中文摘要：

日益受关注的城市群是国家参与全球竞争与国际分工的地域单元。在定义城市群的基础上,提出了城市群多层次空间结构分析算法。该方法在评价城市综合实力的基础上确定核心城市,依据核心城市的通勤圈确定研究区域;在计算城市间多模式交通可达性的基础上评价城市间相互作用强度;利用城市综合实力指数及相互作用强度进行城市群多层次空间结构分析,从复杂的城市群相互作用网络中分析确定其等级结构体系——多层次空间结构树。以京津冀城市群为例进行了实证分析,给出了城市群边界和空间结构。研究认为北京城区周边缺乏成熟的二级中心城市,而在天津地区,天津市城区具有较强综合实力,形成相应的辐射圈,与天津滨海新区形成双核结构。最后对模型的应用进行了讨论。研究表明：提出的模型架构为利用计算机的大数据快速处理能力进行城市群复杂网络分析提供了有益探索,将为城市群空间决策提供良好的支撑。

英文摘要：

Urban agglomeration plays a key role for China in attending the global divisions of labor, international competitions, as well as the integration of regional economy. Various scholars have dedicated to the study of urban agglomeration. However there is no consensus on the definition of urban agglomeration, which leads to the controversy. Relations between each city- pair in an urban agglomeration may form a complex network which brings a great challenge for researchers to use traditional method to synthetically analyze the spatial structure,due to the exponential calculation time increased by a great number of nodes. Based on the summary of different definitions, a novel method is developed to analyze the multi-level spatial structure of an urban agglomeration. We first find the core cities by calculating the urban centrality of each city in an urban agglomeration using several selected indices. To be specific,the spatial scope of the urban agglomeration can be defined as the 2- hour commute range of each core city. Then interaction intensities between each pair of cities are calculated based on the traffic accessibility and cities＇ scale. We develop an algorithm to analyze the spatial structure based on the so- called Multi- level Spatial Structure Tree（MSS- Tree）, which can be used to analyze the urban agglomeration structure in detail. Finally, we carry out the sample study of Beijing- Tianjin- Hebei urban agglomeration to testify the model. The experimental results show that due to the centrality of Beijing downtown area, cities or towns around Beijing have much more interactions with Beijing than among themselves. It could be concluded that mature sub-center cities or towns around Beijing are needed to take the responsibility of service provision. In comparison, Tianjin downtown area and Tianjin coastal district have double cores in Tianjin. Hengshui city far away from Beijing downtown area has the potential to become a secondary central city in the near future. The case study also demonstrates that th