In Jilin, one of the three provinces of Northeast China, a 7.9 m (26 ft) Robbins Hard Rock Main Beam TBM has achieved another national record for 7 to 8 meter (23 to 26 ft) machines! The machine bored 1,423.5 m in one month in December 2017, breaking the previously achieved monthly advance record of 1,230 m, which it set in spring 2017.

The tunnel, which is being bored as part of a water conservation project, will be 16 km (10 mi) long when complete. The contractor is Beijing Vibroflotation Engineering Co. Ltd. (BVEC).

Throughout its bore, the Main Beam is anticipated to encounter 24 faults within the tunnel and a maximum of 220 MPa UCS (32,000psi) rock. In order to handle the unstable rock, consisting of tuff, granite, sandstone, and andesite, the TBM is equipped with four rock drills, McNally pockets in the roof shield, a ring beam erector and a shotcrete system. The McNally Roof Support System was designed and patented by C&M McNally for exclusive use on Robbins TBMs. By replacing the roof shield fingers on a Main Beam TBM, the McNally system prevents rock movement in the critical area immediately behind the cutterhead support. Visit http://www.therobbinscompany.com. 03/18.