【摘要】：沖積性河流中,橋梁的水害尤其是橋墩的局部沖刷幾乎不可避免。局部沖刷這種橋墩附近局部河床床面的下切現(xiàn)象,通常是由橋墩周圍水流的三維邊界層分離所產(chǎn)生的高強(qiáng)度的水流紊動(dòng)和旋渦體系所引起的,關(guān)系到橋梁基礎(chǔ)的穩(wěn)定。因此,橋梁設(shè)計(jì)工作者在進(jìn)行橋梁基礎(chǔ)設(shè)計(jì)時(shí),必須考慮采取一些防護(hù)工程對橋墩周圍的床面進(jìn)行護(hù)底防護(hù),以保證橋墩的安全與穩(wěn)定。迄今為止,橋墩局部沖刷的防護(hù)工程一直是防止河槽中橋墩周圍床面沖刷、橋墩失穩(wěn)和橋梁水毀的重要措施之一�，F(xiàn)有的橋墩局部沖刷防護(hù)工程措施都存在一些缺點(diǎn)和不足,在一定條件下,這些缺點(diǎn)和不足甚至?xí)l(fā)整個(gè)防護(hù)工程的潰敗,進(jìn)而影響橋墩的穩(wěn)定和橋梁的安全運(yùn)行。在護(hù)岸工程和堤防工程中表現(xiàn)突出的四面六邊透水框架群防護(hù)方法被提出用作橋墩局部沖刷的防護(hù),成為一項(xiàng)新型的橋墩局部沖刷防護(hù)措施�？茖W(xué)技術(shù)高速發(fā)展的今天,計(jì)算機(jī)技術(shù)的進(jìn)步給計(jì)算流體力學(xué)的發(fā)展帶來了契機(jī),復(fù)雜紊流場通過計(jì)算流體力學(xué)軟件進(jìn)行模擬的成果已逐漸得到行業(yè)認(rèn)可。運(yùn)用計(jì)算流體力學(xué)對四面六邊透水框架群的橋墩局部沖刷防護(hù)效果進(jìn)行模擬研究將是不同于以往傳統(tǒng)的沖刷防護(hù)研究的方向。本文在研究掌握橋梁水害形成原因的基本性質(zhì)基礎(chǔ)上,針對橋墩沖刷這一橋梁水害的最重要反映形式,深刻分析其產(chǎn)生機(jī)理,從水流結(jié)構(gòu)上認(rèn)識(shí)橋墩局部沖刷的形成過程;掌握數(shù)值模擬中與橋墩局部沖刷相關(guān)的控制方程和封閉方法,以及離散和邊界控制辦法等具體技術(shù)手段,然后對橋墩局部沖刷的四面六邊透水框架群防護(hù)數(shù)值模擬從以下方向展開:(1)對單個(gè)橋墩沖刷防護(hù)的研究。結(jié)合文獻(xiàn)中物理模型資料,在單墩周圍布設(shè)四面六邊透水框架群,建立三維數(shù)學(xué)概化模型,以非結(jié)構(gòu)化網(wǎng)格劃分方法,采用Fluent軟件進(jìn)行數(shù)值模擬,觀察分析模擬出來的水流流場和水流結(jié)構(gòu)情況。重點(diǎn)分析了四面六邊透水框架對形成局部沖刷的水流結(jié)構(gòu)以及水流速度的影響。(2)對群樁基礎(chǔ)沖刷防護(hù)的研究。結(jié)合包西鐵路大橋群樁基礎(chǔ)的實(shí)體尺寸,在其周圍布設(shè)四面六邊透水框架群,同樣建立三維數(shù)學(xué)模型進(jìn)行數(shù)值模擬,以流速為切入口分析四面六邊透水框架群對群樁基礎(chǔ)的防護(hù)效果。然后結(jié)合研究者對透水框架的理論探討和透水框架拋投防護(hù)在護(hù)岸護(hù)灘工程中的實(shí)際應(yīng)用經(jīng)驗(yàn),給包西鐵路大橋群樁基礎(chǔ)的具體防護(hù)提出了合理防護(hù)建議。
[Abstract]:In alluvial rivers, the water damage of bridges, especially the local erosion of piers, is almost inevitable. The local scouring of the local riverbed surface near the pier is usually caused by the high intensity turbulent flow and vortex system caused by the separation of the three-dimensional boundary layer of the flow around the pier, which is related to the stability of the bridge foundation. Therefore, in order to ensure the safety and stability of the bridge pier, the bridge designer must take some protective works to protect the bed floor around the pier in order to ensure the safety and stability of the bridge pier. Up to now, the protection of local erosion of bridge piers has been one of the important measures to prevent the erosion of the bed surface around the pier, the instability of the pier and the damage of the bridge water in the channel. The existing measures for partial scour protection of bridge piers all have some shortcomings and shortcomings. Under certain conditions, these shortcomings and deficiencies may even lead to the collapse of the whole protection project, thus affecting the stability of the pier and the safe operation of the bridge. The four-sided and six-sided permeable frame group protection method, which is outstanding in bank protection and embankment engineering, has been proposed as a local scour protection for bridge piers, which has become a new protection measure for local scour of bridge piers. With the rapid development of science and technology, the development of computer technology has brought opportunities to the development of computational fluid dynamics. The results of complex turbulence field simulation by computational fluid dynamics software have been gradually recognized by the industry. Using computational fluid dynamics to simulate the local scour protection effect of bridge piers in the four-sided and six-sided permeable frame group will be different from the traditional research on scour protection. On the basis of studying and mastering the basic properties of the formation of bridge water hazard, aiming at the most important reflection form of bridge pier scour, this paper deeply analyzes its producing mechanism, and understands the formation process of local scour of bridge pier from the point of view of water flow structure. Mastering the control equations and closing methods related to local scour of bridge piers in numerical simulation, as well as concrete technical means such as discrete and boundary control methods, etc. Then the numerical simulation of four-sided and hexagonal permeable frame group protection is carried out from the following directions: (1) the study on the scour protection of single pier. Combined with the physical model data in the literature, a three-dimensional mathematical generalization model was established by placing a four-sided and six-sided permeable frame group around a single pier, and the numerical simulation was carried out by using Fluent software, using the unstructured meshing method. The simulated flow field and flow structure are observed and analyzed. The influence of the six-sided permeable frame on the formation of the local scour flow structure and the flow velocity is analyzed. (2) the study on the erosion protection of pile group foundation. Combined with the solid dimension of pile group foundation of Baoxi Railway Bridge, a four-sided and six-sided permeable frame group is arranged around it, and a three-dimensional mathematical model is also established to carry out numerical simulation. This paper analyzes the protective effect of four-sided and six-sided permeable frame group on pile group foundation with the velocity of velocity as the entrance. Then, based on the theoretical discussion of the permeable frame and the practical application experience of the throwing and throwing protection of the permeable frame in the bank and beach protection project, some reasonable protection suggestions are put forward for the concrete protection of the pile foundation of Baoxi Railway Bridge.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U442.32

【引證文獻(xiàn)】

相關(guān)碩士學(xué)位論文 前1條

1 儲(chǔ)昊;透空四面體擾流機(jī)理及冷連接加工方法[D];重慶交通大學(xué);2016年

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本文編號(hào)：2339688