應用抽泥浚渫提升防淤隧道排砂效率之試驗研究

臺灣境內位於板塊交錯區域，地表起伏大，河川坡陡流急，水資源難以儲蓄利用。面對如此問題，為了防洪減災、有效治水，最直接有效之方法就是興築水庫。然而，水庫建設後必須處理泥砂淤積等問題，才能延長其使用年限。為求延長水庫壽命以及永續經營，經濟部水利署南區水資源局推動之「曾文水庫防淤隧道工程」計畫成為全球首座使用象鼻鋼管工法興建之排砂防淤隧道，大幅降低清淤經費。對於水庫之異重流運移機制、水力排砂、設施操作及閘門啟動時機決策上，目前已有許多研究探討。因此，本研究基於既有之曾文水庫資料與研究，以其新建象鼻防淤隧道為主要研究項目，探討浚渫排砂之抽泥泵系統(Hydraulic Dredging Systems)搭配防淤隧道之防洪防淤操作，提升防淤隧道之排砂成效。曾文水庫目前主要防淤措施雖然以庫區浚渫抽泥為主，然受限於下游河道暫置空間有限，因此若能輔以開啟防淤隧道時機，將抽泥渾水投放至防淤隧道入口有效流場範圍內，則可增加防淤隧道之排砂效率，因此本研究以曾文水庫象鼻管防淤隧道為主要研究對象，針對抽泥浚渫置放淤防淤隧道入口區域之情境，透過水槽試驗之方式，評估此一操作情境下之防淤隧道排砂效率。試驗上分析流量、濃度、抽泥管出口位置等因素，進一步分析抽泥管出口泥砂量與防淤隧道排砂量之相關性。經研究結果歸納分析，得出防淤隧道排砂效率與抽泥管出口距離比尺、出入流量比尺、抽泥管出流雷諾數比尺及射流比尺之關係式，可供實務上浚渫抽泥結合象鼻防淤隧道操作之參考，並期盼未來對曾文水庫防淤工法上能有所貢獻。

關鍵字

水庫防淤；浚渫；象鼻防淤隧道；排砂效率

並列摘要

Taiwan locates on the boundaries of two plates, resulting in the characteristics of salient relief and short rivers with steep slopes. Therefore, the water resources can hardly be stored. The most efficient solutions to this issue are building reservoirs and dams in order to reduce disasters and provide adequate flood protection. However, for the purpose of extending the duration of a reservoir, the hydraulic structure needs to be monitored and upkept properly. In the case of Zengwen Reservoir, a project of constructing a sediment-sluice tunnel implemented by Southern Region Water Resources Office, WRA, MOEA has become the very first construction in the world to apply the elephant-nose desilting tunnel to reservoir desiltation. And it has also been proved that it reaches a certain level of success. Since several studies of density flow, sediment-removal systems, facilities operation, and the timing of venting turbidity currents have been carried out, A physical model study was conducted to investigate the possible scenarios of combining Hydraulic Dredging Systems with the elephant-nose desilting tunnel of Zengwen Reservoir for sediment desiltation and further research discussing venting efficiency. Various parameters that affected the efficiency were studied, including discharge, concentration, and distance between the desilting tunnel and slurry pipe. Moreover, several characteristic arithmetic expressions were acquired, providing a reference for the implementation of the above scenarios. Hopefully the study makes a contribution to desiltation management of Zengwen Reservoir.

並列關鍵字

Reservoir desiltation ； Dredging system ； Elephant-trunk desilting tunnel ； Desilting efficiency

參考文獻

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應用抽泥浚渫提升防淤隧道排砂效率之試驗研究

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