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TBM RECORDER Slurry TBM ends Zhanjiang Bay underpass 27 Feb 2013
Desiree Willis, Technical Writer, The Robbins Company
After advancing at up to 392m/month, a Robbins slurry TBM made a photo finish breakthrough to complete a 6.26m diameter pipeline tunnel under Zhanjiang Bay in China's southernmost city. The subsea tunnel runs 56m below water level, and will provide fresh water to the Guangdong steel plant via twin pipelines. Breakthrough of the tunnel drive at the end of 2012 prepares the project to come online in March 2013.
  • Undersea drive breakthrough

    Undersea drive breakthrough

  • Robbins Project Manager David Han inspects the slurry machine

    Robbins Project Manager David Han inspects the slurry machine

The 2.7km long conduit, constructed by contractor Guangdong No. 2 Hydropower Engineering Co, was completed by a Robbins slurry machine working at up to 6 bars operating pressures under the bay. The machine, supplied and assembled by Robbins with key components and engineering from Mitsubishi Heavy Industries Mechatronics Systems (MHI-MS), was launched in September 2011.
"The cutterhead design, layout of the cutters and injection ports were the most important design factors in completing this tunnel project," said Qinghua Shi, Chief Project Engineer for the contractor.
The high-powered Robbins machine featured a smooth flow cutterhead to allow for easier removal of stones and boulders while avoiding clogging at the face. The mixed ground machine was dressed with interchangeable knife-edge bits and disc cutters ready to work through geological conditions that included abrasive sand, gravel, and silt. The 'smooth flow' design approach for mixed face conditions is consistent with the Robbins design for mixed face EPB-type machines.

A cutterhead designed for mixed face conditions and smooth flow excavation to complete the 6.26m o.d. Zhanjiang Bay subsea water pipeline tunnel

During excavation, the Robbins TBM advanced at up to 27m/day with no interventions needed. "Throughout the project, there were no significant problems that happened," said Shi. "I am happy we could operate the machine properly. The launch and breakthrough went very smoothly and no cutters needed changing even though this was a long tunnel excavation."
Once in operation, the Zhanjiang Bay subsea tunnel will source water from the nearby Jianjiang River to the steel plant on Dong Hai Island. The water supply for the large company of 20,000 employees is part of a plan by the Chinese government to improve the quality and output of steel in Guangdong Province.
References
First Robbins slurry TBM set for launch - TunnelTalk, August 2011
Robbins consolidates presence in China - TunnelTalk, March 2011

           

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