山区峡谷悬索支撑输电结构处风场实测与风振响应研究

RESEARCH ON WIND FIELD MEASUREMENT AND WIND-INDUCED VIBRATION RESPONSE OF THE SUSPENSION-BRACED TRANSMISSION STRUCTURE IN MOUNTAINOUS GORGE

  • 摘要: 山区峡谷风场受地形影响较为显著,其风场特性颇为复杂,此将对跨越山区峡谷的悬索支撑输电结构风振响应产生较为显著的影响。鉴于此,获得峡谷风场特征进而研究其对悬索支撑输电结构风振的影响,是开展相关研究的首要环节。该文对某悬索支撑输电结构所处的峡谷风场进行了现场实测,基于实测数据研究了峡谷风场的平均风特性和脉动风特性并拟合了实测风谱。结合峡谷风场特性,发展了悬索支撑输电结构的风致振动分析模型。借助该数值工具,定量揭示了峡谷风场对此类结构响应的作用规律。结果表明:平均风速较小的样本风向分布较为离散,而平均风速不低于8 m/s的样本(强风样本)风向较为集中,强风样本风攻角与风向角的相关性较为显著;顺风向、横风向与竖向紊流强度均值分别为0.25、0.20和0.15,实测功率谱密度的谱值比理论谱更高,且其在高频段出现了回升现象;相较于规范风谱模拟风场,峡谷风场中的导线跨中侧向位移均值和均方差分别增大了3.16%和3.26%,其竖向位移均值和均方差则分别增大了7.85%和6.62%;在峡谷风场作用下,支撑导线悬索侧向位移响应的统计量(均值和均方差)与规范风谱模拟风场较为接近,而其竖向位移均值和均方差则分别增大了62.14%和15.28%。

     

    Abstract: The wind field in mountainous gorge is significantly affected by terrain, and its characteristics are quite complex, which has a significant impact on the wind-induced vibration response of the suspension-braced transmission structure crossing mountainous gorge. In view of this, obtaining the characteristics of the canyon wind field and thereby investigating its impact on the wind-induced vibration of the structure constitutes the essential first step in the related research. The gorge wind field where a suspension-braced transmission structure is located was investigated via a field measurement at first. Based on measured data, the mean and fluctuating wind characteristics of the wind field were analyzed, and the measured power spectrum was fitted. By incorporating the characteristics of the canyon wind field, a wind‑induced vibration analysis model for the suspension‑cable‑supported transmission structure is developed. With this numerical tool, the effects of the canyon wind field on the responses of the structure are quantitatively revealed. The results show that: The distribution of wind direction samples with lower mean wind speed is more discrete, while for samples with mean wind speed of no less than 8 m/s (i.e., strong wind samples), the wind direction is more concentrated. The correlation between wind attack angle and wind direction angle of strong wind samples is significant. The mean values of the turbulence intensities of longitudinal, lateral and vertical are 0.25, 0.20 and 0.15, respectively. The measured power spectrum has higher spectral values than the theoretical spectrum, and it appears to be higher in the high-frequency range. Compared with the wind field simulated by the theoretical spectrum, the mean and mean square deviation of midpoint lateral displacement of the conductor in the gorge wind field increase by 3.16% and 3.26%, respectively, while the mean and mean square deviation of vertical displacement increase by 7.85% and 6.62%. Under the canyon wind field, the statistics (mean and mean square deviation) of the lateral displacement response of the supporting‑conductor suspension cable are relatively close to those obtained from the wind field simulated with the standard wind spectrum, while the mean and mean square deviation of vertical displacement increase by 62.14% and 15.28%, respectively.

     

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