Overflowing Hydrodynamic Characteristics Of Vegetation "Flexible Dam" And Sand-binding Mechanism

In order to solve river sediment disaster in our country, particularly resolve sand prevention, training for sediment and soil erosion problems in Xinjiang, this paper systematically concludes study the present condition of flow with plant. According to variations of two-dimensional flow after planted flexible dam, four districts along longitude are divided:inlet district, backwater district, plant dam district and recovery district, so as to more directly understand main reason of sediment retention of plant flexible dam. Flow boundary factors such as bottom slope, roughness and plant factors such as length and density of dam are analyzed to find how these factors effluence on the effect of sediment retention of plant dam. Then better type of plant dam is selected based on comparison of different type of dam.According to the clear water experiment data, studies flow characteristics of vegetation "flexible dam". Vegetation dam will interfere original flow pattern and make water depth of dam’s upper reaches rise, flow velocity let down, bed roughness rise and bed shear stress let down. These show that vegetation dam can reduce starting drag force and starting frequency of sediment in upper reaches. And can make athletic sediment deposit. Then according to the suspension current experiment data, by analyzing motion change of single particle before and after planting, sediment’s feature in the front of dam and trapping efficiency, proves that vegetation dam can intercept sediment, especially gentle slopes are better. Lastly, studies transportation characteristic of bed load sediment of upstream end before vegetation dam. Preliminarily clear sand-binding mechanism of vegetation "flexible dam".And by the indoor physical model experiment’s early result, proceeded number research to overflowing hydrodynamic characteristics of vegetation "flexible dam", established plant hydrodynamics equation, and proceeded the number calculation by fluent. It analyze the calculation result and proceeded the comparison to the experiment with model in the text, verified the dependable of the mathematics model and number calculation method for choosing. It’s very important meaning to apply vegetation "flexible dam" in the actual engineering. Lastly, studies transportation characteristic of bed load sediment of upstream end before vegetation dam, and base on the experiment, utilizing one-dimensional flow sediment mathematical model, and simulates bed silt calculating before vegetation dam. It shows that calculating result is similar to observation result, and has the certainly practical value.