桥墩纵向间距对通航水流条件的影响研究

发布时间：2018-03-16 05:09

本文选题：连续桥墩　切入点：通航安全　出处：《长沙理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：桥梁建设在一定程度上影响了河道水流运动,在桥墩周围产生复杂的三维水流,致使桥墩附近存在不安全的航行区域。从通航安全考虑,有必要开展深入研究。利用flow-3D软件,针对不同来流角度以及连续墩不同间距,计算了圆形墩和圆端形墩周围的水流流场;通过概化船舶物理模型,研究了船舶通过单墩和连续墩时所受到的总力沿横向分力,确定了通航安全距离。得到以下主要结论:1.单桥墩周围存在两个明显的横向流速峰值,连续桥墩周围存在四个明显的横向流速峰值。桥墩尾部受到桥墩尾流的影响,横向流速出现正负摆动。随着连续墩间距的增加,第一个桥墩尾流的影响慢慢体现出来。桥墩附近横向流速零值,并不是在桥墩中心。第一个零值在第一个桥墩边壁附近,第二个零值出现在墩尾。桥墩周围的第一个峰值大小与单墩时很接近。第一个峰值和第二个峰值出现的位置与单墩时基本一致。当连续墩间距达到12D时,第三个峰值和第四个峰值与第二个桥墩的相对位置较单墩时基本一致。2.当水流流向与桥轴线法线方向的交角大于5°,不宜直接用横向流速为0.3m/s的标准确定桥墩紊流宽度,可采用有无桥墩横向流速差值作为紊流宽度的取值标准。水流流向与桥轴线法线方向的夹角和墩长对桥墩周围的紊流宽度存在明显影响。3.船舶经过单桥墩时,船舶所受总力的横向分力沿纵向分布曲线存在三个区,两个推力区和一个吸力区。当船舶经过连续墩时,当连续墩间距较小时,连续墩可以看做是一个整体,与单墩的分布规律基本相同。当连续墩间距为6D和9D时,吸力区发生分离,出现两个吸力峰值,当连续墩间距达到12D时,总力沿横向分力的分布规律与单墩相同,可以把连续墩看做是两个独立的桥墩。4.以横向流速0.3m/s为判别依据判别桥墩周围的安全通航距离。桥区安全通航距离为0.736D。将总作用力的横向分力峰值减小最明显的两断面中离桥墩较近的断面作为判别桥区安全通航的依据,可以得出桥区安全距离1.0D。两种依据判别的结果只是在数值上存在差异,但是连续墩对安全通航距离的影响规律一致。
[Abstract]:Bridge construction affects river flow movement to some extent and produces complex three-dimensional flow around the pier, which results in unsafe navigation area near the pier. Considering navigation safety, it is necessary to carry out further research. Using flow-3D software, it is necessary to carry out further research. The flow field around circular pier and round end pier is calculated according to different flow angles and spacing of continuous pier, and the total force of ship passing through single pier and continuous pier is studied by generalizing ship physical model. The main conclusions are as follows: 1. There are two obvious transverse velocity peaks around the single pier and four obvious transverse velocity peaks around the continuous pier. The tail of the pier is affected by the wake flow of the pier. The effect of wake flow on the first pier is slowly reflected with the increase of the spacing between the continuous piers. The zero value of the transverse velocity near the pier is not in the center of the pier. The first zero is near the side wall of the first pier. The second zero value appears at the end of the pier. The first peak value around the pier is very close to that of the single pier. The position of the first peak value and the second peak value is basically the same as that of the single pier. When the spacing between continuous piers reaches 12D, The relative position of the third peak value and the fourth peak value with the second pier is basically the same as that of the single pier. When the angle of flow flow direction to the normal direction of the bridge axis is greater than 5 掳, it is not appropriate to use the criterion of transverse velocity of 0.3 m / s directly to determine the turbulent flow width of the bridge pier. The lateral velocity difference of bridge pier can be used as the criterion of turbulence width. The angle between flow direction and normal direction of bridge axis and the length of pier have obvious influence on the turbulence width around pier .3.When a ship passes a single pier, There are three zones, two thrust zones and one suction zone in the transverse distribution curve of the total force on the ship. When the ship passes through the continuous pier, when the distance between the continuous piers is small, the continuous pier can be regarded as a whole. When the spacing of continuous piers is 6D and 9D, the suction zone is separated and two peak suction peaks occur. When the spacing of continuous piers reaches 12D, the distribution law of total forces along the transverse force is the same as that of single piers. The continuous pier can be regarded as two independent piers. The transverse velocity of 0.3 m / s is taken as the basis for judging the safe navigable distance around the pier. The safe navigable distance in the bridge area is 0.736 D. The section close to the pier in the two sections is used as the basis for judging the safe navigation in the bridge area. It can be concluded that the safety distance of bridge area is 1.0 D. the results of the two discriminations are only different in numerical value, but the influence of continuous piers on the safe navigable distance is the same.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.3;TV135.4

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