Autostrada has completed the dismantling of the emergency section and has begun strengthening the parts of the old subway tunnel that are adjacent to the emergency section on both sides with a reinforced concrete "jacket"


The supporting "shirt" is a reinforced concrete pipe that will completely repeat the rounded geometry of the tunnel, which will generally strengthen the problem area. Before the installation of tunnel reinforcement with a reinforced concrete "shirt" began, a number of preparatory works were performed: the surface of the concrete tubing was thoroughly cleaned to reveal flaws and deformations of the annular frame. Since the tunnel is flooded, it was necessary to carefully seal all the seams, the smallest cracks and crevices in the frame. Therefore, first, through special injection packers pre-installed in the frame of the tunnel, a two-component polyurethane resin was injected, which increases several times when in contact with water and fills the smallest pores. After that, a reinforced frame was installed in the tubing caissons and the process of shotcrete (spraying of "wet" shotcrete) - spraying of ready-made plastic concrete solution on the prepared surface - was started. How it happens: the concrete mixture with water and plasticizers is fed into the receiving hopper of the pump and transported to the shotcrete nozzle, where it is mixed with hardeners and fed to the surface under high pressure. The plastic concrete mortar during "wet" shotcrete filling well fills the caissons (recesses) of the tubing and locks in the already partially hydrated cement, which significantly improves adhesion to the surface of the tunnel frame. Upon completion of shotcrete, we will arrange waterproofing, install metal radial frames and begin the direct construction of the tunnel reinforcement with a monolithic sprayed concrete "shirt", which will also be performed by the method of "wet" shotcrete. Work on the restoration of the tunnel between "Lybidska" and "Demiivska" is carried out 24/7!