Robbins returns to Siberia for Severomuysky 2 05 Dec 2019

Forty years after the original machines worked in Siberia, two new Robbins TBMs are to return to Russia to complete work on the parallel tube of the Severomuysky railway tunnel on the BAM railway east of Lake Baikal. Two new 10.37m diameter Crossover XRE TBMs will complete the 15.5km long drive through mixed ground and fault zones that caused major geotechnical delays and troubles during excavation of the the first rail tunnel. In 1979, it was a 4.56m diameter Robbins double shield that was delivered to help bore the project’s service tunnel through the remote mountains of Siberia.

Original 4.56m double shield supplied for Severomuysky service tunnel in 1979

The new parallel tube for the rail line is needed to increase the carrying capacity on the current Baikal-Amur Mainline (BAM) railway through the area. Currently 16 million tonne of cargo is carried through the existing Severomuysky tunnel and the Russian Government wants to increase cargo carrying capacity by more than six times on the line. The largest global anthracite producer, Sibanthracite Group, is taking on the tunnel construction with management by VostokCoal Management Company. The companies, owned by Dmitry Bosov, aim to increase coal transport by up to 100 million tonne per year through the addition of the parallel tunnel.

“Robbins has established itself on the market as the best manufacturer of hard rock machines capable of providing the maximum penetration rate in hard rock. This is one of the determining factors in connection with the tight deadlines for the implementation of our project,” said a representative of Sibanthracite Group. “Also, Robbins is the only manufacturer to build the Crossover TBM. A Crossover type machine is selected to excavate through difficult heterogeneous geological conditions from unstable waterlogged soils to hard rock. The Crossover machine is able to operate in two modes: open mode, used while boring in hard rock formations, and closed EPB mode when boring in unstable water-logged soils.”

The lessons learned during the first Severomuysky experience, among them the importance of probe drilling, consolidation grouting, and preventing a shielded machine from becoming stuck in fault zones or squeezing ground, are all part of the Crossover TBM solution. “I was a young engineer working at Robbins when the double shield TBM was delivered for the first tunnel,” said Robbins President Lok Home, “so it is a special honour to bring this new technology to the second Severomuysky tunnel in Siberia. Per the contract the Robbins Crossover TBMs are made to bore in highly variable ground conditions while maintaining good advance rates. With our latest technology we hope to again prove TBMs are the better choice over drill+blast when difficult ground conditions are to be encountered.”

New XRE TBMs will have a belt conveyor and a switch-out screw conveyor for challenging conditions

The machines will be designed for varying water pressures, ranging from 5 to 20 bar. They will feature water inflow control, a system that seals off the face and periphery and creates a safe working environment in which to dewater and consolidate ground. The machines will feature probe drill ports and capabilities for 360-degree probe drilling and grouting ahead of the excavation face, while the Robbins torque-shift system will enable the machines to bore through collapsing ground and other situations that demand high torque. The machines will also be designed with a belt conveyor in hard rock mode that can be switched out with a screw conveyor to better handle excavation conditions in soft ground.

Crews will bore through the Severomuysky Ridge, a mountain range in Buryatia and part of the Stanovoy Highlands, which separates the basins of the Upper Angara and Muya Rivers. “The second Severomuysky tunnel is located in one of the most geologically active areas of our planet, on the north-eastern flank of the Baikal rift zone,” said the Sibanthracite representative. “The region is characterised by high seismic activity, difficult geological and hydrogeological conditions against the backdrop of a harsh climate where the summer period lasts only 80-100 days and summer temperatures of +39°C in summer fall to -58°C in winter. The construction work on the portals is complicated by the presence of permafrost as well.”

Other aspects of the supply include a continuous conveyor for muck removal, rolling stock, spare parts, and cutting tools. Construction of the new tunnel is expected to begin in 2020 and take five years.