台灣西部沿海的海下工程，經常需要傾倒砂石來保護海底管線，但相關知識與經驗不足，覆蓋的準確度往往不如預期，因此本研究發展一套砂石沉降預測模型來提昇準確度，以降低開支。本文以多固體圓球顆粒仿砂石粗糙表面在橫向流中的沉降落點與行為來進行研究，透過實驗驗證我們簡易的力學模型可以在一定範圍中預測正確的落點範圍。
　　流場的實驗條件假設為四個不同速度的橫向流0.1 ~0.76 m/s，使用粒徑平均為1.306 cm的玻璃圓球模型，最大雷諾數約為10,000。計算過程中，我們考慮了重力、浮力、阻力、附加質量力、側向力等因素，並加入流速不均與玻璃圓球模型直徑不均的影響，觀察到玻璃圓球模型落下時的旋轉行為會造成側向力，影響玻璃圓球模型落點位置。預測模型的落點範圍，與實驗比較，預測模型能符合大部分的實驗結果。

Dumping sand and gravel is a way used to protect pipelines under west coast of Taiwan. However, the coverage and accuracy was not as good as expected. The research is aimed to increase the accuracy and reduce the cost by creating a prediction model of sand settling.
This research analyzed experimental data of particle settlement positions in a cross flow. The trajectories and settled positions are predictable by a simple mechanical model.
The cross flow velocity is in the range of 0.1 ~ 0.76 m/s. The experiment used glass spheres of 1.306 cm diameter with maximum Reynolds number up to 10,000. Gravity, buoyancy, drag, added mass, and lift are considered in the prediction model as well as the effect of flow velocity variation, and variation of the diameter of the glass sphere. It's important to consider the effect of the lift acting on spheres caused by the rotation behavior. The result of prediction model matches most of the settlement experiments results with 95% confidence level.

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【書籍資料】
[11] Yong Bai and Qiang Bai,“Subsea pipelines and risers”, Elsevier, 2005.
【網站資料】
[12]國科會海洋學門海洋資料庫
(http://www.ncor.ntu.edu.tw/ODBS)，下載日期：2010/03/21。
[13]圖1.1.1攝於歐洲北海海底的裸露管線
(http://sine.ni.com/cs/app/doc/p/id/cs-11239)，下載日期：2010/03/21。