Study On The Evolutionary Characteristics And Dynamic Mechanism Of Spatial Pattern Of Chinese Urban Agglomerations Under The Background Of High-speed Railway Network

The urban agglomerations relying on the developed infrastructure networks such as transportation and communication,as an important carrier of the national regional spatial development strategy,play a growth pole role in regional economic development due to scale effect,agglomeration effect,radiation effect and linkage effect.High-speed railway(HSR),which is an important symbol of modern railway high-tech,can greatly reduce travel time between the two cities,accelerate the flow and integration of people,materials,capital,technology,information and other elements,and ultimately have a profound impact on the regional economic efficiency,the spatial distribution of economic activities and urban spatial pattern.In recent years,as an important growth engine of China,high-speed railway has developed extremely rapidly,and China is stepping into the era of high-speed railway in an all-round way.The evolutionary characteristics and dynamic mechanism of the spatial pattern of China’s urban agglomerations may change significantly due to the increase of opening time and mileage of high-speed railway lines and the increasingly improved high-speed railway network.Under the background of high-speed rail networking,it is of great theoretical and practical significance to explore the spatial pattern evolution of urban agglomerations in China for the implementation of national regional coordinated development strategy.Based on this,this paper studies the evolution characteristics and dynamic mechanism of urban agglomeration spatial pattern in China under the background of high-speed rail networking,and conducts empirical tests.First of all,this paper combs and interprets the related theories of spatial pattern evolution of urban agglomerations,and reviews the literature related to both high-speed rail and the evolution of urban agglomerations spatial patterns,and finds the theoretical basis that high-speed rail influence on the spatial pattern evolution of urban agglomerations on the “point-line-surface” dimension.Secondly,taking the six major urban agglomerations of China as the research object,this paper descriptively analyzes the general situation of urban agglomerations and the status quo of its high-speed railway development,collects the 2018 railway train schedules,railway passenger trains data and macro data of 2002-2016,such as economy,population factor.According to that,it analyzes the characteristics of high-speed rail network of six major urban agglomerations and describes the spatial pattern evolutioncharacteristics of six urban clusters under the background of high-speed rail networking.In addition,we summarize the correlation between high-speed rail networking and urban agglomeration spatial pattern evolution.Then,based on the framework of new economic geography,the dynamic theory of spatial distribution of economic activities is summarized on the theoretical level,the agglomeration and diffusion mechanism that high-speed rail affect the spatial pattern evolution of urban agglomeration is elaborated concretely.Furthermore,a two-region equilibrium model is constructed,and the process of this dynamic mechanism is analyzed through numerical simulation.Finally,we construct a multi-period difference in difference(DID)model and threshold panel model,using the high-speed rail opening data and economic,population and other macro data of the prefecture-level cities in China’s six major urban agglomerations from 2002 to 2016,respectively,to examine the agglomeration and diffusion effect of urban economy and population which are caused by the opening of high speed rail.And heterogeneity tests were carried out on cities with different scales and different economic levels.The study found that the construction of high-speed rail networks in the six major urban agglomerations has significantly improved the average accessibility within each urban agglomeration,and connectivity and linkage strength of high-speed rail between the node cities has enhanced.Under the background of high-speed rail networking,the single-center and multi-center distribution of the spatial pattern of economic and population factors of the six major urban agglomerations remained generally stable,but its single-center degree showed some fluctuations.Meanwhile,under the high-speed rail network,the urban spatial linkages within the six major urban agglomerations have been strengthened,and the spatial distribution of urban economic and population in the six major urban agglomerations has a certain coupling with the distribution of high-speed rail network.In the numerical simulation,with the decrease of transportation cost caused by high-speed rail,the agglomeration trend of urban is enhanced in the short term,but the agglomeration intensity of urban tends to increase first and then weaken in the long term.From the perspective of the urban agglomeration as a whole,the opening of the high-speed railway has significantly promoted the urban economic agglomeration and caused the diffusion effect of the urban population,and has obvious time accumulation effect on the urban economic agglomeration.Moreover,for each urban agglomeration,cities with different scales and different economic levels within urbanagglomeration,high speed rail has different influence intensity and significance on urban economy and population.