【摘要】：三峽水庫運(yùn)用后改變了下游河道的水沙條件,下泄泥沙量大幅減少,相應(yīng)水庫下游彎曲分汊河道的演變過程也會作出響應(yīng),對防洪、航運(yùn)、岸線利用等方面可能產(chǎn)生影響。因此,開展彎曲分汊河道水沙運(yùn)動與河床演變耦合機(jī)理研究具有重要理論與實(shí)際意義。本文在總結(jié)了國內(nèi)外已有研究成果的基礎(chǔ)上,通過原型觀測資料分析、概化模型試驗(yàn)與理論闡釋相結(jié)合的方法,綜合研究了彎曲分汊河段的水沙運(yùn)動特性與河床演變規(guī)律,以及二者之間的耦合機(jī)理,預(yù)測了彎曲分汊河道的演變趨勢。本文開展的主要工作與取得的主要成果如下:(1)通過原型觀測資料分析與概化模型試驗(yàn),研究揭示了不同水流條件下彎曲分汊河道分流區(qū)、汊道段與匯流區(qū)的水面比降、斷面平均流速沿程變化、橫斷面流速分布、水流動力軸線、水流紊動強(qiáng)度及紊動能的變化規(guī)律。(2)在分析選取懸移質(zhì)水流挾沙力公式與利用實(shí)測資料檢驗(yàn)推移質(zhì)輸沙率公式的基礎(chǔ)上,結(jié)合不同年份監(jiān)利河段的河道地形、水沙資料和概化模型試驗(yàn)流速觀測數(shù)據(jù),闡明了不同水流條件下彎曲分汊河道懸移質(zhì)泥沙與推移質(zhì)泥沙運(yùn)動規(guī)律,探討了懸移質(zhì)含沙量分布與主流分布的異位現(xiàn)象。(3)通過原型觀測資料分析和概化模型試驗(yàn),分析揭示了不同水沙條件下彎曲分汊河道總體沖淤變化規(guī)律及分流區(qū)、汊道段、匯流區(qū)的演變規(guī)律,探討了彎曲分汊河道主支汊移位的演變模式。(4)通過彎曲分汊河道的水沙運(yùn)動與河床演變之間的關(guān)聯(lián)分析,揭示了二者之間的耦合機(jī)理,并以監(jiān)利河段為例,預(yù)測了來沙減小條件下該河段的演變趨勢。
[Abstract]:After the operation of the three Gorges Reservoir, the water and sediment conditions of the downstream channel are changed, and the amount of sediment discharged is greatly reduced, and the evolution process of the bend and branching channel in the lower reaches of the corresponding reservoir will also respond, which may have an impact on flood control, shipping and shoreline utilization and so on. Therefore, it is of great theoretical and practical significance to study the coupling mechanism between water and sediment movement and river bed evolution in the curved branching channel. On the basis of summarizing the existing research results at home and abroad, through the analysis of prototype observation data and the method of combining model test with theoretical explanation, the characteristics of water and sediment movement and the evolution law of river bed in the curved braided reach are comprehensively studied in this paper. And the coupling mechanism between them, the evolution trend of the curved branching channel is predicted. The main work and results obtained in this paper are as follows: (1) through the prototype observation data analysis and generalizable model test, the study reveals the water surface ratio of the curved branching channel to the confluence region, the water surface ratio of the branching channel to the confluence region under different water flow conditions. The mean velocity of the cross section varies along the course, the velocity distribution of the cross section, the axis of water power, (2) on the basis of analyzing the formula of sediment carrying capacity of suspended flow and testing the formula of bed load transport rate with measured data, combined with the river channel topography of Jianli reach in different years, Water and sediment data and velocity observation data of generalized model test illustrate the movement of suspended sediment and bed load sediment in curved branching channel under different flow conditions. The heterotopic phenomena of suspended sediment concentration distribution and mainstream distribution are discussed. (3) through the analysis of prototype observation data and generalizable model test, the general scour and siltation variation law of curved branching channel under different water and sediment conditions, the distributary zone and the branching section are revealed. The evolution law of confluence area is discussed, and the evolution model of main branch shift of curved branching channel is discussed. (4) through the correlation analysis between the water and sediment movement of the curved branching channel and the river bed evolution, the coupling mechanism between the two is revealed, and the Jianli reach is taken as an example. The evolution trend of the reach is predicted under the condition of sediment reduction.
【學(xué)位授予單位】：長江科學(xué)院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TV147

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