| Summary: | 碩士 === 國立中興大學 === 水土保持學系 === 91 === The plain railing device has many steel I-beams mounted on the two consecutive check dams. Also there is an angle between the railing bar and the channel. The device can separate the coarse cobble and water when debris flow passes through it. In order to prevent the debris flow remixing, the channel is divided into main channel and by-pass. The coarse cobble can move above the I-beam screen and deposit in the main channel. The fine particle and water will drop through the I-beam screen and flow to the downstream in the by-pass.
By changing the height difference of two check dams and the railing bar length, there will be different condition of the railing slope. One purpose of this experiment is to analyze the relationship between the rate of separating coarse cobble and the railing slope in different railing bar length. Another purpose is to find out the reasonable soil halting factor to satisfy the expected rate of separating coarse cobble. At last we have to decide what kind of I-beam and what size of railing interval should be used in some cases at a job site. The result of this experiment are described as follows:
1.There is a repeated phenomenon of move and stop in three conditions of railing bar length, when the debris flow moves through the device with a gentle slope. The phenomenon is more obvious when the railing bar length is longer.
2.When the slope of the railing bar is between 30 and 40 degrees, the rate of separating coarse cobble is between 1 and 2. It is confirmed to the expected railing condition.
3.When the soil halting factor is between 5 and 10, the rate of separating coarse cobble is also confirmed to the expected railing condition.
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