Contractor, Guangdong No. 2 Hydropower Engineering Co., Ltd, will launch its 6.26m diameter Robbins Slurry TBM in mid-September 2011 on the 2.7km long Zhanjiang Bay Cross-Sea Tunnel in China. An acceptance ceremony for the TBM was held in Shanghai on June 28, 2011.
The Slurry TBM will be shipped to the jobsite and lowered down a 28m deep shaft. The tunnel, with up to 60m of overburden, is part of a larger fresh water transfer project that will draw from the nearby Jianjiang River to supply a new steel plant on Dong Hai Island. An abbreviated back-up system will be used during launch due to limited site space, allowing the machine to begin boring with umbilical cables connected to gantries at the surface.
“This machine has been designed by MHI-MS, and assembled by us with some Robbins components. It is our entry into the Slurry market– the first machine of this type manufactured by Robbins,” said David Han, Project Manager. Mitsubishi Heavy Industries Mechatronics Systems, Ltd. (MHI-MS) has provided key components and engineering for both the TBM and back-up, while Robbins, in addition to component supply and assembly, will provide local support throughout excavation.
The high-powered Robbins machine features 20 thrust cylinders for a total thrust of 46,000 kN (10.3 million lb)—a feature needed due to the 6 bar of water pressure expected in the bay. A mixed ground cutterhead with hard facing will be fitted with interchangeable knife-edge bits that can be switched out for disc cutters in geology including coarse, abrasive sand, gravel, and silt.
Once complete, twin pipelines will provide fresh water to the Baosteel Plant, a large company with 20,000 employees. The water supply project is part of a plan by the Chinese government to improve the quality and output of steel in Guangdong Province.