打樁噪音減噪系統模擬與實作研究

Simulation and Implementation of pile driving noise mitigation system

石久寬(Chiu-Kuan Shih)

指導教授 ： 陳琪芳

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202000538

摘要

近年來政府積極推動綠色能源，而台灣西部沿海具有絕佳的風力潛能，極具開發離岸風場之價值，風力發電進而成為重點發展的項目。然而離岸風機建置時產生巨大之低頻噪音，可能嚴重影響海洋哺乳類的生態，需在打樁施工時進行噪音隔離或採用降噪措施，減輕離岸風場開發對於海洋生態之衝擊。本研究使用相較於傳統氣泡幕更加穩定之氣球幕進行減噪研究，利用有限元素法在頻域下模擬打樁聲源並加入氣球幕減噪，進行打樁噪聲的預估，分析可能之減噪效益並透過反傅立葉轉換至時序列計算聲曝值結果，以台灣西部海域21號示範風機為模型進行模擬計算，建立一結合噪聲預估及減噪預測之數值模型。
由於在實海域佈放氣球幕時並無相應之減噪工法，造成氣球幕減噪技術無法在實際應用層面上發揮其價值，本研究針對氣球幕減噪技術進行研究，致力於建構氣球幕減噪工法雛形。進行簡易氣球幕減噪模組開發設計之研究，利用多層窗型結構之設計，調整其角度改變氣球在水中之排列方式，進而改變其體積分率以達到提升減噪效果之功效，並進行水槽實驗利用水下麥克風及音鼓進行減噪模組之實際測試及有限元素模擬計算，分析其在打樁噪聲能量集中的160Hz-500Hz頻率的減噪效果，並比較在相同氣球數目下體積分率對減噪效益之影響。

關鍵字

有限元素分析 ； 打樁噪音 ； 減噪效益 ； 氣球幕

並列摘要

In recent years, the international community has actively promoted green energy. As wind power has become one of the major development projects, piling noise has also become an important research topic. In this study, a finite element (FE) model was built using COMSOL Multiphysics software to calculate the sound field of piling noise. In Taiwan, coastal waters suitable for developing offshore wind energy are close to the main habitats of endangered marine mammals. Piling produces huge low-frequency noise that may seriously affect the ecological environment. In addition, underwater noise regulations and monitoring standards must be observed during construction. This study combines noise mitigation techniques (balloon curtains) to create an integrated piling noise prediction and mitigation system. The results show that the piling noise can be successfully predicted in the finite element model and also the effect of the mitigation system.
In order to make the balloon curtain noise mitigation technology show its value in actual piling construction. This research is committed to building the prototype of the balloon curtain noise mitigation method. Develop and design a simple balloon curtain noise mitigation module, use a special structural design to change the arrangement of balloons in the water, and then change its volume fraction to improve the effect of noise mitigation. Through water tank experiments and finite element simulation analyze the benefit of the noise mitigation module at the frequency 160Hz-500Hz, and compare the effect of different volume fractions on the noise mitigation benefit under the same number of balloons.

並列關鍵字

Finite Element ； Pile Driving Noise ； Noise Mitigation ； Balloon Curtains

參考文獻

[1] "4Coffshore", http://www.4coffshore.com/windfarms/windspeeds.aspx.

[2] 新聞傳播處(民108年06月14日)。"推動風力發電4年計畫—潔淨能源 乘風而起"。行政院，2019，取自https://www.ey.gov.tw/Page/5A8A0CB5B41DA11E/ef93b5c1-85ea-4b5f-ac55-f460d9204258。

[3] 周蓮香，邵廣昭，邵奕達。"中華白海豚族群生態與食餌棲地監測"。105 年度行政院農業委員會林務局委託研究計畫，2016。

[4] NOAA Technical Memorandum NMFS-OPR-55, "Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing - Underwater Acoustic Thresholds for Onset of Permanent and Temporary Threshold Shifts", 2016.

[5] 王煒傑。"離岸風機打樁噪音量測及減噪機制研究"。臺灣大學工程科學及海洋工程學研究所學位論文，2016。