Eight tunnel boring machines from Herrenknecht excavated almost 16 km of tunnel in only 20 months, crossing beneath the emerging metropolis of Wuxi. The machines mastered challenging stretches with small overburdens. The last breakthrough, for the time being, was celebrated on March 3, 2013. The first two metro lines in the 3,000-year-old town on Taihu Lake near Shanghai are expected to start operation in 2014. A total of 5 metro lines are planned.
A total of 8 earth pressure balance TBMS from Herrenknecht, each approximately 6.4 m OD, have tunneled through the underground since July 2011 to construct the first two metro lines in the metropolis of Wuxi in eastern China. For the construction of Wuxi’s first two metro lines, they excavated a total of almost 16 km.
On March 3, the TBMs completed their mission with the final breakthrough of the S-730 tunnel boring machine. With top performances of more than 33 m/day and 164 m/ 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 EPB 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 more than 4 million inhabitants, is situated in the east of China near Shanghai and 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. 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. Around 100 further kilometers are currently under construction.
Wuxi Metro Line 1 and Line 2
Machine data Project data
Machine type: 8 x EPB Shields Tunnel length, total: 15.66 km
Diameter: 6,370 – 6,390mm Geology: Wuxi Clay
Installed power: 600 – 675kW
Client: Wuxi Metro Group Co., Ltd
Customers: Shanghai Mechanized Construction Co. Ltd.; Shanghai Baoye Construction; China Railway
14th Bureau Group Co. Ltd.; China Railway 19th Bureau Group Co. Ltd.; China Railway 1st
Group Co. Ltd. (CREC); Wuxi HongYuan Construction Group Co. Ltd., China Railway
Tunnel Group 3 Bureau