西安城市单拱封闭型林荫街谷行道树对小气候影响研究

发布时间：2018-06-26 20:09

本文选题：行道树 + “单拱”封闭型　；参考：《西安建筑科技大学》2017年硕士论文

【摘要】：高速的城市化和人口集聚造成的气候恶化与人们对户外舒适气候条件需求间的矛盾日益凸显。行道树作为减缓城市热岛和改善小气候的重要策略已被广泛强调,在夏季街谷建筑自身对太阳直射无法充分遮挡时,行道树对小气候的影响显得尤为重要,同时也为使用者对街谷相对舒适环境的选择提供更多的自由度。当前街谷行道树的研究大多集中在美观和绿化形式等方面,关于行道树对街谷小气候影响作用的量化研究较少。为研究“单拱”封闭型街谷林荫空间行道树的小气候功效与调节机制,本文以行道树作为研究对象。首先,对西安城市林荫街谷实地调研,总结归纳出西安市常用的25种行道树和6种林荫空间类型。阐述林荫空间的构成要素并对行道树这一要素进行深入研究,明确行道树的功效和影响因素。然后,将西安市25种常用行道树按照不同影响指标进行分类排序,总结出降温增湿较好的树种,同时对国槐、悬铃木2种典型树种的典型形态构建模型计算枝冠阴影比,得出夏季遮荫和冬季透阳较好的树形。最后,选择具有代表性和典型性的基本空间单元“单拱”封闭型街谷林荫空间进行实测和数据分析,从定量的角度验证行道树对街谷小气候的影响作用。对西安市行道树的研究得出,适应于西安地区气候特征的行道树应选择叶面积指数较大、蒸腾速率较强、树冠较厚、冠大荫浓的落叶乔木为宜,这类树种有悬铃木、国槐、樱花、元宝枫、栾树、玉兰;树形应选择长柱状杯形和开心形树冠形态。“单拱”封闭型街谷林荫空间实测分析表明,行道树冠下气温变化时段可分为升温段、高温峰段、下午和晚间的降温段以及凌晨的低温谷段。行道树真正意义上发挥降温作用是在上午升温段且最多可降1～7℃与郊区气象站温度相近。株高9～16m ,冠幅5.5～13m的行道树在单拱全封闭型林荫空间的降温效应优于单拱半封闭型林荫空间。行道树日间具有降温作用、夜间有保温作用,还可缓解夏季街谷热舒适、改善人体舒适等级。行道树树冠夏季能够遮挡太阳直射发挥良好的遮荫效应,两侧有建筑遮挡的东西向街谷,北侧行道树遮荫8～10h发挥主要遮荫作用,南侧行道树遮荫时间有限。南北向街谷,行道树在日中前后2～3h发挥主要遮荫且遮荫时长各4～5h。无论街谷走向如何,道路一侧或两侧均有建筑遮挡的单拱封闭型林荫空间,行道树树冠辐射成为调节日间街谷小气候的主导因素。本文通过对西安城市林荫街谷调研归纳出6种街谷林荫空间类型,通过基础理论研究和模型构建分析得出适应于西安气候特征的行道树品种与形态,为西安市行道树选种、选形提供参考,通过对“单拱”封闭型林荫空间实测分析得到行道树冠下气温变化的时段特征与作用机制,从量化的角度揭示了行道树对城市街谷的降温效应和遮荫效应并阐述原因,推动了相关理论发展且具有实践意义。
[Abstract]:The climate deterioration caused by high speed urbanization and population agglomeration has become increasingly prominent with people's demand for outdoor comfortable climate conditions. As an important strategy to slow down the urban heat island and improve the microclimate, the road tree has been widely emphasized. In the summer street buildings, the shadow of the street trees to the microclimate is the shadow of the sun directly exposed to the sun. It is particularly important to provide more freedom for users to choose the relative comfort environment of the street valley. The current research on street trees is mostly focused on the form of beauty and greening. There are few quantitative studies on the impact of street trees on the street Valley microclimate. The small climate effect and regulation mechanism of Tao tree, this article takes the road tree as the research object. First, it summarizes and summarizes the 25 kinds of street trees and 6 types of shade space in Xi'an city tree shady street valley. It expounds the elements of the shade space and studies the elements of the road tree, and makes clear the work of the road tree. Then, 25 kinds of common road trees in Xi'an are classified and sorted according to the different influence indexes, and the tree species with better cooling and humidification are summed up. At the same time, the tree crown shadow ratio is calculated for the typical morphological construction model of 2 typical species of Sophora japonica and campis tree, and the better trees in summer shade and winter are obtained. Finally, the choice has the generation of generation. A typical and typical basic space unit, "single arch" closed Street Valley, was measured and analyzed to verify the effect of the road tree on the street Valley microclimate from a quantitative point of view. In the study of the Xi'an street tree, the row tree which adapted to the climate characteristics of the Xi'an region should choose the larger leaf area index and the transpiration rate. The tree crown is thicker, the crown and the shade thickened deciduous tree are suitable. The tree species include campanum campanulata, Sophora japonica, cherry, Acer Acer, Luan tree and Magnolia. The tree shape should choose the long column shaped cup and the happy crown form. The cooling effect of the road tree in the morning and the low temperature Valley in the morning is that the road tree really plays a cooling role in the morning temperature rise section and can decrease 1~7 degrees to the temperature of the suburb weather station at most. The plant height is 9 ~ 16m, and the canopy of 5.5 ~ 13m in the canopy space of the single arch is better than the single arch and semi closed shade space. The road tree has a cooling effect during the day, and it has heat preservation at night. It can also relieve the heat comfort of summer street Valley and improve the comfort level of the human body. The tree crown of the road tree can block the sun's direct shade effect in summer. There are building blocks on both sides of the street Valley, the north side road tree shade 8 ~ 10h play the main shade effect, the south side road tree shades. Time is limited. North and South Street Valley, the road tree in the day and after 2 ~ 3H to play the main shade and shade of 4 ~ 5h. no matter how the street Valley direction, the road side or both sides have a single arch closed canopy space of building block, the canopy radiation of the road tree is the dominant factor in regulating the day street valleys. This article through the Xi'an urban forest The shade Street Valley survey summed up 6 kinds of street valley forest space types. Through the basic theory research and model construction analysis, the variety and form adapted to the climate characteristics of Xi'an were obtained. It provided reference for the selection of Xi'an street trees and the selection of the shape. The segment characteristics and mechanism of action reveal the cooling effect and shading effect of the street tree to the urban street valley from the quantitative point of view, and explain the reasons, which promote the development of the related theories and have practical significance.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU985.12;TU119

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