Robbins EPBM to China's new Chengdu Metro
Robbins EPBM to China's new Chengdu Metro Oct 2009
Chengdu, one of China's principal cities with 11 million inhabitants, will soon have a reduced commute time thanks to an extensive new metro system. Five lines totaling 126km (78 miles) will be constructed using several TBMs. Robbins signed a contract with China Railway Construction Corp, (CRCC) in January 2009 for a 6.26m (20.5ft) diameter EPBM and back-up system for Line 2, Lot 18 of the new metro system. A commissioning ceremony was held in Chengdu on October 14, 2009.
Pic 1

TBM commissioning ceremony

Geology will include a matrix of weathered rocks found nowhere else in China, consisting of highly permeable pebbles, sand, and clay. Subsidence will be intensively monitored with crews using probe drilling and ground consolidation if settlement is detected.
A mixed ground cutterhead, dressed with 17in diameter disc cutters and carbide bits, will be utilized to effectively excavate the variable geology. Cobbles averaging from 20mm to 80mm in diameter are predicted, with diameters of as large as 120mm (4.7in) possible. Muck will be removed using an 800mm (31in) diameter shaft-type screw conveyor and battery-operated rolling stock.
Assembly of the TBM was completed in a manufacturing facility in Chengdu. The machine is due for an Autumn 2009 launch and will bore two 1.35km long sections in a suburban area of the city. The tunnel alignment takes the machine 25m (82ft) beneath residential buildings, and through several curves with a minimum 400m (1,300ft) radius. Active articulation will be used to prevent ring deformation in curved portions of the tunnel.
The Chengdu Metro will open in three stages. The 26.7km long Line 1, providing service between Honghuayan and Shiji Square stations, will open in 2010. The 50.6km long Line 2, for Chengdu Metro LLC and with 17.6km of the alignment underground, will include 26 stations between the Longquandong and Shiniu areas. Seven lines totaling 274km (170 miles) are planned to be in service by 2035 to serve an estimated 13.1 million passengers rides daily.


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