| As one of the cradles of the Chinese nation, Xi'an is a most famous historical city in the world. With a capital history of twelve dynasties, it is one of the six most ancient capitals in China. The accumulation of long history and culture forms the deep texture in Xi'an city's > spatial structure evolution.This essay takes Xi'an city's space-time array as the main thread and comprehensively analyzes the evolution and change of Xi'an city's spatial structure since Xizhou Dynasty. The author briefly discusses the urban spatial structure form, layout character and the evolution mechanism during the period when Xi'an is the capital of the united nations in Chinese history, so as to explore the motive power mechanism and the deep structure under Xi'an city's spatial structure's evolution.The essay pays more attention to the evolution process of Xi'an city's spatial structure's evolution since the foundation of P.R.C.. The relationship between urban planning and urban spatial structure's evolution is discussed. The author insists that urban planning possess the guide function to urban spatial structure's expansion and evolution; state policy and social politics are decisive to urban spatial structure's expansion; industry arrangement, economic development and Development Zone's construction are motive powers to Xi'an urban spatial structure's evolution.The author, from different perspectives, studies Xi'an urban spatial structure's components and their evolution characters. Then the restricted factors inflecting Xi'an urban spatial structure's expansion are analyzed. The author also studies dominant and relevant factors influencing Xi'an urban spatial structure's expansion. After the research of the expanding direction and leading factors of Xi'an spatial structure, the author insists that urban spatial expansion has the character of diversity.In the essay, fractional method is used to determine the spatial form of a certain site in the downtown of Xi'an city. The author analyzes urban spatial form's random quality and rise and fall phenomenon, and then calculates its fractional dimension value.The author also studies the evolution mechanisms exist in Xi'an urban spatial structure's evolution which are self-organization and organization mechanism, agglomeration and diffusion mechanism, ecological mechanism. The author raises the developing trends of the future urban spatial structure, which are sustainable, ecological, informational, regional and openness, at the same time, the historical relic and urban texture's protection will be emphasized. The author suggests Xi'an urban spatial structure in the future should be based on the whole region around. Only in this way, can the too dense urban function be organically decentralized. To attain this goal , the adjustment of the administrative area of Xi'an must be solved. The author insists that the multi-core spatial structure can free the city from the dilemma of development and protection and available to the whole region's development. |
