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Shielding has been completed of the inclined tunnel at the Maryina Roshcha Station: a Lovat TBM 11 metres in diameter was used to put in place 94 segments of reinforced concrete rings in the escalator tunnel. Now the shielding complex is being dismantled and lifted in sections to the surface through the tunnel it dug. During the dismantling, the tunnel is being held in place by the shield frame.

Using state-of-the-art technologies for the construction of various underground facilities, OAO Mosmetrostroy was the first in Russia and in world to engineer an inclined metro escalator tunnel by means of a mechanised tunnel-boring complex using earth pressure balance. Having been commissioned by Mosmetrostroy, the Canada-based Lovat firm developed and manufactured a tunnel-boring complex with an outer diameter of 11 metres, to be used for building inclined tunnels. Traditionally, inclined metro tunnels are dug in Moscow using mining techniques in a pre-frozen body of soil since the tunnel penetrates layers of low-stability and waterlogged soils. The mechanised complex produced is designed to dig tunnels in a variety of soils, including unstable ones. The complex’s operating cycle comprises two stages: excavation and lining. When digging tunnels in unstable soils, the complex 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 by spiral conveyor from the rotor chamber. Soil having been excavated segment-deep, liners and distance bolts are put in place.