Robbins slurry TBM for sub-sea driveSep 2010
The Robbins Company News Release
The Robbins Company marks its entry into the slurry TBM market with supply of a 6.26m diameter machine for a 2.7km long water supply tunnel under Zhanjiang Bay in China.
The machine will be assembled in the Robbins Shanghai manufacturing facility and built as part of a full cooperation agreement with Mitsubishi Heavy Industries Mechatronics Systems, Ltd. (MHI-MS) of Japan. Robbins will supply components in China, manage assembly of the machine, and provide local support throughout excavation. MHI-MS will provide key components and engineering expertise for the slurry TBM and back-up system.
A 5.44m diameter Mitsubishi slurry machine supplied to a Tokyo Metro project (Copyright Mitsubishi Heavy Industries Mechatronics Systems, Ltd. 2010 All rights reserved)
The machine will be delivery in March 2011 to the contractor Guangdong No. 2 Hydropower Engineering Co., Ltd. to excavate the sub-sea tunnel beneath a cover of 22m to the seabed and under a hydrostatic water head of some 60m. The high-powered machine features 20 thrust cylinders for a total thrust of 46,000 kN-a feature needed to counteract the 6 bar water pressures anticipated at tunnel horizon. A mixed ground cutterhead with hard facing will be fitted with interchangeable knife-edge bits and disc cutters for geology comprises coarse to abrasive sand, gravel, and silt.
To effectively remove the water-bearing ground, a large slurry chamber will combine the muck and bentonite while applying even pressure through the mud screen across the face. Two probe drills, mounted on spherical joints for increased range of motion, will probe ahead and inject pre-grouting if required depending on the geology and the need for interventions.
"Robbins fully expects that its entry into the slurry TBM market will gain quick acceptance, as has been the case with our entry into the soft ground EPB market," said Lok Home, Robbins President. Robbins has supplied three EPBMs to the Emisor Oriente stormwater drainage project in Mexico City and another for the city's Metro, two to the Delhi Metro in India, and one to a sewerage tunnel project in Sacramento, California, among several others.
The new sub-sea tunnel in southern China promises to ramp up the nation's steel output. The tunnel 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.
As the machine bores, it will line the tunnel with 450mm thick reinforced concrete segments in a configuration of five segments and a key in each ring. Active articulation will accommodate curves of down to 200m radius and prevent segment deformation.
Once complete in 2011, twin pipelines will run through the subsea tunnel to provide fresh water to the Guangdong Steel 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.
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