山溪型河道桥梁阻水关键参数的仿真计算分析

Simulation and Analysis of Key Parameters of Water Blocking Causes of Bridge in Mountain River

为分析多孔拱桥阻水特性,采用一维水动力模型和三维模型结合方式计算桥梁壅水水面线。首先利用一维模型计算较大范围河道水面线,再以一维模型成果为边界条件,构建桥梁附近小范围河道三维模型,通过不同流量工况计算,分析桥梁壅水成因。结果表明:流量、Fr数与桥梁壅水高度呈正相关;桥梁尾流的湍流强度也受流量影响,流量越大,湍流强度越大,桥梁壅水也越高;通过改变桥梁阻水的关键因素Fr数,可以减少桥梁阻水作用。

To analyze the water blocking characteristics of open spandrel arch bridge, one-dimensional hydrodynamic model and three-dimensional model are combined to calculate the water surface profile of mountain stream channel. Firstly, one-dimensional model is used to calculate the water surface profile in a large scale, and then one-dimensional model results are used as boundary conditions, and three-dimensional model of some river reaches near the bridge is used to calculate different flow conditions, to analyze the causes of bridge backwater. The results show that the discharge and Fr number are positively correlated with the backwater height caused by the bridge;the turbulence intensity of the bridge wake is also affected by the flow rate;the greater the flow rate is, the greater the turbulence intensity, and the higher the backwater caused by the bridge;by changing the key factor Fr number of bridge water resistance, the water resistance effect of bridge can be reduced.