St. Petersburg resumed tunneling for Begovaya subway station
On the 21st of June after scheduled repair of the Nadezhda shield cutting element, the tunneling resumed on Nevsko-Vsileostrovskaya subway line portion from Begovaya to Novokrestovsky station.
Construction of Begovaya station
Shield repair works had been scheduled for after it passed Begovaya station. On the 5th of June the shield set up the last rim at the station and was halted (730 tunnel rims have been assembled so far, the length of the tunnel is over 1,300 m).
Repair works were conducted directly in the tunnel. A meter-wide vertical borehole to the surface provided ventilation, and the working face was reinforced. This allowed the builders to perform welding and replace cutting parts without caisson pressure.
The cutting tool parts were completely replaced, the most worn-out parts of the rotor received hard-alloy facing, maintenance of vertical and tunnel conveyors was performed, additional drive was added to the tunnel conveyor. An auger plate damaged in boulder zone was repaired.
During the repair works on the shield, the tunnel received hard floor base and ventilation chute bridging, rail-laying work began.
In addition, construction of dismantling chamber at the tunnel destination point of the near Primorskaya station continued.
Construction of Novokrestovskaya station
In the next six months the shield will advance by 600 m to a point under the Neva river and then by 1,300 m to Novokrestovskaya station, there to undergo complete repair of cutting parts. The logistics of servicing the tunneling operation will also change, tunneling maintenance will be provided from Novokrestovskaya instead of the starting ditch.
The tunneling will end when Primorskaya station is reached. The shield will travel some of the way under the Gulf of Finland.