Phase II Beijing Metro extension complete 18 Mar 2014
Desiree Willis, Technical Writer, The Robbins Company
- Breakthrough on the last section of Beijing Metro Line 6 Phase II marks completion of a 12km extension in the Chinese capital.
- A Robbins 6.15m diameter EPBM excavated the final 2.3km of alignment in just three months for contractor China Railway Engineering Corporation (CREC) Bureau 5. Geology was a mix of soft soils, clay, sand, pebbles, and highly weathered rock.
- With this breakthrough, achieved earlier this year, the Robbins EPBM contributed to the 12km of existing 30km tunnel that will allow seven new stations to open in September 2014. A second western extension, planned in 2015, will make the entire route 54km in length.
- "The Robbins machine proved good and reliable," said Wan Ming, Mechanical Electrical Manager for CREC Bureau 5. Efficient excavation led to advance rates of 125m/week and 410m/month which was achieved through a mixture of consistent ground conditions, field service support, and custom EPB design. This included a spoke-type cutterhead and shaft-type screw conveyor, as well as active articulation to negotiate curves down to a 1,000m radius. Support is provided via 1.2m long universal concrete segment rings.
A total of 887 rings line the tunnel
- Tunneling in urban conditions made achieving high advance rates challenging: structures along the tunnel route included high voltage lines within 1.5m of the excavation, a 30m wide river, a 200m long machine factory, and a variety of active utility pipes.
- "The ground condition in Beijing is loose, soft ground with fine sand. We reduced the torque by injecting Bentonite into the cutterhead. We were also able to maintain a good rate of advance with high-powered VFD electric motors (5 x 800 kW) and with the help of a good crew for trouble shooting," said Andrew Han, Robbins Field Service Manager. "We are proud that we overcame challenges through joint efforts by Robbins and the customer CREC Bureau 5. This is the first time that an EPB on this project has excavated a tunnel so quickly, breaking through in three months," said Han.
- As part of ongoing efforts to alleviate traffic pressure, more extensions to Beijing's 16 active metro lines are expected. The overtaxed system currently carries 10 million passengers daily, and will be able to increase capacity by 700,000 upon completion of Line 6, according to the municipal transport commission. Once all three phases of Line 6 are complete in December 2015, the extension will run parallel to Beijing's oldest subway, Line 1, opened in 1971, and will serve as a relief to the aged and overcrowded route.
- The breakthrough marks the completion of the last section of the Line 6 Phase II extension, further lengthening Beijing Metro's longest subway route. With a population of nearly 20 million people, the extension was essential in sustaining rapidly growing transportation needs, resulting in a higher capacity metro system.
Swift EPBM makes its mark in Zhengzhou - TunnelTalk, April 2011
Robbins EPBMs undercut downtown Zhengzhou - TunnelTalk, October 2010
Robbins consolidates presence in China - TunnelTalk, March 2011
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