Research On The Morphology Of Urban Street Canyons Based On The Distribution Characteristics Of Fine Particles ——Take Changhuai Street In Hefei As An Example

With the development of China’s cities from quantity to quality,from existing to excellent,urban air quality has become a hot issue of social concern and an important field of human settlements research.As an important part of the city,street canyons are closely related to urban residents,and the fine particle pollution inside them is also the focus of the government and residents.Based on the needs of urban residents for a healthy built environment,this study took Changhuai Sub-district,Hefei,Anhui Province as the research object,analyzed the distribution characteristics of fine particles in the street canyons in winter and summer,and obtained the spatial form of the street canyons based on the distribution characteristics of particulate matter.At the macro,meso and micro levels,the design and optimization method of the street canyon space form under the guidance of air quality is proposed.The main conclusions are as follows:（1）The PM_2.5mass concentration in Hefei in winter presents a trend of"high in the northeast and low in the southwest".Changhuai and Zhan Street in Yaohai District are one of the areas with high concentrations of PM_2.5in Hefei.The air quality of the street canyons in Hefei City is good in summer.The average mass concentration of PM_2.5ranges from 15.28 to 63.70μg·m^-3,which is around the limit value of the first-class standard.level and secondary.（2）For the spatial distribution of different street canyons,the trend of PM_2.5mass concentration from large to small is:road intersection>roadside>community park green space>general street canyon.The higher the wind speed,the lower the PM_2.5mass concentration;the farther away from the pollution source,the lower the PM_2.5mass concentration;the closer to the green plants,the lower the PM_2.5mass concentration.Park green space,wide street canyons,lowering the building height on the windward side and increasing the street width can reduce the PM_2.5mass concentration inside the street canyon.The leeward side of the rising street canyon is prone to PM_2.5accumulation.（3）The concentration of fine particulate matter in the canyon of Changhuai Street,Hefei is significantly higher than that of the surrounding building environment.It is mostly distributed on Shengli Road in winter and on the west side of Shengli Road in summer.Non-essential commuters in the street canyon should avoid traveling during the afternoon rush hour on weekdays.They can choose to travel between 15:00 and16:00.At this time,the wind speed is high and the traffic flow is small,which can reduce the impact of PM_2.5on air quality.The purpose of this research is to provide a technical basis for the design and optimization of urban street canyons in the stages of urban planning and renewal,architectural design and renovation,and to explore a design method of urban block space form that is conducive to energy conservation and emission reduction,promoting healthy behaviors and improving air quality.Figure 39 table 20 reference 151...