type dam, the more independent between each down-stream scouring hole, and the maximum of the factors of the scouring hole occurs mainly in the center of the channel. But as the silt density becomes smaller, the situations reverse. The scouring hole forms a uniformly narrow long strip type, and the location, which the maximum of the factors occurs, is not certain.
Keywords：the silt density、relative opening width、the ratio grain concentration by volume
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