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基于人类尺度营建的古城道路网经过历史演化具有分形结构。在汽车成为道路设计导向的背景下,立足于分形连接的古城道路网应回归人性化出行的视角,应用Hausdorff维数简化分析法、长度—半径维数分析法及分枝数目—半径维数分析法,对1735年、1893年、1949年及2014年四个时期西安古城道路网进行了分形维数的测算,揭示了道路网分形演化趋势和不同时期的分形特征,探讨了演化原因并确定了分形演化过程中的三个阶段(不断向更高层次演化阶段;演化到较高等级,但外部因素对道路网产生逆向扰动;处于较高层级,但交通方式变革使基于人类尺度的道路网在结构和功能上发生局部蜕变),指出目前西安古城道路网在结构和功能上的局部蜕化趋势不容忽视,并针对问题提出应推崇适宜步行和自行车出行的模式典范,对古城道路网保护乃至整个古城的可持续发展具有重要意义。
The ancient city road network constructed on the basis of human scale has a fractal structure through historical evolution. In the context of the automobile as the road design guide, based on fractal connection of the ancient city road network should return to the perspective of human travel, the application of Hausdorff dimension simplification analysis, length - radius dimension analysis and branch number - radius dimension analysis Method was used to calculate the fractal dimension of Xi’an ancient city road network during the four periods of 1735, 1893, 1949 and 2014. The fractal evolution trend of the road network and fractal features at different periods were revealed. The three stages in the evolutionary process of fractal evolution (evolving to a higher level of evolution; evolving to a higher level, but external factors have adversely perturbed the road network; at a higher level, but changes in the mode of transport have made road networks based on human dimensions Structure and function of the local transformation), pointed out that the current Xi’an city road network in the structure and function of the local degeneration trend can not be ignored, and proposed for the issue should be suitable for walking and cycling mode model, the ancient city of road network protection and the entire ancient city The sustainable development is of great significance.