钱塘江河口建桥对涌潮的影响研究

Effect of bridge engineering on tidal bore in Qiantang estuary

针对涌潮资源的保护问题，研究了桥梁工程对钱塘江涌潮的影响．基于河工模型的相似理论，从二维浅水方程推导出潮汐河口水流运动的相似条件．制作了钱塘江河口模型，并模拟了涌潮的形成与传播过程．通过河口模型研究了桥梁工程对涌潮的形成、形态与高度的影响，并根据模型试验数据建立了涌潮高度减小率的经验公式．结果表明，桥梁工程不会改变涌潮的形成．桥墩对涌潮形态的影响范围一般限于桥位上游300～500m．涌潮高度的影响程度主要取决于桥墩占据河道的截面积，截面积越大，桥位上游涌潮高度的减小值也越大．

For protecting the resource of the tidal bore, the effect of bridge engineering on the tidal bore was studied. Based on similarity theory of the physical model, the similarity condition of the current movement in the tidal estuary was deduced from the 2D shallow water equations. The Qiantang estuary model was established, and the formation and propagation process of tidal bore was simulated. The effect of bridge engineering on the formation, shape and height of the tidal bore were studied using the model, and an empirical formula for the decrease value of tidal bore height was constructed. The results show that bridge engineering does not affect the tidal bore formation, and that the influence range of piers on the shape is about 300-500 m upstream from the bridge site. The influence of the height mainly depends on the area of piers holding river cross-section, and the decrease value of the tidal bore height increases with increasing area.