What awaits “inna” and “elena”

The tunnel boring complex “Inna” started on August 22 from the round chamber on site 17. Together with “Elena”, which set off several months earlier, they will pass the stages from “Rzhevskaya” to “Savelovskaya” of the Big Ring. The output of the two TBMs is still a long way off, but the metro builders are preparing in advance. Artem Loza from SMU-8 told how chambers for dismantling shields are built from scratch.

TBM "Inna" starts from a round pit at site No. 17

Site No. 24 on Savelovsky Proezd is quite small. Nothing betrays the grandiose work that metro builders are doing underground. At a depth of 65 meters, they are preparing to meet the tunneling shields, starting from a round pit near the Riga overpass to the dead ends behind the Savelovskaya BKL.

According to the project, two dismantling chambers are provided here. The right one will receive the Herrenknecht S-771 TBM named “Elena” at the beginning of next year.

– The chamber is 40% ready, 37 half-rings have been mounted. We have started work on monolithing the tray part, reinforcing, installing metal insulation and concreting, - Artem Loza, head of section No. 4 of SMU-8, shows the frame of the future monolithic supports of the chamber, which will become the shoulders of the vault.

Head of section No. 4 SMU-8 Artem Loza

A young engineer took charge of the work on the site in March. During this time, his employees built an approach adit to the site of the future right chamber and passed the calotte. The space for installing the vault half-rings was developed using jackhammers. At the bottom of the tray we used a Brokk combine.

– The rock is very hard – limestone, dolomite. Sometimes the equipment took 10 hours to make a meter entry,” says Loza. The rock from the adit is taken away along sliding tracks on trolleys and shipped up through the mine shaft.

The construction of the left dismantling chamber, where the Inna TBM will arrive in a year, has not yet begun. But the approach corridor, about two hundred meters long, is already ready. All that remains is to concrete and clean up.

After digging through the left shield chamber, workers will begin constructing the ventilation tunnel, which will be adjacent to the ventilation unit on the surface. A drainage system will also be built. Excess water will be collected in the well and released to the surface.

Both shields will be disassembled in chambers and sent in parts to the launch site.  After this, the DMSC will be waterproofed and track concrete will be poured.

REFERENCE

The right running tunnel to the dead ends of the “Savelovskaya” BCL is being constructed by the Herrenknecht S-771 “Elena” TBM. The Shield launched on December 12, 2018. Its path will be 3.5 km, almost half has already been completed. The left stage is being built by the Herrenknecht S-772 “Inna” TBM, which left the round chamber on August 22. This stretch will be 3.2 km long. Both TBMs are located at a depth of 45 to 70 m, they will transit the stations under construction.