First Robbins slurry TBM set for launchAug 2011
Desiree Willis, Technical Writer, The Robbins Company
Robbins is to launch its first ever slurry TBM under the waters of China's Zhanjiang Bay.
At an acceptance ceremony in Shanghai in June contractor Guangdong No 2 Hydropower Engineering took delivery of the 6.26m (20.5ft) TBM which marks Robbins' first venture into the slurry TBM market.
The machine will be shipped to the jobsite and lowered down a 28m (92ft) deep shaft to excavate the 2.7km Zhanjiang Bay Cross-Sea Tunnel. The tunnel, with up to 60m (200ft) 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.
The 6.26m diameter Robbins slurry TBM accepted for the sub-sea Zhanjiang Bay drive
The high-powered Robbins machine features 20 thrust cylinders for a total thrust of 46,000kN, a feature needed due to the 6 bar of hydrostatic water pressure expected at tunnel level under the bay. The geology comprises coarse abrasive sand, gravel and silt. A mixed ground cutterhead with hard facing will be dressed with interchangeable knife-edge bits that can be switched out for disc cutters.
An abbreviated back-up system will be used during launch owing 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 Mitsubishi Heavy Industries of Japan, and assembled by us with some Robbins components," said David Han, Project Manager for Robbins. "It is our entry into the slurry market, the first machine of this type manufactured by Robbins," he added. MHI-MS Ltd 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.
Once complete, twin pipelines will be fitted into the subaqueous segmentally-lined tunnel to provide fresh water to the Baosteel Plant, a large steelworks 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.
Thank you for taking the time to share your thoughts and comments. You share in the wider tunnelling community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language professional.
Your feedback has been submitted successfully and is currently under review.