Double work with concrete

The Kakhovskaya line continues to be integrated into the southern section of the Big Ring. In addition to the stations, large-scale work has been carried out on the reconstruction of existing and construction of new tunnels.

Experts note that building a new tunnel and installing tracks in it is much easier than working on old sections. The main work on the existing sections of the Kakhovskaya line is taking place in several sections at once: from construction site No. 8 to the Kakhovskaya station and further towards Kashirskaya. The areas here were divided by Tunnel 2001 and Tunnel Squad No. 6. Thus, TO-6 operates more than 3.5 kilometers of tunnels.

– The first thing you have to deal with is the difference in construction approaches. In Soviet times there were the same rules, but now they have become stricter. The safety requirements for the haul have increased,” explains Konstantin Borodynkin, head of the track base of section No. 3 TO-6. – It is easier to work in clean, dry tunnels.

The stages are simple and clear: after excavation, the tunnel is handed over to the contractor, then it is washed, the upper structure of the track is delivered, the rail-sleeper grid is installed, the formwork is assembled, washed again and handed over to the customer.

– Added to this list on the existing stretch is the cutting down of worn-out track concrete and problems with the rigid foundation. Over the course of its operation, it has become uneven, which creates problems already at the stage of the first flushing,” he continues. – And when constructing the upper structure of the track, there should be no foreign objects on the surface: no puddles, no debris. Cleanliness must be perfect; even the slightest defect is unacceptable. After this, you can import the necessary materials - rails, sleepers, concrete. Trucks and mini-loaders deliver them for subsequent stacking.

Another difficulty is the connection between the section under construction and the existing one. It has already been solved by connecting the tunnels. To date, 300 meters of tunnels have been reconstructed. It is planned to deliver another 400 by the end of April.

“Up to 70 people work around the clock,” notes Borodynkin. – We will speed up, including on the section from Varshavskaya to Kashirskaya, where the dismantling of the upper track structure is underway.

Tunnel 2001 took the adjacent section between the Kashirskaya and Varshavskaya stations.

“We have to remove 2.5 kilometers of old track concrete, “cure” all the leaks and lay new concrete,” says Evgeniy Bibikov, head of section No. 3 Tunnel-2001.

Work is also underway on the right section, which previously built the Herrenknecht S-290 TBM with the name “Marina” at the Zamoskvoretskoye electric depot. 500 meters of rail and sleeper grating have already been installed on the new site. Track concrete is laid by Tunnel-2001 crews. At the same time, the left distillation tunnel is being excavated. The shield covered 120 meters and installed 200 rings. There are still 670 meters left, which Marina will cover in early summer.

The biggest challenge at the current site is the changing geology. Instead of clay there is sand, into which the shield will “drive” after 50 meters. Now there are large boulders on the way of the Herrenknecht S-290. Because of the stones, the TBM had to be stopped briefly and caisson work was carried out.

“The cutting tool has not been changed yet; according to the regulations, this happens once every 400 meters,” continues Evgeniy Bibikov. – “Marina” will make its next stop after passing the 260th ring, only then we will replace the cutting tool - then the shield will reach site No. 19. After excavation, our teams will begin constructing a rigid base and laying the superstructure of the track.

In addition to panel tunneling at the depot, Tunnel-2001 crews are also working on other sections of the Kakhovskaya line. Thus, at site No. 16.2 they are finishing work on securing the foundation pit and dismantling old tunnels. At two more sites - No. 19 and behind the Kashirskaya station - monolithic work is underway.