不同坡度单体山丘风速地形修正系数与越山风效应风洞试验研究

Study on Topographic Factor of Single Hill with Different Slope and Effect of Wind Flow over Hill by Wind Tunnel Test

为了研究不同坡度单体山丘风速地形修正系数与越山风效应对输电塔线结构的影响,对比了国内外5种规范取值与风洞试验测试结果,分析了不同坡度山丘山顶位置和迎、背、侧风坡面风速地形修正系数,并探讨了山丘风场竖向风速分量与紊流度变化特性.研究结果表明:5种规范中我国建筑结构荷载规范与高耸结构设计规范对不同坡度山丘山顶处的风速地形修正系数的取值最大;山顶位置风速地形修正系数并非完全随坡度增大而增加,坡度大于0.577之后达到1时,风速地形修正系数反而减小;现有的拟合公式计算山丘表面区域的侧风坡风速修正系数取值偏小,而计算上部区域的风速修正系数取值却明显偏大;山体坡度越大则竖向风速分量极大值反而越小,三类坡度山丘在迎风坡和背风坡测试的最大竖向风速分量与参考来流风速的比值分别为0.523和-0.542;山体坡度越大则表面紊流度越大,特别是陡峭山坡背风侧紊流度比较大,坡度为1时山丘背风侧0.6倍山体高度处的紊流度可高达35%.

In order to investigate the topographic factor of single hill with different slopes and the influence of wind flow over hill on transmission tower-line system,wind tunnel tests of three hill models with different slope were carried out and the results were compared with several different codes in China and abroad.The topographic factor at hilltop and along the hillside were analyzed,together with the vertical wind component and turbulence of wind field.The results show that the topographic factors at hilltop for different slopes are the largest in the Load code for the design of building structures and Code for design of high-rising structures.The topographic factor at hilltop does not always increase with the increasing slope of the hill,and it gradually decreases when the slope increases from 0.577 to 1.Additionally,The topographic factors of cross-wind at the surface of the hill calculated by the existing fitting formula are smaller than the measured ones,while the calculated values in the upper area are larger than the test one.Moreover,the maximum value of the vertical wind speed component decreases as the slope of the hill increases,and the ratios between the maximum vertical wind speed component and the inflow velocity are 0.523 and-0.542 for the windward and leeward side of the three types of slopes,respectively.The turbulence at the surface increases with the increasing slope of the hill,which is most obvious at the leeward side of steep hill.For example,when the slope is 1,the turbulence at the leeward side of the hill reaches to 35%at the 0.6 times height of the hill.