滩区公路对水库下游游荡型河段洪水及整治工程的影响

Influence of Highway in Floodplain to the Floods and Training Works of the Wandering Reach in the Lower Reaches of Reservoir

在河漫滩建设公路可能对河流行洪及整治工程产生干扰,为了兼顾河漫滩开发与河道行洪安全,必须对拟建工程选线进行科学分析与影响评价。以黄河小浪底水库下游右岸河漫滩内拟建公路为例,借助水力学及河流动力学方法,首先研究了未来水沙条件下,公路涉及河段河床边界和控制断面洪水位的变化及预测确定方法;然后通过洪水数值模拟分析与冲刷计算,对有无工程建设的河道洪水位、河势变化及整治工程进行了研究。分析表明,滩区建路选线远离主槽、顺河道行洪方向布置,工程建设对漫滩大洪水的影响很轻微;预测未来25 a遭遇10000 m^(3)/s漫滩洪水时,因建路引起局部行洪影响概化为3个阈值:洪水位壅高不超过0.06 m,主流流速增值不到1.6%,控导工程局部冲刷增量最大为0.17 m。研究河段整治工程体系与洪水河势有较好的互适性,可以维持中小洪水河势稳定,漫滩大洪水依然保持原有河势不变,拟建公路没有对整治工程增添新的不利影响。这种多角度的综合评估方法适用于水库影响下的游荡型河段。

The construction of highway on the floodplain may interfere with the river flood and regulation engineering.In order to consider both the development of floodplain and the safety of river flood discharge,it is necessary to scientifically analyze and evaluate the route selection of the proposed project.Taking the proposed highway in the floodplain on the right bank of the lower reaches of Xiaolangdi Reservoir on the Yellow River as an example,with the help of hydraulics and river dynamics methods,this paper firstly studied the change and prediction method of flood level at the riverbed boundary and control section of the highway under future water and sediment conditions;Then,through flood numerical simulation analysis and scouring calculation,the flood level,river regime change and regulation works of the river with or without engineering construction were studied.The analysis shows that the road selection in the beach area can be far away from the main channel and arranged along the flood discharge direction of the river,and the impact of engineering construction on the floodplain flood is very slight;It is predicted that in case of 10000 m^(3)/s floodplain flood in the next 25 years,the impact of local flood discharge caused by road construction can be generalized into three thresholds:the backwater height of flood level does not exceed 0.06 m,the increment of mainstream velocity is less than 1.6%,and the maximum local scouring increment of control and guidance works is 0.17 m.The regulation engineering system of the studied river section has good compatibility with the flood river regime,which can not only maintain the stability of medium and small flood river regimes,but also maintain the original river regime in flood plain and large flood.The proposed highway has no new adverse impact on the regulation engineering.This multi angle comprehensive evaluation method is suitable for the wandering river section under the influence of reservoir,and can be used as a reference for the traffic development and construction of similar alluvial wide beach river section.