Optimization Strategy Of Chongqing Urban Business Center Based On Wind Environment

Rapid urbanization has brought about rapid expansion of urban space.Due to the division of the main city by mountains and rivers,chongqing is short of land for construction.Dense building layout,complex terrain barriers and unbalanced green space structure further aggravate the city's calm wind climate,heat island effect and urban haze.Micro climate adaptability,however,the problem of insufficient more evident in chongqing central business district,central business district of chongqing for its development intensity big,building energy consumption,green land resources shortage,to large displacement ventilation haze and urban heat island effect is more significant,the problem of insufficient wind environment comfort has influence to people's health and comfort.Urban space is one of the important factors affect the wind environment design,wind environment design is to promote the spread of PM2.5(main pollutants of haze weather)important method,therefore,how to utilize the city space optimization to improve the wind environment of micro climate,ease worsening due to the urban construction ventilation smog problem,is now the urgent need of mountainous urban planning research and an important frontier science problem.In mountainous cities with obvious topographic differences and complex and changeable urban spatial structure,the elements of different scales of space are complex,resulting in greater differences in wind field and PM2.5 concentration distribution due to local circulation than that of plain cities.The problem of insufficient adaptability of wind environment varies greatly in local areas.In this context,it is urgent to seek the optimization strategy of mountain city space based on the micro-scale of wind environment,especially the commercial center with dense population and buildings.Papers to the central business district as an example,aims to build from the perspectives of planning systems thinking to solve the problem of urban wind environment,build based on PM2.5 diffusion,no wind and the wind comfort wind environment evaluation index,based on the microscopic scale space research,put forward the corresponding optimization strategy space,and using the method of CFD simulation and field measurement carried out empirical research,trying to case the quantitative evaluation of wind environment provides a new thought and method,optimization strategy and feasibility Suggestions,hope for mountain urban wind environment improvement,local fog haze of slow to make a beneficial exploration.The research is carried out according to the idea of "problem sorting-theoretical construction and analysis-strategy proposal-case verification".The paper begins to sort out the contradictions between the world and China's rapid urbanization,extensive land use development in mountainous cities,space of commercial center and microclimate environment,highlighting the urgency of research on spatial optimization strategy based on wind environment.Secondly,the evaluation index of the wind environment,the characteristics of the wind environment in chongqing,and the inadequate adaptability of the urban space and the wind environment are analyzed.Based on the human scale,this paper constructed the wind environment evaluation index of 1.5m pedestrian height based on PM2.5diffusion,quiet wind area and wind comfort,and summarized the characteristics of chongqing's wind environment,such as high static wind frequency,significant local circulation and severe static wind pollution.Then,the problems of inadequate adaptability of urban space and wind environment are analyzed,including prominent contradiction between human and land,insufficient high-density construction and open space,neglect of local microclimate in urban planning,design of breeze channel,and inadequate consideration of control index.Thirdly,the spatial development of the main city and the central business district,the characteristics of the central business district of chongqing and the inadequate adaptability of the wind environment are analyzed.The spatial pattern of chongqing commercial center is rooted in the expansion of land use in the main urban area,which forms a "multi-center and group-type" spatial structure due to the limitation of land use,and the production factors of each urban group gather to form their own commercial center.The commercial center has the characteristics of high height,high intensity,obvious mountain features and insufficient open space,and also shows the characteristics of inadequate adaptability of wind environment.Then,from the three levels of block texture,street form,architectural form and combined layout,the paper analyzes the relationship between the spatial elements on the micro scale of the commercial center and the wind environment.Then,on the basis of correlation analysis strategy is put forward,from block texture,street layout three aspects of form,construction form and composition,based on the wind environment of the central business district of space optimization strategy:block texture optimization strategy,including the basic land index,mountain block breeze,mountain block of three-dimensional wind and sky open degree,high partitionelements such as optimization;The optimization strategy of street form includes the optimization of basic street form index,mountain street permeability,street interface continuity and building tiling rate,etc.The optimization strategy of architectural form and combination layout includes the optimization of architectural complex spatial layout form,single building windward face form,high-rise and slab building form,high-rise podium building form,overhead area of the bottom floor and other elements.Finally,the spatial optimization strategy of the above mentioned business center is extended to an empirical case to verify whether it can optimize the wind environment of the case.Taking the three gorges square as an empirical case,wind speed and PM2.5were included as the analysis variables of the wind environment,and the characteristics of the wind environment were quantitatively analyzed by field measurement and CFD simulation.The experimental results showed that the three gorges square had a poor wind environment,high static wind rate,and excessively low wind speed,which could not effectively diffuse particles.Then,in view of each measuring point for the analysis of the three gorges square wind environment and its spatial correlation,on this basis,from the block mechanism,streets,morphology,architecture form and the combination of three aspects put forward aiming at the three gorges square layout strategy and optimization scheme,and comparative analysis of three levels: form parameter,and using the CFD simulation of the quantitative analysis of the wind environment changes:the optimized calm wind rate from 64.13% to 59.8%,wind speed generally improved,the site of 24 and points out that the space optimization strategy based on the wind environment has certain extension.However,in view of the economic and property rights problems,it is impossible to optimize the space of the completed three gorges square on a large scale.The empirical part of the paper adopts field monitoring and computer simulation technology,and the research method conforms to the development trend of urban planning towards science.However,the depth of this paper needs to be explored.There are still some deficiencies in the studies on the limitations of strategy application,incomplete wind environment evaluation index system,weight coefficient of morphological parameters,etc.,which are expected to be strengthened in the follow-up studies.