斷面水槽不規則造波試驗之適切性研究

本研究延續Chen (2004)、Twu (2005)、Lee (2011)及Tsai (2012)等之研究，分別以水工模型試驗結果及數值模擬方式，探討使用斷面水槽進行不規則波試驗，其造波波列選用之適切性。研究中利用合田良實的修正JONSWAP理論頻譜，代入指定的波高與週期進行等頻率分割，求得各規則成分波之振幅及週期，並配以不同隨機初始相位建構多組不規則波的時序列，接著進行相關波浪統計分析與比較，以探討現今進行不規則波列造波的適切性。測試結果發現，擁有相同頻譜特性的不同波列，會有不同的波浪統計特性。基於不同的海岸工程問題，所需面對的波動特性皆有不同，例如港灣波動問題需留意與自然共振週期相近的成分波的波高，一般以示性波討論；結構物受力行為評估需要留意最大波的波高與週期；而結構物的穩定分析則需要了解連續大波的群波效應。因此，利用不規則造波來探討海岸結構物與波浪之間的互制行為時，如何選擇適當波列以符合實際物理現象與工程規劃設計需求，本文以利用線性規則成分波搭配不同隨機初始相位組合構成不同不規則波波列，並利用相關統計分析的方式作深入的探討。

關鍵字

水工模型試驗；斷面造波水槽；不規則波列

並列摘要

The suitability of the selected wave trains for irregular wave tests in a wave flume was evaluated, this study extends the researches of Chen (2004), Twu (2005), Lee (2011), and Tsai (2012) to explore the subject via hydraulic model test in a wave flume and numerical simulations of irregular wave trains. JONSWAP spectrum modified by Goda with different peak enhancement factor together with specific wave height and period and initial random phase shifts of component waves was engaged in the experiments. The results show that due to the random nature of irregular waves, the irregular wave train with the same spectrum still offer different wave characteristics which might cause different results, like largest wave force, maximum wave height or wave group of excess waves. Based on the engineering planning and design has its own specific wave condition to be considered, such as in harbor tranquility problem, the component wave frequency is sensitive; in wave force acting on coastal structure problem, the largest wave height/wave force and the response are evaluated. In structural stability problem, however, the response from the excess wave group with large wave height is the most important. Therefore, the suitable irregular wave train selected for experiment for engineering planning and design on different target problem should be evaluated beforehand to find the suitable results.

並列關鍵字

Hydraulic model test ； Irregular waves ； Wave flume

國際替代計量

斷面水槽不規則造波試驗之適切性研究

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