Study on the Evolution Characteristics of Spatial Structure in the Process of Expansion in Yangtze River Delta Urban Agglomeration

By analyzing the changes of city primacy, Gini coefficient, Herfindahl-Hirschman index and geographical connection rate, this paper explores the evolution characteristics of population spatial structure, and finds that in the process of capacity expansion, the population spatial structure of Yangtze River Delta urban agglomeration first develops in the direction of agglomeration, and then gradually evolves in the direction of polycentricity and decentralization. By constructing the spatial network structure of economic ties in the Yangtze River Delta urban agglomeration, this paper explores the evolution characteristics of spatial ties. The results show that: from the perspective of the overall network characteristics, in the process of the expansion of the Yangtze River Delta urban agglomeration, the number of network connections is increasing, but the network density is declining; from the perspective of centrality analysis, the core status of Shanghai and Hangzhou has declined, the core role of Nanjing and Hefei has become increasingly prominent, and the network has developed in the direction of multi centrality, forming a trend of continuous development of multiple metropolitan areas. From the perspective of multicenter characteristics analysis, the agglomeration characteristics are weakened, the dominant position of the first city is declining, and the polycentric characteristics are enhanced.