阔叶林风场特性及风致动力响应的现场实测研究  

Measurement on wind field characteristics and wind-induced dynamic response in broadleaved forest

作　　者：辛大波 姜海新[1] 张洪福 XIN Dabo;JIANG Haixin;ZHANG Hongfu(College of Civil Engineering,Northeast Forestry University,Harbin 150040,China)

机构地区：[1]东北林业大学土木工程学院,哈尔滨150040

出　　处：《空气动力学学报》2022年第5期110-121,共12页Acta Aerodynamica Sinica

基　　金：中央高校基本科研业务费专项资金(2572019DF06);国家自然科学基金(51878131)。

摘　　要：强风对于单体树木和森林系统造成的损坏巨大,不可忽视。保障树木风致安全的首要问题是掌握强风下树木-风相互作用特性。特别是,树木的风致响应。基于此,以黑龙江帽儿山森林生态系统国家野外科学观测研究站的落叶阔叶林为研究对象,实测研究了三次强风时段的林间平均风与脉动风特性,分析了林中一棵白桦树的脉动风荷载及风致响应。研究结果表明:树木的扰动作用导致平均风随高度发生偏转,在冠层高度范围以内偏转梯度大,冠层高度以外偏转梯度较小;最大风偏转角度近似为67°。树木的扰动作用增加了冠层内风场的湍流强度,这一影响随着来流风强度的增加而增加。三次强风作用下,树木在脉动风作用下呈现出复杂的随机振动,振动响应的峰值频率与树木自由振动的峰值频率一致,与来流风的脉动风特性无关。阔叶树的机械传递函数的峰值频率与响应功率谱的峰值频率基本一致,树木风致响应的机械传递函数几乎与受迫阻尼谐振子的传递函数相同,这一点与针叶树具有相似的特征。The damage caused by strong wind to individual tree and forest systems is huge, which cannot be ignored. The primary issue to ensure the wind-induced safety of trees is to understand the characteristics of treewind interaction during strong wind, especially the wind-induced response of trees. For this reason, the deciduous broadleaved forest of the National Field Scientific Observation and Research Station of the Maoershan Forest Ecosystem in Heilongjiang was taken as the research object, and the characteristics of average and fluctuating wind of the forest during the three strong wind periods were measured and studied, as well as the fluctuating wind load and wind-induced response of a Betula platyphylla Suk in the forest were analyzed. The results show that the disturbance effect of trees causes the average wind to deflect with height of measurement point. The deflection gradient is large within the range of the canopy height, and the deflection gradient outside the canopy height is small. The maximum wind deflection angle is approximately 67°. The disturbance effect of the trees increases the turbulence intensity of the wind field in the canopy, and this influence increases with the intensity of the incoming wind. During the three strong wind periods, the trees exhibited complex random vibrations under the action of fluctuating wind. The peak frequency of the vibration response was consistent with that of the free vibration of the trees, and irrelevant to the fluctuating wind characteristics of the incoming wind. The peak frequency of the mechanical transfer function of broadleaved trees is identical with that of the response power spectrum. The mechanical transfer function of the wind-induced response of the Betula platyphylla Suk is almost the same as that of the forced damped harmonic oscillator, which is similar to conifer.

关 键 词：风-树相互作用 谱分析 强风 白桦 风致动力响应 

分 类 号：O32[理学—一般力学与力学基础] O35[理学—力学] TU973[建筑科学—结构工程]