分洪工程水工模型試驗

本研究主要針對磺港溪分洪工程系統進行水工模型試驗。水工模型分為三座，模型A目的在於瞭解分洪工程完工後之分流流量及分洪效益其中包括以六種流量下探討分洪工程之靜水池分洪流量、靜水池水理現象，模型B及C亦於六種流量下瞭解各局部束縮漸變能量損失及其排洪效益。試驗結果顯示當靜水池寬頂堰堰前之水深與水位之比值((Y2-W2)/Y2)大於0.17時，寬頂堰溢流口將不依據臨界流流況排放及若改善局部漸變束縮段，磺港溪流量於Q=120.00cms下可增加壓力箱涵分流量Q=11.58cms，另外下游基隆河水位為定值時，磺港溪流量愈大，壓力箱涵流量亦愈大，但下游基隆河水位愈高，上游磺港溪入流量為定值時，壓力箱涵分流量則受迴水影響愈大導致分流量愈小。

關鍵字

分洪工程；寬頂堰；溢流堰；能量損失係數；水工模型試驗

並列摘要

This study focuses on hydraulic model test on the flood diversion project of Hung-Kang Creek. There are three hydraulic engineering models. The objective of Model A is to understand, at the diversion project’s completion, the diverted flow rate and flood diversion efficiency, including an analysis of the stilling basin’s diverted flow rate and hydrological phenomena under six flow rates. Models B and C also analyze energy loss at each of the local constriction transitions as well as its flood diversion benefit. The modeling test result shows that (1) if the ratio of water depth to water level at the stilling basin upstream of the broad-crested weir is greater than 0.17, the overflow outlet of the broad-crested weir will not be under critical flow conditions; and (2) when the Hung-Kang Creek’s flow rate is at 120.00 cms, the pressure box culvert’s diversion rate may be increased to 11.58 cms by slightly improving local constriction transition sections. Furthermore, it is determined that the flow rate of pressure box culvert increases with Hung-Kang Creek’s flow rate provided the downstream Keelung River’s water level remains constant. However, if the upstream inflow rate of Hung-Kang Creek remains constant, the higher the water level at Keelung River, the further pressure box culvert’s diversion rate is reduced by backwater effect.