EUROPE’S LARGEST TUNNEL IS NOW A REALITY IN SOFIA CITY DOWNTOWN
« back 20.06.2011
On 20th of June 2011 a celebration for the finish of the works on the main stage of the construction of the most important Metro station of the Sofia city Metro project was held. Metro station 8 is placed on “Maria Louisa” Blvd. in front of the Central Department Store, which is the cross point of the Metro diameter I and Metro diameter II.
Beside the fact, that Metro station 8 is one of the most important in terms of its location, it is also one of the most complex underground structures ever built in Sofia city.
Archaeological discoveries imposed the means of the tunnel method to be used at the construction site. The archaeological layer remains at a level above the tunnel and the findings will be exposed and accessible to citizens. The metro station is located in the tunnel cut, which has the largest cross-section of all tunnels across Europe.
In order to build the facility in extremely complicated geological conditions a strengthening and construction of diaphragm walls was necessary, the tunnel level was reached through the North and South shafts. The drilling and the reinforcement was accomplished after The New Austrian Tunneling Method.
Traditionally, after this stage of the tunnel's construction, the tunneling companies celebrate the successful completion at that stage of work, which is actually the most difficult part of the construction of a tunnel. This particular stage of the work is considered the superior achievement in tunnel construction, as it requires the application of exceptional skills and great experience.
With the completion of the main tunnel construction – in terms of drilling and reinforcement, the specific underground works are considered done. The following stage is the finishing works and the equipment of the metro station.
The tunnel having length of 108 m., cross-section of 258 sq. m., height of 18 m. and width of 22 m., was finished in the extremely short time of about five months in the presence of aggressive high groundwater level, a very severe gelogy, parallel to that the archaeological layer - reaching a depth of about seven meters below ground zero, was discovered and preserved.
At the same time the top cover construction was installed, so that the roadway is restored.
Executors of the construction are two of the subsidiaries of “Euro Alliance Engineering” JSC:
part “Diaphragm walls” - "Stroyinject" JSC - the biggest company in Bulgaria for geological constructions having the most modern and diverse equipment at its disposal for the construction of diaphragm walls, sheet retaining walls, pile constructions and other types of soil retaining and fortification.
part “Tunnel Construction” - "Adval" JSC - the only Bulgarian company constructing major tunnels in various european countries /Germany, Spain, Greece to name a few/ for more than 20 years, as also working on latest major geotechnical projects in Bulgaria.
Hosting the event was dipl.eng.arch. Valentin Trashliev - CEO of "Euro Alliance Engineering" in the presence of the Bulgarian Prime Minister Boyko Borisov, Mayor of Sofia Yordanka Fandakova, Finance Minister Simeon Dyankov, Transport Minister Ivaylo Moscovski, also Stoyan Bratoev - executive director of "Metropolitan" EAD and other official guests.
More pictures from the event »
