ABSTRACT
Shanghai is the largest financial centre in China with a population of about 23 millions. In order to alleviate the increasingly severe congestion problems in this city, underground metro network has been developed in stages in Shanghai. Since the first metro line (Line 1) was started in operation in 1995, there are 11 metro lines (excluding the Shanghai Maglev airport link) and 267 stations built. All tunnels of these 11 metro lines were driven using an Earth Pressure Balance (EPB) machine. The external diameter (D) of tunnel is typically 6.2 m and is located at relatively shallow depths (about 13 m below ground) in soft clay. The total length of tunnels in operation is 410 km in 2010 (see Fig. 1), making the Shanghai metro network the longest in the world. It is anticipated that a total of 510 km long of track will be in operation by 2012 and further increased to 877 km long by 2020.
