Since mid-spring, a picture that is unusual even for experienced metro builders has been opening up in the Rubtsovskaya station pit. Taking soil from it, Stroymekhservice machine operators reached the level of the vaults of two reinforced concrete tunnels, already laid in the depths parallel to the longitudinal axis of the future station of the Big Circle Metro Line. A correspondent of our newspaper visited the construction site.
Since the meeting of Stroymekhservice specialists with the tunnels, the scope of work there has narrowed. The excavator bucket only bit into the intertunnel pillar, as if laying an unusual trench with rounded walls in the limestone layers. At the same time, the tracks of the vehicle gradually reached the design mark, on which the covering of the passenger platform will appear. In the meantime, Ilya Shevlyakov’s site suspended further development of the soil in this part of the pit and joined in the dismantling - within certain boundaries - of the tunnels he had excavated.
They were passed by the section of Vasily Kostromenkov from TO-6, who, starting from the former Metallurg stadium, carried two of his Herrenknecht tunnel-boring mechanized complexes without stopping not only beyond the Rubtsovskaya, but also beyond site No. 18, located on the opposite bank of the Yauza. This option for organizing end-to-end tunneling gave the tunnelers a gain in time.
First, mechanics dismantled hundreds of bolts holding together the reinforced concrete lining elements. This was done by the same workers who drove them into rings several months ago. But the integrity of the structure remained intact even without fasteners.
Then Viktor Karavaev’s section from TO-6 began working on the tunnels, initially working – together with Stroymekhservice specialists – on the Rubtsovskaya station pit, ensuring its reliable fastening.
The site manager entrusted the removal of heavy structures from the pit to the team of Alexander Larin, whom he had known for many years from his work at SMU-3. Since the end of the 2000s, Larin’s name has resounded loudly throughout Mosmetrostroy. He is known as one of the best specialists in the construction of single-vaulted shallow stations. In 2012, Alexander Alekseevich was awarded the high title “Honored Builder of the Russian Federation.”
In the pit of the future Rubtsovskaya station, Larin’s team has at its disposal both a tower crane and an excavator with a replaceable working tool. Among the available devices, there is only a light aluminum ladder, so that, being inside the ring of the tunnel lining, one can reach the upper side blocks.
In addition, local craftsmen came up with and produced several copies of a simple device in the form of a screw with eyes - it is fixed in the mounting holes of the block that is being prepared for lifting.
The foreman usually stands at the top, at the side of the pit. From there he can clearly see both the slingers and the crane operator.
“The most difficult thing to dismantle is the topmost block of the ring, or the lock,” says Larin. - Because it is tightly clamped on all sides. And the easiest way is to break the “cap” of the tunnel with a hydraulic wedge mounted on the boom of an excavator. The following blocks are easier to deal with. It happens that it is enough just to pick up the block with a ladle to make it move a little. As a last resort, we hit it with a hydraulic wedge. Next – we hook up the cleats, give a preload and – vira!
The lining rings are dismantled one by one, first from one tunnel, then from another. This is more convenient from the point of view of the following operations - excavating soil and preparing the base of the tray. And Alexander Larin’s team wants to quickly get down to their main business - the construction of monolithic structures. But at this stage, not everything depends only on herself. The speed of dismantling must also be coordinated with the installation of the foundation pit, and this, in turn, depends on the availability or delivery of materials.
Dmitry Rubinchik, deputy chief engineer - head of technical production department of TO-6 Metrostroy LLC
The Rubtsovskaya pit was crossed by city communications: pressure sewer pipes, a collector, power cables - before relaying them, it was impossible to develop the pit, concrete the tray and drag the panels starting from site 5.2 along it. In addition, it would be necessary to lay a thickened reinforced concrete slab for the stop frame, install starting rings for inserting the shield, and equip a mining complex to continue excavation to the site where the process chamber is being constructed. Such additional work would prevent the construction of a significant part of the station for a long time. This was avoided thanks to the passage of shields through the future pit of Rubtsovskaya.