臺灣博碩士論文加值系統

堰塞壩之潰決促使水流洪峰流量上升，高能量之洪水挾帶大量泥砂一次性的向下游侵襲，泥砂大量淤積導致下游河床劇烈改變，對下游災區人民的生命財產造成重大的威脅與損害。透過中興大學惠蓀林場蘭島溪全國唯一的天然試驗渠道進行現地堰塞壩潰決試驗，觀測潰決歷程與現象。本研究除了使用水位計、電容式土壤含水量感測器及聲波都普勒流速儀等接觸式的儀器外，亦利用多台攝影機(非接觸式)之二維影像像素座標轉換成三維座標，直接性的觀測堰塞壩潰決現象，包含：(1)蓄水期間壩體的塌陷、破壞與壩體內部水份含量之關係；(2)潰決期間潰口表面流場變化，期望突破對現地堰塞壩觀測之技術。本研究分別於2016年11月7日(Test 1)及2017年4月24日(Test 2)進兩次現地試驗，Test 1為未經夯實之案例，Test 2為受自然夯實之案例。
兩次試驗發現壩體的夯實程度對潰決型態與水文歷程有相當的影響性，當壩體未經夯實壓密、結構鬆散，又蓄水時間較長時，下游坡面容易發生管湧破壞；於水文歷程的四個階段中，蓄水階段的影響因子有壩體夯實程度及地下水面，而入流量影響較小；滲流階段受到庫容大小及壩體夯實程度影響。透過三維影像分析有效量化壩體塌陷與水平位移量，發現壩體沉陷歷程皆以近似線性的趨勢下降。另外壩體夯實程度影響塌陷量之大小，卻不影響水平位移總量，且當壩體夯實程度低，壩頂及壩體結構鬆散、脆弱的區域容易產生較大的土體沉陷。本研究為第一個將三維粒子追蹤的技術應用在現地堰塞壩潰決之研究，該結果指出垂直流向速度占總體約32%，顯示二維質點追蹤不適合應用在潰決流場；最後將平均表面流速分為三個階段，第一階段：洪水下切侵蝕，出流量上升，表面流速增加；第二階段：洪水側向侵蝕，出流量保持高點，緩慢增加至尖峰流量，表面流速減小；第三階段：洪水溯源侵蝕，出流量下降，表面流速緩面增加至定值。成果顯示本技術的應用可使潰決機制的分析上更加精進。

Landslide dam breach releases large amount of water and sediments, which cause dramatic changes at the downstream channels and it poses significant risk to residents and properties located in the inundated area. Field experiments on dam failure were conducted to observe the breaching process. These were conducted on November 7, 2016 (Test 1) and April 24, 2017 (test 2) into two field experiments, test 1 is less compaction case and test 2 is a natural compaction case. This research used intrusive instruments such as pressure gauge, soil moisture sensor and Acoustic Doppler Current Profiler (ADCP). This study is a first of its kind that 3D-PTV was applied in the field dam failure. In addition, the dam subsidence and flow field of the cross section were quantified by a nonintrusive method — 3D coordinate translation analysis. Direct observation of the dam breach included; 1. The relationship between dam subsidence and the water content inside the dam during the period of impoundment 2. The change of the surface flow field during the breach period.
It is found that compaction has a significant effect on the breach type and hydrograph. The piping will occur at the downstream slope when the dam is less compacted and when impounded time is long. In the impoundment stage, compaction and the height of groundwater are the most influencing factors. In the seepage stage, the most significant factor is compaction and impounded volume. Through the 3D image analysis, the dam subsidence follow a linear trend. In addition, compaction affects the dam subsidence, but does not affect the horizontal displacement, and the crest and the region of weak structure have large subsidence. The study also revealed that the vertical velocity played an important role in surface velocity, the proportion is about 32%, which indicated that previously applied 2D-PTV or LSPIV is not applicable in the breach channel. Finally, the average velocity distribution is divided into three stages. During the first stage, there is flood down cut, discharge and velocity increase. In the second stage, lateral erosion occur, discharge remain constantly high and increases slowly to peak and velocity decreases. Finally, during the third stage, flood begins to head cut, discharge decreases and velocity increases slowly to constant value. The results show that the application of this technique can improve the accuracy in the dam breach process.

摘要 i
Abstract iii
目錄 v
表目錄 vii
圖目錄 viii
第一章 前言 1
1.1. 研究動機 1
1.2. 研究目的 3
1.3. 論文架構 3
1.4 研究流程 5
第二章 文獻回顧 6
2.1 堰塞壩潰決機制 7
2.2 影像分析 10
第三章 研究方法與試驗配置 16
3.1 研究區域概述 16
3.2 試驗配置與器材 19
3.2.1 試驗配置 19
3.2.2 試驗器材 20
3.3 試驗流程 24
3.4 三維影像分析 27
3.4.1 壩體塌陷 27
3.4.2 三維粒子流速追蹤 37
第四章 結果與討論 43
4.1 潰決歷程 43
4.2 壩體塌陷 51
4.2.1 Test 1 51
4.2.2 Test 2 57
4.3 3D-PTV 63
第五章 結論 69
參考文獻 71

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