拋石保護控制固床工趾部局部淘刷之研究

Riprap Protection in Controlling Local Scour at the Toe of a Groundsill

吳嘉俊(Chia-Chun Wu) ； 黃炳錡(Ping-Chi Huang) ； 吳雅筠(Ya-Yun Wu)

《中華水土保持學報》 47卷3期 (2016/09) Pp. 147-155

https://doi.org/10.29417/JCSWC.201609_47(3).0004

摘要

本研究利用1:50縮尺之系列固床工模型進行水工實驗，以探討拋石保護段長度及拋石粒徑大小對減輕固床工趾部渠床淘刷的效益。除了瞭解拋石保護措施下渠床局部淘刷的縮減與淘刷機制外，更透過因次分析，尋求拋石保護段長度與拋石粒徑之無因次設計公式。研究結果顯示，拋石雖可以減輕固床工趾部渠床的局部淘刷，但並不能完全消除。當拋石保護段的長度為固床工間距的1/4時，渠床淘刷深度的最大縮減百分比隨著拋石粒徑與渠床床砂粒徑比的增加而從83%降低為76%；當拋石保護段的長度為固床工間距的1/2時，淘刷深度的最大縮減百分比則大致持平。至於淘刷坑長度的最大縮減百分比，則隨著拋石粒徑與渠床床砂粒徑比的增加由64%提高為84%。

關鍵字

拋石保護 ； 局部淘刷 ； 拋石長度 ； 拋石粒徑 ； 固床工

並列摘要

An array of 1:50 scaled groundsill models was installed in a semi-circulating flume to study scour mechanics and effectiveness of riprap protection lengths and riprap sizes. Results of this study show that riprap protection at the toe of a groundsill is unable to completely eliminate the local scour, but it is capable of reducing scour depth and scour length. A dimensionless relationship was also derived in this study to help select riprap protection lengths and riprap sizes. The maximum percent of scour depth reduction can be reduced from 83% to 76% with respect to the increase of riprap size to channel sediment size ratio when riprap protection covers 1/4 of the groundsill interval. Percent of reduction remains fairly constant when riprap protection covers 1/2 of the groundsill interval. On the other hand, the maximum percent of scour length reduction increases from 64% to 84% with respect to the increase of riprap size to channel sediment size ratio.

並列關鍵字

Riprap protection ； local scour ； riprap length ； riprap size ； groundsills