Study on the Expansion System of Urban Space within City Circle——With the Central City within Nanjing City Circle as an Example

The influential factors of the expansion of city space within the city circle include natural limitation,human direction, traffic inducement,andeconomic direction.These factors interact on each other,forming a mode of vector,overcast and conformity.Nanjing,the central city of the Nanjing citycircle,has found a comprehensive method for analysis of its spatial expansion:to set up a reasonable comprehensive index system.Study by thismethod has come to the conclusion that Nanjing should develop eastwards and southwards.[