單點錨碇圓柱浮體欄柵的消波機制研究

Abstract

本文研究主要目的在於估算單點錨碇圓柱浮體在不同波浪狀態下，探討其消波性能。而其中以梁(2000)所設計的半封閉圓管來做為實驗的水工模型，理論計算方面以Morison公式為力分析的初步架構，再以黃(2002)所提出波浪通過單排直立圓柱堤時之透射率加以修改成波浪通過單排圓柱浮體時之透射率。理論及實驗有良好的一致性，結果顯示單排圓柱浮體中，入射波形尖銳度增加及相對水深減小時，透射率減小，消波性能較佳。其中多排圓柱浮體實驗中，發現相對排距的改變不太影響消波性能，而孔隙比的大小也會影響其消波性能，孔隙比越大時，消波性能較差，孔隙比越小時，消波性能較佳。根據多排實驗結果可以得知增加排數的確可以提高其消波性能，但隨著排數的增加時消波的變化量逐漸變小，顯示過多的排數並無太大的功用，不如以單排且孔隙比較小的方式來代替。

The purpose of this paper is to estimate the wave sheltering of single-mooring spar buoy fences for the sandy coast protection. The spar buoy was constructed by a semi-closed pipe, which was designed by Liang(2000),Huang(2002) proposed a theoretical solution for the transmission coefficient of a one-layer fixed cylinder fence. Following Huang’s equation, a modified one for a one-layer spar buoy fence is deduced. The porosity ,which is the ratio of the gap and buoy spacing As the porosity increases, the transmission coefficient will increase. Experimental results agree well with the modified equation. The transmission coefficient also decreases as the wave steepness increases and the relative depth decreases. For multi-layer spar buoy system, the transmission coefficient won`t be a function of relative layer spacing when layer spacing changes, and porosity will also effect transmission coefficient, with porosity increases and transmission coefficient will be increase, Furthermore,a multi-layer spar buoy has a little better sheltering affect than a single-layer one. For the economical reason, one-layer spar buoy with small porosity is recommended.