Study On Distribution Of Velocity In Sea Channel

Xiushan Bridge is located in Zhoushan City, Guanshan Island and Xiushan Island .The velocity is often large at the bridge pier and narrow channel effect is significant The sea bed rock slope is so large that the velocity at sea bed is large and the bridge foundation construction is extremely difficult. It is of great significance to study narrow channel effect and velocity distribution on bridge construction. In this paper, the flow field of Xiushan Bridge is studied in detail based on tank test and numerical simulation.Firstly, the vertical velocity distribution in tank with convex bottom was studied.The experiment was carried out in the fine tank of Zhejiang University, and three kinds of glass convex bottom with triangular and trapezoid plus a flat bottom were laid at the bottom of the tank. A total of 21 sets of data were obtained according to the three kinds of flow. According to this, the parabolic vertical velocity distribution formula of is established. The analysis shows that the undetermined coefficient is related to the linear function of the convex surface gradient J, and the a and c decrease with the increase of J, b is on the contrary. The location of maximum flow velocity decreases with the increase of J,and the lowest is at relative water depth of 0.41,far away from the water surface. The ratio of the maximum flow velocity to the average velocity of the section is close to constant. The velocity distribution calculated in this paper is consistent with that of the tank test data, indicating that the formula objectively reflects the velocity distribution in open channel with convex bottom.Then, the flow field of Xiushan Bridge was simulated by Delft3D software, and the tidal level and velocity data of two stations were verified by field measurement.The results were good. The 5 bridge piers located at the south side of Xiushan Bridge were selected and 6 vertical lines per bridge pier. Through the numerical simulation,the velocity data of 30 vertical lines were obtained. According to this, the vertical distribution formula of the average dimensionless velocity during a tide circle is established. The analysis shows that the average dimensionless velocity during a tide circle of the 7 # ? 10 # piers increases with the increase of the relative depth, and the maximum is at the water surface. The average dimensionless velocity during a tide circle of the 11# piers decreases with the increase of the relative depth, and the maximum is at the sea bed. The above phenomenon is mainly related to the seabed slope. The maximum velocity of the high tide at 11 # piers near Guanzhan Island is significantly larger than that of the low tide. The maximum velocity of the low tide at 7 # piers near Xiushan Island is significantly larger than that of the high tide...