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橋墩密布的城市河道壅水高度及防洪對(duì)策研究

發(fā)布時(shí)間:2018-06-26 20:25

  本文選題:串列橋墩 + 尾流虧損。 參考:《中國(guó)海洋大學(xué)》2014年碩士論文


【摘要】:隨著沿河快速路的修建,使得越來越多的城市河道主槽內(nèi)或一側(cè)均修建了順?biāo)鬟B續(xù)分布的橋墩,嚴(yán)重?cái)D壓了河道的行洪斷面,造成較大壅水和流速分布的不均勻化,這勢(shì)必對(duì)河道行洪與河岸防護(hù)造成嚴(yán)重威脅。 國(guó)內(nèi)外眾多學(xué)者對(duì)單個(gè)橋墩和雙圓柱周圍水流結(jié)構(gòu)和圓柱繞流現(xiàn)象有著較為深入和全面的研究;在橋墩壅水方面,前人研究的內(nèi)容主要圍繞正交橋墩和斜交橋墩進(jìn)行。然而,但對(duì)于串列橋墩尾流現(xiàn)象及其產(chǎn)生的壅水,尤其是城市河道帶狀串列橋墩引起的流速虧損和壅水計(jì)算,目前尚無(wú)計(jì)算公式和科學(xué)合理的評(píng)判方法,更無(wú)相應(yīng)的技術(shù)控制標(biāo)準(zhǔn),尚屬空白。 本文在前人研究的基礎(chǔ)上,對(duì)串列橋墩尾流及壅水問題進(jìn)行了比較系統(tǒng)的研究,在理論分析、物理模型試驗(yàn)以及數(shù)值模擬方面開展了新的探索。 在理論研究方面,推導(dǎo)基于尾流尾渦疊加原理的串列橋墩尾流沿程最大虧損流速公式及尾流區(qū)橫斷面流速虧損公式,并建立滿足工程計(jì)算精度的壅水高度半經(jīng)驗(yàn)半理論公式;在物理模型試驗(yàn)方面,利用ADV流速儀和水位測(cè)針測(cè)得不同工況下串列橋墩尾流流速分布及墩前壅水高度;在數(shù)值模擬方面,利用CFD軟件FLOW-3D建立了串列橋墩的三維水動(dòng)力數(shù)學(xué)模型,探討了串列橋墩繞流流態(tài)的變化規(guī)律,分析墩后尾流流場(chǎng)分布及墩前壅水高度,并利用模型試驗(yàn)結(jié)果進(jìn)行了驗(yàn)證,結(jié)果吻合良好。 針對(duì)上述研究結(jié)果,本文提出橋墩密布城市河道的防洪對(duì)策:在保證工程合理性和安全性的基礎(chǔ)上,應(yīng)盡可能縮小橋墩間距,并減少建于河道中的橋墩數(shù)量和橋墩直徑,對(duì)于洪水期來流流速增大而導(dǎo)致的墩前沖高變大,應(yīng)當(dāng)充分考慮橋墩受沖高影響的受力情況,增加墩身強(qiáng)度和保護(hù)。
[Abstract]:With the construction of the expressway along the river, more and more piers with continuous distribution of water flow are built in the main channel or one side of the urban river channel, which seriously compresses the flood discharge section of the river, resulting in a large backwater and uneven velocity distribution. This is bound to be a serious threat to river flood discharge and river bank protection. Many scholars at home and abroad have a deep and comprehensive study on the flow structure and flow around a single pier and a double cylinder. In the backwater of piers, the previous studies mainly focus on orthogonal piers and skew piers. However, for the wake phenomenon of tandem piers and the backwater produced by them, especially for the velocity loss and backwater calculation caused by strip piers in urban river channels, there is no calculation formula and scientific and reasonable evaluation method at present. There is no corresponding technical control standard, which is still blank. On the basis of previous studies, this paper makes a comparative and systematic study on the wake and backwater problems of tandem piers, and makes a new exploration in theoretical analysis, physical model test and numerical simulation. Based on the theory of wake superposition, the formula of maximum loss velocity along wake and cross-section velocity loss in wake region of tandem bridge pier is derived, and the semi-empirical and semi-theoretical formula of backwater height is established to meet the engineering calculation accuracy. In physical model test, ADV velocimeter and water level needle are used to measure the velocity distribution of wake flow and the backwater height in front of the piers under different working conditions, and in the aspect of numerical simulation, Using CFD software FLOW-3D, the three-dimensional hydrodynamic mathematical model of serial piers is established, and the variation law of flow state around serial piers is discussed. The distribution of flow field at the rear end of piers and the backwater height in front of the piers are analyzed, and the results of model tests are used to verify this model. The results are in good agreement. In view of the above research results, this paper puts forward the flood control countermeasures for the urban river course with dense piers: on the basis of ensuring the rationality and safety of the project, the distance between the piers should be reduced as far as possible, and the number of piers and the diameter of the piers built in the river should be reduced. When the flow velocity increases during flood period, the pier's forward impact height should be increased, and the strength and protection of pier body should be increased by taking full account of the force of pier affected by the impact of scour height.
【學(xué)位授予單位】:中國(guó)海洋大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2014
【分類號(hào)】:TV87;U442.3

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