结构形式对桥墩局部冲刷三维性态发展的影响

Effect of pier structures on local scour 3D developments

选用基于动网格自更新技术的三维CFD冲刷模型,可以解决既有一维、二维计算研究方法的局限性以及准确性问题,对桥墩冲刷以及周边流场三维性态进行全过程动态跟踪分析.首先采用经典B.W.Melville实验环境以及实验数据,分别从流场、流速以及冲刷坑进行冲刷模型的准确性验证.进而利用该数值模型分别对3种典型桥墩(单柱墩、双柱墩、排墩)周边河床的冲刷深度、冲刷坑形态以及冲刷影响区域进行数值分析,通过数据分析得出各自完全不同的冲刷发展趋势与性态特征.通过对比分析可以看出,桥墩结构形式对桥墩局部冲刷三维性态发展有着显著影响,区分桥墩结构形式对桥墩冲刷设计、理论分析以及长期监测方案设置具有相当的必要性与重要性.

In the present study, a three-dimensional （3D） computational fluid dynamics （CFD） nu- merical model is applied to simulate the local bridge scour based on the dynamic mesh techniques, which solves the limitation and accuracy issues of the existing 1D and 2D methodologies. Using this model, the local scour 3 D Development process including the surrounding flow field can be traced in real time. The simulation accuracy is proved by comparing the numerical results to the measuring da- ta in the classic B. W. Melville experiment from the viewpoints of flow field, velocity, and scour hole. After that the scour depth, scour development pattern, and scour influence area are numerical- ly investigated under three different typical pier structures （shapes）. By conducting data analysis this simulation gives that different pier structures （shapes） result in totally different local scour results in- cluding developing trend and characteristics. It can be concluded that the effects of pier structures （shapes） on local scour 3D development is very obvious, which should be necessary and important in the scour design, analvsis and lon^-term monitoring.