Marathon TBM finishes at Pinglu Dec 2010
Desiree Willis, Technical Writer, The Robbins Company
End of the line for single 25.4km long drive
- A veteran Robbins TBM has completed one of the world's longest single-drive TBM tunnels to date. At 25.4km (15.8 miles) long, the 4.8m (15.7ft) diameter machine bored the long drive to a successful breakthrough in November.
- The Pinglu Tunnel in northern China is the most recent leg of the country's Yellow River Water Diversion Project and was completed by the Sino-Austrian Hydraulic Engineering Co Ltd (SAHEC) JV, led by Alpine Bau GmbH.
- More than 500 people gathered at the breakthrough ceremony in a remote area of Shanxi Province to mark the occasion. "The key to this project's success was the crew.
- We had the right mix of experienced people and young people hungry to learn," said Paul Bargmann, Head of the Machinery Department for Alpine Bau GmbH. The Robbins machine successfully mined through difficult geology including coal seams and abrasive sandstone with up to 70% quartzite content. Advance rates topped out at 50 ring sets, or about 70m (230ft), per day.
Breakthrough celebrations in remote Shanxi Province
- The machine was previously used on a record-breaking 12km (7 mile) long segment of the Yellow River Diversion in 2000. On that project, the TBM set two world records in its size class of 4-5m (13-16ft) diameter: Best month of 1,855m (6,085ft) and best monthly average of 1,352m (4,435ft). Both records still stand.
- With the TBM designed already for similar geology, the the back-up was modified for the Pinglu Tunnel. "The back-up frame was extended from one stroke to two strokes. This was a key change, especially for such a long tunnel," said Meik Müller, Technical Director for Alpine's Asia Division.
- The modification allowed the machine to maintain good advance rates despite transit times of up to 70 minutes for muck trains traveling from the machine to the tunnel entrance. The hexagonal segmental lining for the Pinglu Tunnel was produced near the jobsite by Alpine. A crew of nearly 400 people worked at the remote segment factory.
- During tunneling, the segments were placed in rings of four elements, in a honeycomb configuration staggered longitudinally.
Rates of up to 70m/day were achieved
- The design was created to allow for high-speed, continuous boring with no downtime while erecting segments.
- The completed Pinglu Tunnel will go into operation in October 2011, connecting to the North Main Line of the Yellow River Project to transfer water to the Pinglu, Shuozhou, and Datong areas. The more than 100km (62 miles) of the South Main Line tunnel was excavated by five TBMs, including four Robbins double shields, between 1999 and 2001. The entire scheme will transfer water from the Yellow River to dry regions of Shanxi Province, an area that receives just 400mm (16in) of rainfall per year on average.
Single TBM heading record on current Pinglu tunnel drive - TunnelTalk, Aug 2009
Record setting TBMs on Yellow River drives - TunnelTalk, Jan 2001
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