桥台局部冲刷的影响因素研究

发布时间：2018-04-25 02:24

本文选题：局部冲刷 + 影响因素　；参考：《北京交通大学》2014年硕士论文

【摘要】：桥台局部冲刷是造成桥梁基础破坏的重要原因之一。本文以Fluent软件为平台,采用水深平均的平面二维模型对桥台冲刷的影响因素进行了研究。研究模拟得到了桥台周围的流场,结合水流结构与紊动与冲刷的关系分析各因素对冲刷的影响。得出了以下主要研究结论： 1)压缩比增大时,流场中最大流速的位置不变,其大小随压缩比的增大而增大。与之对应,最大冲深的位置不变,最大冲刷深度随压缩比的增大而增大。压缩比小于20%时,冲刷主要表现为局部冲刷；压缩比大于20%,将出现一般冲刷,与局部冲刷并存,冲刷深度随压缩比的增大而增大。回流区的长度大概是桥台长度的7-8倍； 2)桥台宽度的增大改变了桥孔内流场的分布,压缩了桥台下游冲刷区域的范围。当桥台宽度足够大时,桥台下游就不存在冲刷的区域,只有淤积的区域； 3)一定阶段内,桥孔内涡涡长随着桥台宽度的增大而增大。孔内涡有最大值,当桥台宽度大于该最大值时,桥孔内涡长不再随着桥台宽度的增加而改变； 4)桥台挑角影响桥台下游回流区长度,总结并改进了计算回流区长度的公式,认为桥台正交时冲刷深度最大； 5)对各因素进行了多元回归分析,得到各因素对最大冲刷深度的贡献指数。
[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.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U442.32

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