Process, Characteristics and Influence Factors of the Huainan City's Spatial Expansion from The Embryology Perspective

Taking the Huainan City as a case, the article, combined all previous status information of the urban planning land and industrial development data, using the GIS technology platform, has researched the urban spatial form of Huainan City with the method of comparative study of superposition in different inspection points, measures the compact degree index, expansion speed and expansion intensity index of the urban spatial expansion form in different periods, and inspects the evolution process and features of the urban spatial form in Huainan City from the aspects of time and space. The result indicates that the urban spatial extension of Huainan City, as a coal city, demonstrates significant spatial orientation and structure characteristics of layers, with 7 stages including scatter development, node cluster expansion, enclaves expanding, axial extension, interior filling, integration and optimization, and location reengineering. In the process of spatial expansion, under the control of the coal resource, the drive of the coal industry and the expansion of the coal enterprise, the development of urban space experiences a changing process from compact to decentralized form and then back again under the influence of gradual filling and optimization adjustment. In different periods, West, North, East, South of the city became the main directions of urban spatial expansion in turn. From the macro level, the urban spatial structure, which has free space, presents binary spatial structure— urban-industrial areas. Instead, it is the dissimilated band structure. Along the main traffic arteries, there are residential areas, commercial areas, office area on both sides and the factory sector outward side. From the micro level, residential areas are around the coal enterprise center layout. The urban spatial structure presents ternary structure, including management area, office-residential area and coal mining area. In addition, the expanded speed and strength of urban spatial is greater different in different historical periods. Before the mid 1980s, it expanded slowly. From the mid 1980s to the mid 1990s, it kept medium speed. Since the mid 1990s, it expanded rapidly. And the urban spatial expansion of three main directions(North, West, and South) is faster than the East. The analysis concludes that, the dominant factors of urban spatial expansion are different at different stages of evolution of Huainan City. At the formative period, resource and the occurrence of the city commuting are the dominant factors led the urban spatial form change. At the growing period, the long-term national energy strategies and transportation drives the growth of the city. At the mature period, the industrial structure succession is the dominant factor. At the transition period, it is led by the interaction of the space economy and planning regulation.