New Robbins Support System Gains Ground at West Qinling

The new roof shield canopy contains mesh pockets, rather than fingers, for installation by workers under the safety of the shield structure. Other design aspects include improved ring beam building, separate roof and probe drills, and materials handling.
Ground in the tunnels consists of 30 to 80 MPa (4,300 to 11,600 psi) UCS sandstone and phyllite rock beneath more than 1,400 m (4,600 ft) of cover. The corresponding ground support program consists of continuous mesh and rock bolts, with either ring beams or steel straps, for the length of the tunnel. "We believe this systematic use of mesh with roof bolts and steel straps will be adequate support for the geology," said Brian Khalighi, Robbins Vice President - Kent, WA, USA.

Should extremely poor ground be encountered, the mesh pockets can be relatively easily modified to use the McNally Support System, patented by C&M McNally Engineering of Toronto, Ontario, Canada for exclusive use with Robbins TBMs. The McNally System utilizes steel or wood slats to provide continuous support along the roof area of the tunnel, protecting workers from falling rock.

The two machines, for contractor China Railways 18th Bureau (Group) Co., were assembled at a local workshop and transported to the jobsites, where they were assembled on bridges spanning a deep valley. The first machine, for the Left Line, was launched at the end of June and has excavated over 100 m (330 ft) after being walked through a 2.0 km (1.2 mi) long adit tunnel. The second machine, for the Right Line, was launched on July 17. The TBM tunnels are just 40 m (130 ft) apart and are located approximately 1,000 m (3,280 ft) above sea level, about halfway up Qinling Mountain.

The parallel rail tunnels will be used for freight, and will link the city of Longnan with the towns of Waina, Luotang and Fengxiang within Gansu Province. The West Qinling tunnels are part of the Chinese Government’s Lanzhou to Chongqing Railway, a massive 820 km (500 mi) long scheme that will link the capital of Gansu Province (Lanzhou) with southwestern Chongqing, a mega-city of over 35 million people. The new railway, at a cost of USD $11.3 billion, will shorten transport times from 17.5 hours to 6.5 hours and enable an annual freight capacity of 100 million metric tons (110 million US tons). Trains will run on the double track lines at 160 km per hour (100 mph), with a 50-train daily maximum. The entire railway is expected to open to traffic in 2014.


Contact:
The Robbins Company
Brianna Home
29100 Hall Street
Solon, OH 44139, USA
PH.: 253.872.4484
E-Mail: homeb@robbinstbm.com
Internet: www.robbinstbm.com