應用聲學式振動管觀測接觸載輸砂量研究

Abstract

台灣位於多雨亞熱帶氣後區，常年多雨且地震頻繁，地形多為山高坡陡，流域面積狹小，且流量豐枯不均，上游水源不易保存利用。再加上台灣集水區之岩層較為年輕，抗蝕能力較弱，每逢颱風豪雨來襲或地震，鬆動的土層與高強度的降雨造成泥砂含量倍增，夾砂水流對河床或邊坡造成的淤積和沖刷，對於河川水情和治理以及水利工程構造物的興建都會造成許多影響。近年泥砂淤積和水濁度問題日益嚴重，因此水中泥砂含量之觀測十分重要，藉由長期記綠觀察泥砂資料作為依據，以分析研究出具備能準確、快速、在線(on site)及連續性(continuous)功能之泥砂觀測技術。 天然河道的泥砂觀測依輸送方式區分為推移載跟懸浮載，而推移載又以運動方式分成跳躍載以及接觸載，本研究主要針對接觸載之觀測進行試驗。以聲學原理為依據，傳統振動式測砂法理論為基礎，來探討滾動顆粒撞擊簡支式振動管之特性。建立簡支式振動管與能量曲線之相對關係；以不同坡度條件之顆粒作為標定，量測不同坡度顆粒撞擊振動管產生共振頻率間的變化關係，由資料擷取器讀值觀測撞擊強度大小，同時針對能量與坡度、粒徑數量間的關係，並進一步探討能量對應輸砂率之可行性。 振動管訊號透過頻譜分析圖可推估不同河川型態的推移載運動狀態及撞擊條件。振動管能量與撞擊條件的改變呈現良好的線性趨勢。若進一步對於振動管做深入研究，使振動管的應用技術更上一層，未來振動管可望成為推移載觀測的主流型式。

Abstract Natural river sediment observations divided by conveying the passage of time as set with the suspension set out, and goes on to set out the Youyi movement into jumping upload and exposure to upload, this study focused on the observation of the contact upload test. Acoustic principles as the basis for the traditional vibration measuring sand method based on the theory, to explore the characteristics of rolling particle impact simply supported vibration tube. The vibrating tube signal goes through spectrum analysis chart to estimate the different river types are set out the state of motion and impact conditions. The energy of the vibrating tube showed a good linear trend and impact conditions change. Further to do in-depth study of the vibrating tube, the application of the vibrating tube technology to an even higher level, the vibrating tube is expected to be the passage of airborne observations mainstream type.