城市高架桥桥阴光环境实测模拟分析

Light Environment Measurement,Simulation and Analysis of Shaded Green Space under Urban Viaducts

高架桥引发的景观及环境问题日渐显现,桥阴绿化作为缓解环境问题的途径依然存在绿化水平低、品种单一等突出问题,而光环境是限制桥阴植物生长最关键因素。文章选取武汉主城区的桥阴空间形态及光环境特征作为切入点,将光合有效辐射PAR及日照时长作为桥阴光环境衡量指标,利用照度仪进行监测,配合Ecotect Analysis软件对高架桥走向、桥体宽度高度之比(W/H)等变量进行模拟分析。结果表明:桥阴光照强度低于全日照的30%,光环境恶劣,受高架桥走向影响最大,W/H值次之;W/H值对不同走向的高架桥光照条件影响程度也不相同,相同的W/H变化幅度对南北走向的高架桥桥阴光照条件改善最大。基于此,结合植物适光性研究成果,提出桥阴植物设计策略,为桥阴空间等城市特殊灰空间绿化实践提供理论参考。

The landscape and environmental problems caused by viaducts are increasingly emerging.The greening of shade space under viaducts,which is a way to mitigate the environment problem,still faces the problem of low-level greening,less varieties used for greening,etc.,while light environment is the vital factor to restricting plant growth in the shade space under viaducts.This paper adopts the PAR and Sunshine Duration as the measurement indexes of light environment to use illuminance meter to monitor the form of shaded space under viaduct and the characteristics of light environment in the main urban area of Wuhan City,and combines it with Ecotect analysis software to simulate and analyze the viaduct trend,width height ratio(W/H),and other variables to light environment.The results show that the light environment is poor when the light density of shade space under viaduct is less than 30%of the total sunlight,and it is mainly influenced by the viaduct trend,followed by the width height ratio(W/H).The synergistic effects of different trends and width height ratios(W/H)to the light environment under viaduct are also different.Under the same change range of W/H,the light environment of the North-South viaducts is significantly improved compared with that of the East-West viaducts.Taking the research results of plant light adaptability into consideration,the paper comes up with the plant planning strategy of shade space under viaducts,which provides theoretic reference for the construction of urban special negative space such as shade space under viaducts.