固床工間距之探討（I）

Study on the Interval of Groundsill Works (I)

游繁結(Fan-Chieh Yu) ； 張則安(Tzer-Anne Chang)

《中華水土保持學報》 25卷3期 (1994/09) Pp. 171-179

https://doi.org/10.29417/JCSWC.199409_25(3).0006

摘要

固床工係橫置溪床爲保護溪床及溪岸避免淘刷之構造物，通常在設計固床工間距時，多以經驗方式推估，本文則擬從現地調査及靜態平衡坡度理論探討固床工間距之決定方法。經調査結果顯示，在20條設置固床工之野溪中，3條野溪溪床有淘刷之不安定現象，4條野溪現場植生密布，另外13條野溪溪床則呈現安定之狀態。但就整體而言，固床工對上游構造物及溪岸之保護效果尙稱良好。將其水理資料配合溪床之表面粒徑加以分析後，發現溪床之砂粒福祿數與現場實測坡度有成正比之關係，且在溪床有顯著粗礫化現象及植生密布之情況下，溪床多呈安定之狀態。另依靜態平衡理論推估固床工間距時，溪床代表粒徑以d_(50)爲一適宜之參數，由該代表粒徑所推估之固床工間距與實測間距相當接近。

關鍵字

固床工 ； 靜態平衡坡度理論 ； 粗粒化

並列摘要

Groundsill is a structure which is laid across the stream and is inserted into the streambed to prevent .the scouring. Besides, it also protects the stream banks to avoid scouring. Designing the interval of groundsills usually uses the empirical method. But in this study, we use a theory of stable equilibrium with data from field investigation to find an appropriate way in determining the interval of groundsills. The results indicate that, most of 20 torrents investigated are in the state of stable equilibrium, except 3 torrents in scouring. Among these stable torrents, there are 4 torrents which are well covered with vegetation. In general, all the groundsills are still standing firm to protect the upstream structures and stream banks. For stability analysis, the Froude number of sand particle has a positive relation to the slopeness in the stable torrents. Meanwhile, these stable torrents are with armour coat, and vegetation cover on the streambed. Using the theory of stable equilibrium, d_(50) is a suitable parameter for calculating the interval of groundsills. The calculated values agree well with the field measurements.

並列關鍵字

Groundsill Work ； Theory of Stable Equilibrium ； Armor Coat