e-w boring machines on course to hit the sweet spot on station wall | kolkata news - times of india

by:Gewinn     2019-08-20
Kolkata: structural engineers spent a few hours anxiously in the writer\'s building on Friday, observing for two centuries --
Old building with slight disturbance or signs of damage.
But at 18 metres underground, those who operate the tunnel rig (TBM)
There is no anxiety like a rotor drill going through the Earth at a steady rate.
For them, the challenge is about 60 metres ahead, where they have to hit the bull\'s eye to get into Mahakaran station. As Prerna —
Tunnel boring machine ~bound tunnel —
Arrive at the edge of Mahakaran station sometime on Tuesday and it will meet a 1-
The one-meter-thick concrete wall it had to go through entered the cave-like station unscathed.
This concrete guardrail is the north wall built by reinforced concrete at the station.
But it has two rounded points, called the soft eye, where the steel bars are replaced by a fiberglass-reinforced polymer (GFRP).
When Prerna reaches the station wall, it has to drill through a soft eye. Rachna —
Another boring machine drilling in Kolkata-bound tunnel —
The second soft eye will be worn out in 10 days.
\"TBMs can drill through rocks and concrete, but not steel.
Therefore, when the two tunnel ends of the underground wall of the station are constructed, four soft eyes are embedded on the wall to allow the double TBMs to enter and exit the station.
TBMs must hit the sweet head and pass through soft eyes with a diameter of 6.
The diameter is about 30 cm M, which is more than the diameter of the full section shield rotor blade.
Although normally, on a one-meter-long earth, it takes only half an hour for the whole rock tunnel to be excavated, and at the north end of Mahakaran station, it takes four painful hours for the monster machine to cross the concrete wall.
\"At this stage from halamidan to Binhai Avenue, each tunnel has to go through six concrete walls.
The last hole of these TBMs will be the west wall of the Marina Art Center station.
The two pairs of new TBMs will then begin the journey from the Marina Arts Center, through the east wall to the hole, to Sealdah, where they will enter the station through the west wall and complete the tunnel, the Kolkata Metro Company (KMRC)
Chief engineer.
Two TBMs have gone through the east and west walls of the Phoolbagan station and the East walls of the Sealdah station.
Overall, three pairs of TBMs will drill 22 holes through concrete, connecting the tunnel to six subway stations.
While drilling through concrete is a challenge, the bigger challenge is --
Drill out the sweet dots in the concrete.
\"In the construction of reinforced steel cages, the exact location of the two tunnels was calculated, using GFRP instead of the steel bars in the area where TBMs entered the station and exit.
The entire steel cage that forms part of the station wall with two soft eyes is put into the ditch and the concrete is poured into it.
When TBMs arrive, they will punch their eyes into the station, \"explains dewanji.
By the way, the progress of tbms is guided by the Internet
Link navigation and measurement software for coordinate input.
Executive Afcons can monitor every inch of progress on Google Maps
Germany\'s Transtonnelstroy, KMRCL, and the manufacturers of TBM.
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