斜坡滑落體所生成之水波的數值研究

Numerical study of landslide-generated waves

黃瓊書(Chiung-Shu Huang)

指導教授 ： 詹益齊

國立臺灣大學/工學院/土木工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202000135

摘要

海嘯為一極端的自然現象，會帶給人類重大的衝擊與破壞。地滑(landslide)為海嘯產生的重大來源之一，近代已有不少地滑海嘯(landslide tsunami) 事件造成災害的歷史紀錄。地滑海嘯為一複雜之物理問題，牽扯到地滑的性質與運動機制，以及固體與水之間二相的交互作用。對於複雜物理問題之探討，常建立物理實驗模型進行分析。由於物理實驗常受到尺度與經費之限制，則藉由以數學理論所發展的數值模式來進行數值實驗的模擬。
本文定義三角形固體地滑的最大厚度距離 ，分析地滑幾何形狀之改變對於產生之波浪特徵的影響，以OpenFOAM數值模式為框架建立地滑海嘯數值實驗模型，並分析數值實驗之結果。本文第一部分以OpenFOAM數值模式之內建模組建立之地滑海嘯模型，模擬Heinrich (1992)所建立之地滑海嘯的物理實驗，將數值結果與實驗資料進行比較，驗證了OpenFOAM對地滑海嘯模擬的可行性；第二部分為數值實驗之研究，建立陸上型地滑海嘯實驗，並改變最大厚度距離 值，探討地滑之形狀因子對產生之波浪的影響。分析近場波浪特徵得到波浪最大振幅隨 增加呈線性遞減的趨勢，而最大振幅發生之位置與固體和水面的夾角有關。另外週期不受 改變而有所影響，而在近場處能量轉移比 隨 增加以指數形式衰減。在遠場之波浪振幅比 隨著 增加而有線性遞增之趨勢。

關鍵字

地滑海嘯 ； 地滑形狀 ； 數值模擬 ； OpenFOAM

並列摘要

The tsunami is an extreme natural phenomenon that will bring great impact and destruction to human beings. Landslide is one of the major sources of tsunami. In recent times, there are many historical records of disasters caused by landslide tsunami. Landslide tsunami is a complex physical problem, which involves the property and motion mechanism of landslide and the two-phase interaction between solids and water. To explore the complex physical problems, physical experiment models are often established for analysis. Due to the physical experiments are often limited by scale and funding, numerical models developed by the mathematical theory are used to do the numerical simulations.
This study defines the maximum thickness distance of a triangular solid landslide to analyze the influence of the change of the landslide geometry on the wave characteristics, and uses the OpenFOAM numerical model as a framework to establish a numerical experimental model of landslide tsunami and analyzes the results of the numerical experiments. In the first part of this study, the landslide tsunami model established by built-in function of the OpenFOAM numerical model was used to simulate the physical experiments of the landslide tsunami created by Heinrich (1992). The feasibility of landslide tsunami simulation is verified by comparing the numerical results with the experimental data. The second part is the study of numerical experiments. This study builds a subaerial landslide tsunami experiment, and discusses the influence of the shape factor of the landslide on the generated waves by changing the maximum thickness distance value. The results indicate that the maximum wave amplitude of near-field is linearly decreasing with the increasing . And the location of maximum wave amplitude is related to the angle between the solid and the water surface. Additionally, the wave period is not affected by the change of , and the near-field energy transfer ratio decays exponentially as the increases. The wave amplitude ratio at the far-field tends to increases linearly as increases.

並列關鍵字

landslide tsunamim ； landslide shape ； numerical simulation ； OpenFOAM

參考文獻

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