| 摘要: |
| 夏季东西走向的街道因长时间暴露于日照形成最不
舒适的行人环境，树木可提供树荫降低气温但也阻碍了局地
通风，然而，植树对行人热环境的综合影响尚不清楚。针对
城市高密度街区(LCZ 2类型)中东西走向的街道，开展行道
树绿化差异对行人热环境综合影响的定量计算与分析。结果
表明：1)树木对行人热环境的影响是非线性的，且在夏季白
天不同时段呈不同规律，街道树木覆盖率与树致平均行人气
温差异值之间存在如下关系：上下午非线性关系强烈，中午
则接近线性关系；2)当树木覆盖率小于50%时，树致行人气
温降低的梯度大，每增加10%树木覆盖率，行人高度平均气
温最高约降低0.26℃；树木覆盖率超过50%以后，植树带
来的热效益改善值减小，而且影响的时间窗口趋于中午附近
(11：00—14：30)；3)东西向街道内的各种植树方案都
对行人热环境产生正面影响，当树冠相互接触形成连续树荫
时，树致改善效应接近饱和，继续提高种植密度反而会产生
负面影响。考虑城市用地紧张，建议东西走向的街道，采用
可形成连续树荫的50%左右覆盖率的行道树绿化，以获得舒
适的行人小气候 |
| 关键词: 风景园林 行人热环境 树木覆盖率 天空可视因
子 树木绿化 数值模拟 |
| DOI： |
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| 基金项目: |
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| Difference of Pedestrian Thermal Environment in Summer Caused by Trees in the Deep East-West Street Canyon in Fuzhou |
| LIN Ding,WU Jun,LIU Yamin,DENG Zhuo,HAN Chaoshuai |
| Abstract: |
| East-west streets are exposed to the longest sunshine during
summer, which leads to the most uncomfortable pedestrian environment.
Trees can provide shade to reduce the temperature, but hinder the
local ventilation. However, the comprehensive effects of tree planting
on the pedestrian thermal environment are unclear. In this paper, the
quantitative calculation and analysis of the comprehensive impact of
street tree greening differences on the pedestrian thermal environment
are carried out for the east-west street in high-density blocks (LCZ 2).
The results show that: 1) The influence of trees on the pedestrian thermal
environment is nonlinear, and there are different laws during different
periods of the day. The relationship between street tree coverage ratio and
the tree-induced average pedestrian temperature variation is as follows:
the nonlinear relationship is stronger in the morning and afternoon, but
it approximates linearity at noon; 2) When the tree coverage ratio is
less than 50%, the gradient of pedestrian temperature reduction caused
by trees is large. For every 10% increase in tree coverage, the average
temperature of pedestrian height will decrease by about 0.26℃; while
it exceeds 50%, the thermal-benefit improvement value brought by tree
planting decreases, and its time window of influence tends to be near
noon (11:00-14:30); 3) Various tree planting schemes in the east-west
street have a positive impact on the pedestrian thermal environment.
When the tree crowns contact each other to form a continuous shade, the
tree induced thermal benefits is close to saturation, and the go-on increase
of planting density has a negative impact. Thinking over the shortage of
urban land, it is suggested that street trees with a coverage rate of about
50% that can form continuous shade should be greening the east-west
streets to obtain a comfortable pedestrian microclimate. |
| Key words: landscape architecture pedestrian thermal environment tree coverage ratio sky view factor tree greening numerical
simulation |
