塔基建设对蓄滞洪区洪水演进影响评价——以蒙西—天津南输变电工程为例

Evaluation of impact from tower foundation construction on flood routing of flood detention basin——A case study on West Inner Mongolia to South Tianjin Power Transmission and Transformation Project

为研究特高压输电线路的塔基建设对蓄滞洪区洪水演进的影响,以一、二维非恒定流方程为基础,建立了一维河道嵌套于二维大清河系蓄滞区的洪水演进数学模型。应用该模型模拟了工程建设前后的洪水淹没过程,同时对塔基所在网格按照工程建设前后的12个方案进行局部加密计算。结果表明:计算结果与实测洪水资料的洪水到达时间、峰现时间相差在1%以内,表明模型可靠;工程建设前后的洪水演进过程、淹没范围、最大水深分布、流场分布基本相同;塔基建设对水位影响不大,产生的最大壅水为0. 022 m,但是对局部流速影响较大,最大减少0. 545 6 m/s,占建设前流速的56%,造成冲刷深度达1. 3 m;塔基建设对200年一遇洪水的流速减小量是100年一遇洪水的2. 5倍,圆-方柱塔基对局部水流形态的影响是圆柱式的2倍。研究成果可为评价塔基建设对蓄滞洪区的防洪影响提供参考。

In order to study the impact from the foundation construction of the tower for ultra-highvoltagepowertransmissionlineon flood routing of flood detention basin,a floodrouting mathematical model of nesting one-dimensional river into two-dimensional flood detention basin of Daqinghe River System is established on the basis of one-dimensional and two-dimensional unsteady flow equations.The flood inundation processes before and after the construction of the project are simulated with this model,while the local refined calculations are made on the meshes where the tower foundations are located according to 12 schemes before and after the construction of the project.The result shows that the differences between both the calculated results of flood arrival time and peak appearing time and those of the measured flood data are within 1%,thus the model is verified to be reliable.The processoffloodrouting,inundated area,distribution of the maximum water depth,flow field distribution before and after the construction of the project are the same basically.The impact from the construction of tower foundation on water level is not so large with the maximum height of back-water of 0.022 m,however,which is larger on the local flow velocity with the maximum decrement of flow velocity of 0.545 6 m/s and the erosion depth of 1.3 m.The decrement of flow velocity of the flood with recurrence interval of 200 years caused by the impact from the tower foundation construction is 2.5 times of that caused by the flood with recurrence interval of 100 years,for which the impact from circular-square column on flow pattern is 2 times of that from the circular column.The study result can provide an idea for the evaluation of the impact from the tower foundation construction on the flood control within flood detention basin.