Underground construction / Technologies

Underground machinery

When tunnels are built by tunnelling, tunnel-boring machines (TBM) are deployed.

The TBM is assembled at the bottom of a pit which serves as the tunnel start point and which is covered with soil when the work is completed. At its front-end, the TBM has bits which cut rock. The machine begins to excavate soil and bears the overhead load, preventing the tunnel from collapse. As it digs the tunnel, the TBM cases its walls with liner segments. Then the space between the liners and rock is filled with concrete. The TBM moves deeper into the tunnel, using hydraulic jacks to push against the segments already in place. A special conveyor or pipeline removes the excavated soil beyond the machine confines.

To prevent the TBM from tilting due to the rotation of the shield’s cutting wheel, special-purpose trailing-support mechanisms are deployed outside the TBM body. The TBM position inside the tunnel is determined using laser instruments.

Mosmetrostroy uses equipment made by Lovat (Canada) and Herrenknecht (Germany). By tradition, Canadian and German-made machines are given female names. The six-metre TBM used to build the Butovskaya and Mitinsko-Stroginskaya lines is referred to as Claudia. A new machine, called Victoria (diameter 11 metres), dug the inclined tunnel for the escalators at the Maryina Roshcha station.

A Herrenknecht TBM 14.2 metres in diameter was deployed to build the Serebryany Bor tunnel. Another German-made machine is used by Mosmetrostroy in Turkey, where it is digging a tunnel under the Bosporus.

  • Lovat-made Claudia TBM competed tunnel between stations Myakinino and Strogino
  • Assembled Victoria TBM made by Lovat at the assembly shop in Toronto before shipment to Moscow
  • Assembly of Victoria TBM for inclined tunnelling at Maryina Roshcha Station

Having been commissioned by Mosmetrostroy, the Canada-based Lovat firm developed and manufactured a mechanised tunnel-boring complex 11 metres in diameter, which uses earth pressure balance. The new machine is to be used for digging inclined tunnels. The TBM is designed for tunnelling through various soils, including unstable. Its operating cycle comprises two stages: earthwork and lining.

When digging tunnels in unstable soils, Victoria is switched to the mode of full compensation of soil pressure. Pressure at the working face is maintained by matching the momentum of pushing cylinders to the rate of excavation.

Nowhere in world have such machines been used before. The use of such construction technology will make it possible to significantly reduce the timescale of engineering exits at deep-level stations.

“Lovat” presentation PPT, 15 MB, in russian