Simulation And Optimization Of The Relationship Between Spatial Shape And PM_2.5 Concentration Of Residential Areas In Hefei City

PM_2.5 has a wide range of sources,wide spread and great harm,and has become the primary pollutant affecting the urban air quality in China.Living as the city’s primary function,improving the environmental quality of urban residential areas is of great significance to improving the overall living environment of the city.This paper takes the residential area of Hefei as the object,summarizes the spatial morphological characteristics of the residential area in Hefei City,and condenses the spatial morphological indicators of residential areas,discusses the relationship between spatial morphological indicators and PM_2.5 concentration in residential areas,and uses Envi-met software to simulate the spatial patterns of different residential areas.Based on the simulation results,the PM_2.5 concentration under the index is proposed to improve the PM_2.5 concentration in the residential area of Hefei City.Finally,the measures to improve the air quality of urban residential areas are proposed from the perspective of spatial shape optimization of residential areas.The paper firstly analyzes the relationship between urban pollutant distribution principle,air quality and urban spatial form,and tries to summarize the spatial morphological elements of residential area that affect PM_2.5 concentration,which is used as the residential area of Hefei City.Morphological indicators provide theoretical guidance.Secondly,the spatial morphological characteristics of the residential area in Hefei City is that the residential area of the old city belongs to the type of“low volume ratio and low green rate”,which is mostly in the determinant and point type;the residential area in the new city belongs to the type of“high volume rate and high green rate”.Most of the points.The spatial form indicators of residential areas include the residential group plane combination form,wind direction angle,sunshine coefficient,floor area ratio,and green space rate.Among them,the residential group plane combination form includes determinant,point type,peripheral type,hybrid type;the wind direction angle is set to 15,30,45,60,75,90 in turn;the sunshine coefficient is1.2,1.4,1.6,1.8,2 respectively.The plot ratio is 0.8,1.2,1.6,2;the green rate is 20%,25%,30%,35%,40%.Thirdly,the six residential areas in Hefei Old Town and Xincheng District were selected as the volume ratio comparison group,the green space rate comparison group and the traffic location comparison group as the measured objects.The relationship between the spatial shape index and the PM_2.5 concentration in the residential area was analyzed.The results show that the spatial form index green rate is inversely proportional to the PM_2.5 concentration,and the plot ratio is proportional to the PM_2.5concentration.The PM_2.5 concentration in the old city is higher than that in the new city.The temperature was negatively correlated with PM_2.5 concentration,humidity was positively correlated with PM_2.5 concentration,and wind speed was negatively correlated with PM_2.5 concentration.The regression equation analysis shows that the influence degree of climate elements on PM_2.5 concentration is from strong to weak:wind speed>temperature>humidity.Finally,Envi-met software is used to simulate the PM_2.5 concentration in different spatial forms of residential areas.Based on the simulation results,suggestions for improving the PM_2.5 concentration in residential areas of Hefei City are proposed,and the urban residential area air is improved from the perspective of spatial shape optimization of residential areas.Environmental quality measures.The results are as follows:The best way to plan the spatial combination of residential groups in residential areas in Hefei is determinant,followed by point group,mixed and peripheral is not conducive to PM_2.5 diffusion in residential areas;the optimal wind direction projection angle is 60 degrees.45 and 75 degrees are optional,15 degrees is not optional;the concentration of PM_2.5 in residential area gradually decreases with the increase of sunshine coefficient,and the optimal solution of solar radiation coefficient is 2,followed by 1.8;the overall space of residential area The PM_2.5 concentration in the living area gradually increases with the increase of the plot ratio of the residential area;the green space rate should be above 35%,in order to effectively alleviate the PM2.5 concentration in the residential area.For residential areas in the old city:the buildings enclosed or semi-enclosed in the residential area should be demolished;the layout orientation should be 15 degrees east of the north;appropriate removal of some buildings with higher density to improve the sunshine distance and reduce the floor area ratio The ventilation environment;the road planning should be large and should not be too bent;it is suitable for seeing green and flexible,adding point greening in the vacant area inside the residential area,mixing the three vegetation types of the shrub and grass,adding the roof outside the plane greening And the greening of the wall,the choice of evergreen vegetation or different vegetation during the green leaf period to combine planting;the selection of paving bricks with high water permeability and low reflectivity;and the formation of a large ring-shaped“blue-green space”and reasonable arrangement The layout of the two sides of the strait creates a good ventilation environment.For the residential area of the new city:refer to the old city.In addition,it is recommended to adopt the determinant in the future;increase the roof greening outside the plane greening;introduce the sea breeze into the city by arranging the arrangement of the buildings and the direction of the road.This paper analyzes the PM_2.5 concentration distribution in urban residential areas by using field monitoring and numerical simulation.This paper studies urban residential areas based on the knowledge of interdisciplinary studies such as urban and rural planning,urban climatology,urban environmental science,and building science and technology.The relationship between spatial morphological indicators and PM_2.5concentration,and the optimization of spatial morphological indicators in residential areas,is from the perspective of development mode,with the goal of convenient transportation,beautiful environment and local characteristics in residential areas.From the perspective of spatial form,improving the quality of the air environment in urban residential areas also provides a new perspective for the planning and design of residential areas.