National High speed Rail Corporation Limited has achieved a major milestone today with the breakthrough of mountain tunnel for Mumbai-Ahmedabad High Speed Rail corridor project.
This is the first mountain tunnel which has been completed in a short span of 10 months.
The tunnel is located at around 1Km away from Zaroli Village of Umbergaon Taluka in Valsad district of Gujarat. The tunnel structure comprises of tunnel, tunnel portal and other connecting structures like tunnel entrance hood.
The tunnel is being constructed by New Austrian Tunnelling Method (NATM) which includes the following procedure:
- Marking of drill holes on the tunnel face
- Drilling of holes
- Charging of explosives
- Controlled Blasting
- Removal of muck (blasted rock pieces)
- Installation of primary support which includes steel ribs, lattice girder, shotcrete, rock bolts based on the type of rocks as assessed by geologist after each blast
Salient features of the mountain tunnel:
- Total Tunnel Length: 350 m
- Diameter of Tunnel: 12.6 m
- Height of Tunnel: 10.25 m
- Tunnel Shape: Single tube horse-shoe shaped
- Number of tracks: 2 Tracks
- MAHSR corridor will have seven mountain tunnels, which will be constructed using the NATM Method.