Study On The Spatial Structure Characteristics And Expansion Mechanism Of The "Circle Core" In Nanjing Metropolitan Area

Metropolitan area is a regional spatial form,which is closely related to the central urban area and peripheral area in the process of urban regionalization.It is a highly urbanized area in the city',a high level industrial agglomeration area,a embodiment of the core competitiveness of a city,and a lot of cities to seek higher regional status and participate in regional competition.A form.With its growth,the spatial structure of urban areas is also in the process of continuous development and evolution.In order to prevent the disorderly spread of the central urban area,optimize the spatial structure of the metropolitan area and improve the spatial use intensity of the urban area,the multi center structure is the space strategic choice of most metropolitan areas.However,the development stages and conditions of each city are different.In the process of development,different factors play a role in the development process,and the multi center space structure also has different forms of expression.For the study of Nanjing metropolitan area,it is found that the spatial structure at the present stage is a spatial form distributed at all levels according to hierarchical distribution.To summarize the characteristics and laws of this space structure is a kind of exploratory research on the development of space in the specific period of the development of the metropolitan area.The analysis of its development and evolution mechanism is beneficial to the more scientific guidance of the development of the future development strategy of the metropolitan area.This paper takes Nanjing metropolitan area as an empirical case,combs the course of its development,divides three stages of development according to the characteristics of space expansion,and dynamically displays the process of spatial evolution in Nanjing metropolitan area.In the analysis of the status quo space,refining and simplification,the spatial form is summarized as the "circle core" spatial structure.Under this structure,Nanjing metropolitan area has a hierarchical and circle layout pattern,with the center of the city as the center,the main city,the Vice City,the new town,etc.,in the main core layer(0-10km),the subcore layer(10-20km)and the auxiliary layer(20-30krn),using the ring fast.The road and the ecological green space are segmented,and the center and periphery of the urban area are conveniently linked through the radioactive trunk road and rail transit.In order to analyze the structure,the whole spatial structure is divided into different components,and the structure is depicted in detail from the public center system,road traffic system and ecological open space.On this basis,it is concluded that there are some restrictive problems in Nanjing metropolitan area,such as the spread of the main city space,the weak decompression capacity of the main city and the clear focus of the space development.Through theoretical deduction,the paper thinks that the analysis of the evolution mechanism of space structure should not only pay attention to the influence of the change process of the right of the behavior subject in the social structure to the space,but also take into account the material space level of the urban planning.On this basis,the theoretical analysis framework based on "factor behavior space" is constructed,and the specific process of spatial evolution is analyzed from two aspects of element composition and behavior subject.Econonic factors,institutional elements,environmental factors and technical elements in the factor level produce four kinds of forces in the process of spatial evolution.The upper government,local government,market capital and social residents on the level of behavior subject are based on different behavior purposes,respectively.We should play a role in determining the macro development environment,leading the direction of space development,forming a development alliance with the government,and meeting the needs of individuals.The coupling of the two levels determines that the Nanjing metropolitan area is a "circle type" spatial structure pattern.On the basis of the above research,the article analyzes the advantages of the space structure and the possible problems in the future development,and puts forward the concrete action strategy of the future urban space development in the light of the actual situation of the development of the metropolitan area in Nanjing,and provides the basis and reference for the development strategy of the future metropolitan area.