Mumbai-Ahmedabad Bullet Train project: The has released plan to construct a 16-km-long tunnel as part of the . Spanning 508 km, this is India’s first high-speed rail corridor, passing through Gujarat, Maharashtra and the Union Territory of Dadra & Nagar Haveli.
It plans to construct a 21-km-long tunnel for the between Bandra Kurla Complex (BKC) and Shilphata in Maharashtra. The tunnel will also include the country’s first 7-km-long undersea stretch beneath Thane Creek.
Of the total 21 km, 5 km of tunnelling using the New Austrian Tunnelling Method (NATM) has already been completed, while the remaining 16 km will be constructed using Tunnel Boring Machines (TBMs). According to NHSRCL, the lowering and assembly of the TBM has now commenced for the 16 km tunnel section between BKC and Sawli (near Ghansoli).
The 16 km tunnel will be a single tube tunnel of 13.1 m diameter to accommodate twin track. This tunnel will be about 25 to 57 meters deep from the ground level and the deepest construction point will be 114 m below the Parsik hill.
“The process began with the lowering of one of the six segments of the main shield, weighing approximately 170 metric tonnes. This segment measures about 8.66 metres in length and approximately 7 metres in width and was lowered at a depth of 56 metres below ground level—equivalent to a 20-storey building, at Vikhroli, Maharashtra,” the NHSRCL said.
NHSRCL has received two Tunnel Boring Machines (TBMs), with tunnelling operations set to begin after thorough testing and commissioning. To lower the TBMs, three shafts have been constructed:
TBM 1 will start from Shaft 2 at Vikhroli and will move towards Shaft 1 of Mumbai Bullet Train station at BKC while TBM 2 will start from Shaft 3 at Sawli and move towards Vikhroli.
“A dedicated casting yard covering an area of 11.17 Ha for casting tunnel lining for the 16 km TBM portion is already operational in Mahape, Thane district. 77,000 segments will be cast to form 7,700 rings. Special ring segments are being cast for the tunnel lining, each ring comprising nine curved segments and one key segment, with each segment being 2 meters wide and 0.5 meters (500 mm) thick,” it added.
