Study On The Evolution Of Underground Public Space In Japan From The Perspective Of Three-dimensional City

Due to the limited land resources and the contradiction between man and land,cities in Japan have developed in a three-dimensional way in order to solve this problem and underground public space is an important part of three-dimensional cities.Since the first subway was built in 1927 in Tokyo,the development and utilization of underground public space in Japan have been at the forefront of the world after nearly a hundred years of development.From the perspective of a three-dimensional city,this paper analyzes the evolution of underground public space in Japan by using literature research,field research,and interdisciplinary research methods.In this study,the evolution process is divided into "current situation","development stage" and "evolution trend" according to the time dimension.First of all,through the literature review and the theoretical construction of the "three-dimensional city",the principles guiding the field research are obtained and 7targeted cities and more than 40 underground streets are selected as field research objects.Then,the status report of underground public space in three-dimensional cities in Japan is presented.After understanding its present situation,based on the relationship between the underground public space and the three-dimensional city,the development of underground public space in Japan is divided into four stages,which are "the initial stage as the function of the three-dimensional city","the expansion as the extension of the threedimensional city","stagnation stage as a potential safety hazard of the three-dimensional city" and "reconstruction stage as public attribute of the three-dimensional city".Furthermore,this study summarizes the evolution mechanism and analyzes three typical development trends of the underground public space in Japan through 6 cases of threedimensional urban areas,which are the trend of spatial intensification,the trend of spatial composition,and the trend of spatial composition.Finally,reviewing the present status and the evolution of underground public space in Japan,this paper summarizes its existing problems,challenges,and future development opportunities.At last,based on the study of underground public space in Jpan,the enlightenment of the development of underground public space in China is put forward.