潮间带地区跨海大桥设计流速计算分析

Calculation and analysis of design current velocity for Lianyungang Haibin bridge in intertidal zone

在大桥设计中设计流速是一项重要参数,其预测的准确性事关桥梁的安全施工和安全运行。通常采用实测资料分析推求或数学模型计算两种预测方法。为确保跨海大桥施工和运行的安全性,需要对设计流速进行准确预测。利用数学模型预测工程区域可能最大流速是一种有效的方法。应用基于有限体积法的二维浅水方程和干湿边界处理技术,建立了工程海区的潮流数学模型,并结合实测资料进行验证。在此基础上,考虑了有无风浪作用的不同工况组合,计算分析得到潮间带地区大桥工程位置在不同重现期的设计流速,为桥梁设计和相关物理模型试验研究提供重要参数。计算分析结果表明,风浪对潮间带地区的流场影响较大,桥梁设计流速计算时应充分考虑这一关键因素,以此保证桥梁施工和运行安全。

As one of the important parameters in the design of the bridge, the design current velocity is closely related to the safety of the bridge construction and its safe operation. Usually two kinds of prediction methods including analysis by the measured data and calculation by a mathematical model are used in the engineering practices. In order to ensure the safety of the bridge construction and normal operation, it is necessary to accurately predict the design current velocity. It is an available approach to use the mathematical model to predict possible maximum current velocity in the construction area. Therefore the mathematical model calculating the tidal current in the engineering sea area is developed by use of 2D shallow water equation and wet/dry boundary treatment technique based on the finite volume method, and the model verification is carried out using the measured data. On this basis, taking account of combinations of different working conditions with and without wind and waves, the design current velocity for the bridge construction position in the intertidal zone at different recurrence intervals is calculated and analyzed, which has provided important parameters for the bridge design and physical model tests. The calculated and analyzed results show that the key factors such as wind and waves should be considered in calculating design current velocity for bridge construction because they would cause greater impacts on the flow field in the intertidal zone.