中文摘要：

城市增长边界是近年来城市规划研究的热点，而识别和理解中心城区实体边界动态变化以及影响因素，有助于合理设定城市增长边界。以陕西关中地区中小城市中心城区空间扩展实体边界区域为研究对象，基于渭南、铜川、华阴、韩城和兴平中心城区的影像资料和实地调研信息，探寻其实体边界区域建设用地扩展、形态、产业布局、用地、人口和活力等特征，提出空间扩展的非完全圈层式多方式交替特征、用地构成变化与实体边界区域外围继续扩展与否有关、边界区域空间要素有着基因传承的演变特征等规律，并对城市实体边界动态推进的区位、推力和尺度进行了探讨。

英文摘要：

Identifying and understanding the spatial evolution of extended physical boundary areas of medium and small cities are valuable for delimiting the urban growth. This paper addresses the spatial element charac- ters such as land use, form, industrial layout, population density and vitality based on the image data and in- depth site visit of Weinan, Tongchuan, Huayin, Hancheng and Xingping cities, and reveal the regularity of spatial expansion model and land use. Furthermore, the paper explores the location, drive forces and dimen- sion of extended physical boundary areas.