摘要
以镇巴至广安高速公路渠县北互通立交连接线2号大桥为工程实例,借助于MIKE21 FM模型及HEC-RAS模型,通过进行数值模拟和对比分析,对河道内的涉水建筑物对河道防洪流态的影响进行了研究,分别计算不同洪水频率条件下,河道中建桥前后,桥墩对河道行洪的影响,并将两种数值模拟成果与理论经验公式计算成果进行比较。通过计算比较分析,采用MIKE21 FM模型计算时,建桥后桥位上游水位壅高,流向变化较小,而流速增加值与流量成负相关;采用HEC-RAS模型计算时,水位壅高值小于MIKE21 FM模型,且无法分析整个流场的数值变化。在河道地形复杂或是所在河道防洪标准较高时,建议采用MIKE21 FM模型,并可采用HRC-RAS模型作为验证。经验公式与模型计算成果差距较大,陆浩公式计算得到的壅高值偏大,D’Aubuisson公式偏小。该研究成果可为实际桥梁工程设计及河道沿岸洪泛区防洪提供指导或参考作用。
With the aid of MIKE21 FM model and HEC-RAS numerical model, The 2nd Bridge of Qux County North Interchange Connecting Line of Zhenba-Guangan Freeway is taken as an example to analyze the influence of the fording buildings in a river channel on the flood flow control state of river through the numerical simulation and contrastive analysis. Under the circumstance of different flood frequencies, the influences of piers on the drawing-off floodwater in river are calculated before and after the bridge construction. Two numerical simulation results are compared with the calculation result of the theoretical empirical formulas. Through the calculation and comparative analysis, when the MIKE21 FM model is used for calculation, after the construction of bridge, the upper water level backwater at the bridge position is high and the flow directions are changed little. The increase in velocity is negatively correlated with flow rate. When HEC-RAS model is used for calculation, the high backwater value of water level is less than the MIKE21 FM model, and it is hard to analyze the numerical change of the whole flow field. If the river terrain is complex or the flood control standards of the river are higher, it is proposed to use the MIKE21 FM model, and the HEC-RAS model can be adopted as a validation. There is the remarkable discrepancy between the empirical formula and the model calculation. The high backwater value calculated by Lu Hao formula is rather large and the D’Aubuisson formula is rather small. The study results can provide the guidance and reference for the design of the actual bridge projects and the flood control of the flooding areas along rivers.
作者
孟如真
胡阳
王志华
张谧
MENG Ruzhen;HU Yang;WANG Zhihua;ZHANG Mi
出处
《城市道桥与防洪》
2022年第10期221-226,M0020,共7页
Urban Roads Bridges & Flood Control
