Fast and Safe Through Wuxi, China
Apr 18, 2013
Eight earth pressure balance shields (Ĝ 6,370 to 6,390 mm) from Herrenknecht have tunneled through the underground since July 2011 to construct the first two metro lines in the 4-million strong metropolis of Wuxi in the east of China. For the construction of Wuxi's first two metro lines, they excavated a total of almost 16 km.
On March 3, they completed their mission with the final breakthrough of the S-730 tunnel boring machine. With top performances of more than 33 m a day and 164 m a week, the TBM made its way through the ground excavating a diameter of 6.39 m. Thus, 2,508 m of tunnel for metro line 2 were built in only 10 months.
Before that, the machines also mastered challenging tasks when constructing the metro tunnels for line 1. The S-663, a compact Earth Pressure Balance Shield with a diameter of 6.37 m, drove only a few meters beneath residential and commercial buildings. On Dec. 7, 2012, the machine achieved final breakthrough. Right at the start of tunneling, on May 24, only 7 m of soil were above the machine, and the distance to the foundation pillars of the building above were only 3.7 m. Therefore, the ground, consisting of strongly aquiferous clay, was treated with a special frost procedure. Following a smooth start, the machine quickly crossed beneath the building.
Wuxi with its more than 4 million inhabitants, situated in the east of China near Shanghai, is investing a great deal in the construction and extension of efficient public transport systems. At least 5 metro lines are to cross the city in future. The two metro lines 1 and 2 with a total length of 58.5 km are expected to start operation by the end of 2014. Line 1 will cross the city from north to south, and line 2 from east to west. Herrenknecht received orders for five EPB Shields for the construction of line 1, and orders for three machines were placed for the construction of line 2. The machines were assembled by the local branch Herrenknecht (Wuxi) Tunnelling Equipment Co., Ltd.
China's economic growth and the increasing urbanization have led to a high demand for efficient underground traffic and supply infrastructures. Chinese tunnel engineers have completed a total of 400 km of metro tunnels safely and quickly using Herrenknecht technology since the first project in Beijing in 2000. An additional 100 km are currently under construction.
This article was supplied by Herrenknecht AG.