SEVEN EPBMS AT WORK ON THE SHANGHAI METRO

This article describes tunnelling and station building now in progress for the construction of Shanghai Metro Line 2; it includes a route map. Seven earth pressure balance machines (EPBMs) are now being used to drill the Line 2 running tunnels; they had completed 8.2km of tunnels by early November 1997. Three additional EPBMs will be in use in 1998. Stations are being built at the same time, using cut-and-cover. The ground is a succession of clay layers, with man-made fill on top, and a hard green clay bed at the bottom. The water table is from 0.5m to 1.0m below the surface. At Shi Men Station, a 268m long by approximately 20m wide by 11.1m deep station box is being constructed; it will accommodate two levels and three spans under 2.5m of overburden. It has rectangular reinforced concrete support columns, two ventilation shafts, and four access tunnels. It was difficult to construct such a large bentonite slurry diaphragmed wall box at that site, and compensation grouting was used. The largest station, at People's Plaza, caters for a future metro junction, and one end of it is very near Line 1. It will have three decks, with the trains on the bottom deck, ticket halls and passenger area and cycle storage on the middle deck, and commercial property on the top deck. Its box is 372m long, up to 40m wide, and up to 23m deep.