本研究主要以實驗方式進行黏性泥沙在靜止水體與振盪流中之沉降行為研究，觀測黏性泥砂在沉降過程中隨著時間運動之濃度變化，並對沉降速度進行量測，以及比較靜態與動態沉降試驗之差異，並且探討不同條件下所產生之沉降行為差異，歸納其可能影響沉降行為之參數。
　　本研究運用於造波水槽內加裝隔板之方式，製造一類似U型管之空間，並且輔以造波系統在其一端推擠水體，達到所需之振盪流環境，並透過條件測試作業得振盪流條件之穩定範圍，總計進行五十七組沉降試驗，包含靜態條件與十八組振盪流條件與三種初始濃度條件之組合。試驗期間利用光學濁度計OBS於垂直深度上的排列來監測沉降過程的整體濃度衰減，運用沉降速度與懸浮泥沙濃度的相關性進行沉降速度之量化，並且使用超音波都卜勒流速儀ADV檢視區段內速度與擾動情形，引用雷諾擴散通量來量化其紊流擾動值。
　　藉由檢視不同條件間的濃度時序列、沉降速度時序列以及沉降速度與濃度之關係，本研究歸納出沉降行為與懸浮泥沙濃度相關外，亦受振盪流流速以及初始濃度兩參數之影響：振盪流流速參數將使濃度衰減趨勢變緩以及造成沉降速度下降，其最大沉降速度隨雷諾擴散通量增加而衰減之趨勢代表沉降行為受振盪流速度與懸浮泥沙濃度的紊流擴散所影響；初始濃度參數於靜態條件與低流速條件影響尚不顯著，當流速條件提高，沉降速度將隨初始濃度條件增加呈現衰減之趨勢。

　　　This study investigated the settling process of cohesive sediment under static water and oscillation flow. Suspended sediment concentration and settling velocity were measured in the experiment. It is attempted to investigate the parameters which influence settling behavior under different experimental conditions.
　　　The experiments were conducted in a wave-tank at Tainan Hydraulics Laboratory. Experimental setup was constructed by a U-tube-like space installing custom-made plates in wave-tank. Wave-maker was used to push water in wave flume and then generated oscillation flow. There are fifty-seven combinations of settling experiments which consisted of three initial concentration conditions and eighteen oscillation flow conditions, plus a static condition in this study. An array of OBS and an ADV were applied to measure the changes of concentration and velocity during settling process.
　　　From the experiments, the results concluded that settling behavior was not only influenced by concentration, but also by both velocity and initial concentration. The velocity of oscillation flow would slow down the settling behavior resulting in decreased settling velocity. The maximum settling velocity decreases with Reynolds number also indicated the influence of velocity of oscillation flow. On the other hand, the influence of initial concentration was unobvious at static condition and low velocity condition. Nevertheless, the settling behavior revealed a significant difference under high velocity condition. Settling velocity decreased as initial concentration increasing.

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