| China is in the stage of rapid development of urbanization and industrialization,so the urban spatial structure is also constantly changing.Since the concept of polycentric urban space development has been proposed by Western scholars,a large number of scholars in China have begun a large number of theoretical and empirical research,and many large cities have begun to show the development direction of polycentric spatial structure.The polycentric structure of the city can play a certain role in issues such as population evacuation,traffic congestion,and environmental degradation.The polycentric structure includes polycentric based on morphology and polycentric based on functional connection.Domestic scholars have rich research on morphological polycentric,while functional polycentric needs further research,and the essence of “polycentric” is not only to make the city To achieve polycentric in the spatial form,it is more necessary to maintain the strength of the association between the centers of the city.At the same time,with the wide application of network big data such as POI data,population heat map,network check-in data,etc.,it provides a new perspective for urban research,making the research results more accurate.On the other hand,the formation process of urban multi-center structure is complex,and the evolution mechanism of the formation process requires further exploration.Based on the above background,combined with the existing theoretical and empirical research.This paper takes the main urban area of Chongqing as the research object,and uses multi-source big data,including urban building 3D model data,Easygo Heat map,urban POI data,using cluster analysis,Spatial statistical analysis and other methods to identify the polycentric structure of urban form from different angles.At the same time,use the commuter flow data to identify the polycentric structure of the centers/groups in central city based on functional connections.Finally from landscape and urban planning,land use,and social economy Conditions and other aspects explore the evolution mechanism of the polycentric spatial pattern in Chongqing.The specific research conclusions are as follows:(1)The central Chongqing presents a typical "polycentric urban with multiple subcenters and urban clusters" in the morphological structure.The “one master and four deputy” in the main urban area include Jiefangbei,Guanyinqiao,Nanping,Shapingba,Dayangshi(Daping,Shiqiaopu,Yangjiaping)have better development,and the urban spatial factors are more concentrated,the spatial structure is relatively tightly distributed.The concentration of peripheral sub-centers(Xiyong,Chayuan)and group space elements are relatively weak,and there is a certain gap between the development of several central centers.According to different functional types POI analysis,the residential space,employment space and entertainment space in central Chongqing.But there are certain differences in the spatial agglomeration intensity.In general,the polycentric spatial structure of Chongqing has the characteristics of dense and sparse spatial structure and high level of development within the degree of development.The polycentric system needs further balanced development.(2)Based on the polycentric identification of the commute flow function.It was found that Chongqing has a polycentric in the functional sense.The function polycentric has obvious layer-type features in space.The inner center function of the inner ring is stronger than the center outside the inner ring.The connection strength shows that the contact between the two mountains(Zhongliang Mountain and Tongluo Mountain)is stronger than the two.At the same time,there are centripetal features in the direction of polycentric contact,that is,the peripheral center/group commuter flow is more to the central area,and is highly dependent on the five centers.There are also different characteristics in the commutation of the centers/groups inside and outside the group.The functional relationship between the core area and the northern group is stronger;the functional connection of each center/group node in the main city presents a core-edge spatial structure with geographical characteristics of distance attenuation.(3)The polycentric system in Chongqing is a system with both morphological and functional features.It has strong matching and coupling,and has obvious hierarchical structure.Due to the influence of landscape and urban planning,the morphological and functional synchronization of polycentric systems development.(4)The analysis of the evolutionary mechanism of the polycentric pattern in Chongqing shows that Chongqing’s unique geology as a mountainous city determines that the urban spatial structure of Chongqing will adopt a polycentric urban structure model.Polycentric is a passive choice under its natural constraints and ecological conservation;the polycentric spatial structure of Chongqing is the result of long-term efforts in several rounds of planning over the years.Over the years,urban planning has always been guided by the development model of urban spatial structure that guides its “one main,multiple,and multiple groups”.Land use planning and land market also affect the evolution process of Chongqing’s polycentric system.Land use structure and land market changes have a certain leading role in urban development;urban industrial structure adjustment,urban transportation infrastructure construction,population growth,etc.,indirectly promoted the formation of a polycentric system. |
