环翼式桥墩周围水力特性试验研究

Experimental Research on Hydraulic Characteristics of Local Scour Around the Ring-Wing Pier

为分析环翼式桥墩周围水流流速分布特征,根据桥墩局部冲刷机理,进行了三种流量、三种水深、三种挡板位置的模型试验。试验结果表明:桥墩周围的表层纵向流速、表层横向流速仅仅受到水流波动的影响。挡板与河床的距离越小,桥墩中心线上的近底纵向流速越大,中心线上及墩侧一定范围的近底横向流速越大,但是近底垂向流速却越小。当挡板距离河床底部为0.3倍水深时,靠近河床边壁处各向流速受挡板影响不大,但是靠近桥墩中心处各向流速在挡板所在位置都有尖点,同时,靠近桥墩中心处的纵向相对紊动强度在测点高度与水深比值为0.4处有极大值。

A lot of experiments were carried out to analyze velocity distribution characteristics around the ring-wing pier. The experiments were de-signed for three kinds of flow velocities,three kinds of water depths,three kinds of baffle locations. The mechanism of local scour around bridge piers was its basis. The experimental results show that the surface’s lengthways velocity and surface’s crosswise velocity are only affected by fluctuation of flow. With the decrease of distance in the baffle and the bed,the bottom’s lengthways velocity and bottom’s crosswise velocity were greater and grea-ter,while the bottom’s vertical velocity was opposite. When the distance between baffle and riverbed is about 0. 3 times of water depth,near the river bed wall there had a little influence and near the bridge pier center there had sharp points in the position of baffle. Meanwhile,near the bridge center there had the maximum value on lengthways turbulence intensity when the ratio of height and depth of the measuring point is 0. 4.