Work on the development of emergency exits is in progress at the construction of the tunnel under the Świna Strait. Two of them are built inside a tunnel drilled with CREG TBM machine at km 1 + 344 and at km 1 + 844 of the street.
The distance between the emergency exits is 500 m. To make a break for the development of the exit, it was important to get through the tunnel’s segment casing, make excavation and make a preliminary casing, which is made utilizing the supposed wet. To break the tunnel’s segment casing, an impermanent steel frame was introduced inside the TBM tunnel to strengthen the tunnel structure. The pre-casting of the break comprises of a shotcrete layer and steel ribs with a dispersing of 0.75 m. The objective casing will be made of reinforced concrete.
Freezing innovation was utilized to strengthen the ground. It depends on the consistent exchange of heat from the ground to the atmosphere. Therefore, the ground chills off and the water that fills the pores sticks to frame a layer of ice. The frozen ground transforms into a watertight irregularity. Dynamic freezing, for example, freezing which will permit the ground temperature to decrease to a temperature of about – 12˚C in the central part of the freezing coat, lasted a total of around 65 days. Thusly, uninvolved, for example keeping a low temperature while getting through the tunnel casing and developing the exit structure, will go on for around 100 days.
The whole course of opening and completing emergency exits has been divided into several phases. From cutting the opening in the built-up reinforced concrete casing of the tunnel, through disassembly of the casing illustrated with the notch and sectional excavation of the soil in a frozen square with the assembly of steel support outlines and the execution of a reinforced layer of shotcrete. This is to get the excavation and make the last reinforced concrete lining with protection.
As of now, at the EE1 emergency exit, uninvolved freezing is kept, including concreting the substrate for the installation of the base piece. The pre-casing has additionally been finished. Passive freezing additionally began at the EE2 emergency exit, where the excavation of the excavated material and the assembly of the underlying casing are as of now in the works.
Notwithstanding the two emergency exits EE1 and EE2, staircases are likewise made in the space of the beginning and getting chambers, which will connect the evacuation gallery situated under the street in the tunnel with the surface. This gallery is associated with two emergency exits carried out in the ground freezing innovation in the TBM tunnel. Staircases will likewise be emergency exits from the street level at the TBM tunnel entrances.
What else is occurring at the tunnel construction site?
On the island of Usedom, in the beginning, the chamber, the gathering, and prefabrication of the formwork for the transitional floor are in progress. In the part of the ramp and in the tunnel made with the roof technique, the whole structure is fixed, and simultaneously, the establishment of sidewalk reinforcement is in the works.
In the structure of the Service Center and Trafo TK3 Station, completing works and inner establishment works are done.
Work on inner designs is gone on in the getting chamber on Wolin Island. Diaphragm walls are sealed, just like the development of the ramp and tunnel made utilizing the ceiling technique. Technological channels are additionally made. Utilities and street frameworks are being based on the streets.
A retaining wall is being worked at the northern bypass, and cleaning and maintenance works are done on a continuous premise.