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Experiment on the Hydraulic Characteristics of Slit-Type Check Dam
slit-type check dam
coefficient of transformed section
二種試 料（粗：2mm、 細：0.84mm），於21cm寬之渠槽進行水理試驗，
Abstract The purpose of this study is to investigate the relationship between the width of opening and the hydraulic parameters for slit-type check dam.Three channel slopes (3°、6°、9°),three flow rate and two size of sediments(gravel：2mm、sand：0.84mm) were used to conduct the channel experiments in the channel with 21cm width.To realize the effect of the interception of the slit-type check dam,the multiple opening slit dam was transformed to single opening slit dam in this study.The result are obtained as follow： 1. The variation of Froude number is not distinguished when the flow through the traditional check dam.This is expressed that the constrictive effect of the check dam is not distinguished. 2. Because the flow can''t scoure out the sediments at the upstream of the traditional check dam under the condition of the water supplied,the dam will almost intercept sediments.But the height of opening in slit dam is lower than the traditional dam,so the sediments will transport through the opening to the downstream with the flow and there is a pit to scoured out at the upstreamof dam. 3. The scoured pit where is formed between the dam and the original deposited sediments has a cushioning effect for the flow,the velocity will be decreasedat the scoured pit.When the flow through the opening of slit dam,the velocity was increased with the contrictive effect. Then,the water depth at the opening of dam is lower than that at the upstream. 4. Under the condition of this experiment,if channel slope or discharge is large enough to maybe the flow water over the top of dam,the velocity at the opening of dam was slower than that before the pit being formed. 5. It is derived that the velocity at the opening of dam is a negative relation with the coefficient of transformed section, and it is proved to be correct by the experiments.A larger of the coefficient of transformed section means that the slit dam has a higher effect for stabilized the deposited sediments.And the more the opening numbers is,the higher opening opening effect is.It is meanning that the constrictive effect is not significant with a more number of opening,and the energy loss also is not significant.Therefore,the scoured pit at the upstream is smaller than that with the less opening numbers.
|Appears in Collections:||水土保持學系|
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