堰壩投潭沖刷坑特性因子之研究

THE CHARACTERISTIC FACTORS OF SCOUR HOLES BY FREE OVERFALL FLOW

陳正炎(Jen-Yan Chen) ； 郭信成(Hsin-Cheng Kuo) ； 鐘文傳(Wen-Chwan Jong)

《中華水土保持學報》 24卷2期 (1993/11) Pp. 81-89

https://doi.org/10.29417/JCSWC.199311_24(2).0008

摘要

要保護工係堰壩下游渠床不可或缺的安全設施，其設計主要依據爲沖刷坑之形狀和大小，故了解受制投潭水作用下沖刷坑之特性因子若何，實爲最基本的研究。本文旨在利用理論推導解析，並配合水工試驗驗證，以釐出當達動態平衡時不同渠床質佈置，其穩定沖刷坑特性因子間之關係。研究結果發現不論渠床質爲均一粒徑或級配粒徑佈置者，形狀因子C_b、C_s，與C_i，之特性係數C_(sb)=C_s-C_b≥1及C_(is)=C_i≥C_s1沖刷坑長度L_i-L_b爲最大刷深y_s，之2.5〜5.0倍，以及體積因子A_s≥Ⅱ/ 2之定量關係。

關鍵字

投潭水 ； 沖刷剖面 ； 形狀因子 ； 體積因子

並列摘要

Protection works are needed at the downstream of hydraulic structures for safety consideration. They are designed primarily based on the shapes and sizes of scour holes. Therefore, it is the fundamental and important research to find the relationships among the characteristic factors of scour holes. In this study, the scouring phenomena of free overfall flow are conducted with sandy soils as the channel bed of the weir's downstreams. Two types of sandy soils are used. They are of uniform size and graded distribution. The experimental observations will be compared with the theoretical results. It is indicated that all the shape factors, C_b, C_s and C_i are functional with the drop number N_d and the relative diameter G. Meanwhile, it's verified the characteristic coefficients of the shape factors, C_(sb)(=C_s-C_b) and C_(is)(=C_i-C_s) are both greater than one, and the volume factor of the stable scour bole, A. is greater than II/2. The results also show that the ratio of the length of the stable scour hole, L_i - L_b to the maximum scour depth, y_s is in the range of 2.5 to 5.0.

並列關鍵字

Free Overfall Flow ； Scour Profiles ； Shape Factor ； Volume Factor