發(fā)布時(shí)間：2018-04-25 02:24

  本文選題：局部沖刷 + 影響因素�。� 參考：《北京交通大學(xué)》2014年碩士論文

【摘要】：橋臺(tái)局部沖刷是造成橋梁基礎(chǔ)破壞的重要原因之一。本文以Fluent軟件為平臺(tái),采用水深平均的平面二維模型對(duì)橋臺(tái)沖刷的影響因素進(jìn)行了研究。 研究模擬得到了橋臺(tái)周圍的流場(chǎng),結(jié)合水流結(jié)構(gòu)與紊動(dòng)與沖刷的關(guān)系分析各因素對(duì)沖刷的影響。得出了以下主要研究結(jié)論： 1)壓縮比增大時(shí),流場(chǎng)中最大流速的位置不變,其大小隨壓縮比的增大而增大。與之對(duì)應(yīng),最大沖深的位置不變,最大沖刷深度隨壓縮比的增大而增大。壓縮比小于20%時(shí),沖刷主要表現(xiàn)為局部沖刷；壓縮比大于20%,將出現(xiàn)一般沖刷,與局部沖刷并存,沖刷深度隨壓縮比的增大而增大。回流區(qū)的長(zhǎng)度大概是橋臺(tái)長(zhǎng)度的7-8倍； 2)橋臺(tái)寬度的增大改變了橋孔內(nèi)流場(chǎng)的分布,壓縮了橋臺(tái)下游沖刷區(qū)域的范圍。當(dāng)橋臺(tái)寬度足夠大時(shí),橋臺(tái)下游就不存在沖刷的區(qū)域,只有淤積的區(qū)域； 3)一定階段內(nèi),橋孔內(nèi)渦渦長(zhǎng)隨著橋臺(tái)寬度的增大而增大�？變�(nèi)渦有最大值,當(dāng)橋臺(tái)寬度大于該最大值時(shí),橋孔內(nèi)渦長(zhǎng)不再隨著橋臺(tái)寬度的增加而改變； 4)橋臺(tái)挑角影響橋臺(tái)下游回流區(qū)長(zhǎng)度,總結(jié)并改進(jìn)了計(jì)算回流區(qū)長(zhǎng)度的公式,認(rèn)為橋臺(tái)正交時(shí)沖刷深度最大； 5)對(duì)各因素進(jìn)行了多元回歸分析,得到各因素對(duì)最大沖刷深度的貢獻(xiàn)指數(shù)。
[Abstract]:Partial erosion of abutment is one of the important causes of bridge foundation damage. In this paper, the influence factors of abutment scour are studied by using the plane two-dimensional model of water depth average on the platform of Fluent software. The flow field around abutment is simulated and the influence of various factors on scour is analyzed in combination with the relationship between flow structure and turbulence and erosion. The main conclusions are as follows: 1) when the compression ratio increases, the position of the maximum velocity in the flow field remains the same, and its size increases with the increase of the compression ratio. Correspondingly, the position of maximum scour depth is constant, and the maximum scour depth increases with the increase of compression ratio. When the compression ratio is less than 20, the scour is mainly local scour, and when the compression ratio is greater than 20, there will be general scour, coexisting with local scour, and the scour depth will increase with the increase of compression ratio. The length of the reflux zone is about 7-8 times as long as the abutment length. 2) the increase of abutment width changes the distribution of flow field in the bridge hole and compresses the range of erosion area downstream of abutment. When the abutment width is large enough, there is no scouring area downstream of abutment, only silt area; 3) in a certain period, the vortex length in the bridge hole increases with the increase of abutment width. When the width of abutment is larger than the maximum, the length of vortex in the hole will not change with the increase of abutment width. 4) abutment angle affects the length of downstream circumfluence zone of abutment. The formula for calculating the length of backflow zone is summarized and improved. It is considered that the depth of erosion is the greatest when abutment is orthogonal. 5) the multivariate regression analysis of each factor is carried out, and the contribution index of each factor to the maximum scour depth is obtained.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U442.32

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本文編號(hào)：1799347