波浪與複合結構物之交互作用

Abstract

根據二維線性波理論(linear wave theory)，利用邊界元素法(boundary element method)及有限元素法(finite element method)，來解析有關 波浪與防波堤之交互作用的問題。本研究探討之防波堤包含兩大類，一類 為拋石防波堤，另一類為複合式防波堤，而複合式防波堤，上部結構為彈 性沉箱，下部結構為可透水拋石堤或可透水拋石基礎。解析方法為將區域 畫分成含水區及彈性沉箱區，再將含水區域畫分成純流體區與可透水層區 ，在純流體區須滿足勢能流理論(potential flow theory)，在可透水層 區則須遵守達西定律(darcy's law)，再依線性波理論，並配合線性化的 動量方程式與邊界條件，第一類問題僅利用邊界元素法解析，而第二類問 題則將邊界元素法及有限元素法結合解析，探討交互作用的問題。本文目 的在探討影響防波堤安全的各種因素並瞭解各影響因素的重要性，除了探 討相對水深及入射波高對防波堤穩定性的影響，也探討堤身幾何形狀對堤 身安全的評估，而防波堤，下部結構(即透水拋石堤)之孔隙率及比滲透係 數也是重要影響防波堤安全的因素，本文對於拋石基礎之孔隙率及比滲透 係數引致波浪的變形，波力的變化，以及對於防波堤穩定性的影響等，作 了很詳細的研究分析。 Based on a two dimensional linear water wave theory, boundary element method (BEM) and finite element method (FEM) are developed and combined tostudy the interaction of water waves with breakwater. The breakwater includestwo main types. One is mounded breakwater, the other is composite breakwater.A composite breakwater includes two parts: a mounded base and a cassion locatedon the mounded base. Computational domain is separated to area including waterand area of elastic cassion. Furthermore, the water area divided to pure waterregion and permeable region. Potential theory is applied to pure water region,and the water motion in permeable region must satisfy Darcy's law. Areaincludind water is modeling by BEM, elastic cassion is modeling by FEM. The interaction problem will be solved by combined BEM and FEM. The aim of this report is to evaluate factors which effect the satefy ofbreakwater. There factors include wave condition, scale of cassion, andporosity and intrinsic permeability of mounded base.