NKK Builds Shield Tunneling Machine For New Yokohama Subway
A large-diameter shield tunneling machine for use in subway construction, the first of its type, has been completed at NKK's Tsurumi Works. The high-performance mud-pressurized Developing Parallel Link Excavating (DPLEX) type machine with a 7,150mm outside diameter will be used to dig a 452-meter section of the Honcho Shield Tunnel for a new subway system that is being developed by Yokohama City as part of its Minato-Mirai 21 Line Project. The new MM21 subway line, extending for 4.1km from Yokohama Station to downtown Motomachi via the MM21 area, is scheduled to begin service in fiscal 2003. The Honcho shield tunnel work, being undertaken by a Hazama Corporation-led consortium, entails the digging of a 452.91-meter up-line tunnel from Kenchomae (provisional) Station using the NKK-supplied DPLEX shielding machine. After arriving at Kitanaka (provisional) Station, the machine will be turned around and used to dig a 431.81-meter down-line tunnel, thus completing two single-track subway tunnels. This is the first time that the DPLEX shield tunneling method is to be employed for railway tunneling. It offers many advantages, including electricity cost reductions and easy installation. The latest shield tunneling technology provides various options by accommodating circular, rectangular or horseshoe-shaped cutter frames. Use of the decentered multi-shaft machine greatly reduces cutter torque compared to conventional single-shaft machines, leading to savings in power consumption and enabling economical long-distance driving. The cutter bits fitted to the cutter frames to make parallel link motions via crankshafts are highly resistant to wear, impact shock and damage. The multi-shaft machine is also easy to dismantle. NKK has nearly 20 years experience in supplying a broad range of shield tunneling machines for use in sewage and railway construction projects in Japan and other Asian markets. The company intends to meet diversified user needs dealing with varied operational and soil conditions. |
