Effect of Bed Characteristics on Sediment Motion

床面特性對泥沙運動的影響研究

周雙(SHUANG ZHOU) ； 張根廣(GENGUANG ZHANG)

《台灣水利》 68卷1期 (2020/03) Pp. 44-51

https://doi.org/10.6937/TWC.202003/PP_68(1).0005

摘要

The threshold of non-cohesive uniform sediment motion on a horizontal sedimentary bed, under a unidirectional steady uniform stream flow, has been analytically modeled using the following concepts: (1) The randomness of sediment movement is based on the randomness of the mean flow velocity and the particle position parameter, and the exposure angles follows the Gaussian distribution by analyzing the experimental data. (2) The correction coefficient of bed roughness has a definite physical meaning and it has a linearly proportional relationship with the coefficient of the bed area (the bed structure coefficient). The formula obtained using the present model has been compared with the formulas proposed by different investigators. The present results have an excellent agreement with the experimental data reported by other papers. The present model provides the accurate estimation of the threshold shields parameter and the threshold flow velocity for the initiation of bed particle motion.

關鍵字

Exposure degree ； Roughness ； Threshold velocity ； Sediment motion

並列摘要

為了進一步量化泥沙起動標準，本文提出以下概念：（1） 泥沙起動的隨機性由顆粒位置的隨機性和作用流速的隨機性共同決定，且暴露角服從高斯分佈；（2） 床面糙率修正係數與床面面積係數（床面結構係數）有關，且二者俱有線性關係。以上述概念為基礎，本文構建了一個泥沙起動數學模型，並與其他研究者公式進行了對比，結果表明，本文公式可以預測無粘性泥沙顆粒的起動流速和起動拖曳力，且與試驗數據符合較好。

並列關鍵字

暴露度 ； 粗糙度 ； 起動流速 ； 泥沙運動