From February 16 to 25, the Herrenknecht S-755 mechanized tunnel boring complex, constructing the left section from Rubtsovskaya to Stromynka, will pass a section of the track under the oldest station metro.
At the construction site where the Stromynka BKL station is being built, they are preparing to meet the shields moving from Rubtsovskaya. Natalya will be the first to cross the metro zone. It will pass under Sokolniki station, through the future vestibule No. 1 and the platform part of Stromynka. The TBM will exit into a specially prepared chamber on the site of vestibule No. 2, leading to the park.
Its construction was preceded by a lot of preparatory work: relaying of utilities, construction of the enclosing structure of the pit from secant and soil-cement piles. Soil development began in October last year.
Specialists from Stroymekhservice Metrostroy LLC (SMS) were responsible for the excavation work. The difficult geological conditions encountered during excavation only accelerated the process. As a result, the task was completed on January 16 - two weeks ahead of schedule.
– According to the estimates and projects, work here was only provided for with a bucket. But we encountered strong limestone. We had to change the technology and use a second excavator with a hydraulic wedge,” explained Ilya Shevlyakov, head of SMS section No. 2. – Two engineering and technical workers and machinists were constantly working at the site. The total volume of developed soil was 52 thousand m³.
The firing system for fastening the pit was carried out by SMU-12 employees. Now they are concreting a temporary tray. This is a structure for receiving and launching shields, which is subsequently dismantled. The work is led by the head of section No. 5 of SMU-12 Sergei Toroschin. They are planned to be completed at the end of February.
Then TO-6 specialists will prepare a reinforced concrete bed in the chamber and install guides along which the shield will be dragged from the exit wall to the entrance to the next one. The distance between them will be 60 meters.
For SMU-12, the most difficult task in preparing for the exit of the shields was the construction of the end wall of the enclosing structure of the pit from the side of Rusakovskaya Street, where the vestibule No. 1 is planned. It is through this that the TBMs will enter the station complex area.
It took a year to build a wall 30 meters long. We had to occupy the first and second lanes of the highway out of the existing three. Design and administrative tasks took up a lot of time. For example, the issue of using the roadway was decided at the level of the metropolitan government.
The wall is made of secant piles with a diameter of one meter. The jet was completed, the weights were arranged.
– We went out onto the roadway twice to install secant, tangential and soil-cement piles. They took out part of the drain and the 10 kV cable line. There is also a third exit to complete the work on removing communications,” said Deputy Chief Engineer of SMU-12 Egor Gridasov.
From site No. 18, under the leadership of the head of the TO-6 section Vasily Kostromenkov, “Natalya” passed a difficult path with extreme slopes and radii. The shield has overcome many combined geological layers of different hardness: limestone, alluvial deposits, clay, marl. In addition, along the way there was an erosion zone with a large water influx - a residual phenomenon from the old underground river.
Before the final push, when only 20 meters remained to Sokolniki, the cutting tools (cutters and cutters) were replaced on the TBM, the brush seal was updated, and additional equipment was installed. In case of water influx, pumps and a polymer composition were delivered.
Next, “Natalya” awaits the most important part of the journey – the passage under Sokolniki. The distance from the shield gap to the existing metro station will be only six meters. The TBM will arrive at the prepared chamber approximately at the end of March. Then the shield will lead SMU-1 towards the Rzhevskaya station. The Herrenknecht S-770 “Sofia” TBM, which is constructing the right running tunnel from Rubtsovskaya to Stromynka, will approach Sokolniki station on April 6 of this year.
Konstantin Sysoev,Deputy Chief Engineer of Metrostroy Tunnel Squad No. 6 LLC
The movement of billboards in an area of dense residential development, traffic flows and just a few meters from one of the first metro stations in the capital imposes its own difficulties.
At site No. 8, a 24-hour headquarters will be organized to monitor the excavation with representatives of the Moscow Metro Directorate, Mosinzhproekt JSC and our engineering and technical workers. Soil will be shipped in buckets with constant monitoring of its quantity, so that in case of overuse, measures can be taken promptly. At sites No. 8, 18 and Sokolniki station, points with emergency supplies of materials will be established in case of unforeseen situations.