The National High Speed Rail Corporation Limited (NHSRCL) has completed the lowering of the cutterhead for the second Tunnel Boring Machine (TBM) that will be deployed for the underground section of the Mumbai-Ahmedabad bullet train corridor in Navi Mumbai.
According to officials, the 13.6-metre-diameter cutterhead, weighing nearly 350 tonnes, was lowered at Sawli near Ghansoli on Saturday. The activity marks a key stage in the assembly of the TBM’s main shield structure for the high-speed rail project.
The second TBM will undertake tunnelling work from Sawli towards Vikhroli in Mumbai. Earlier this month, the cutterhead of the first TBM was lowered at the Vikhroli site. Both tunnel boring machines will now undergo final assembly procedures and commissioning trials before excavation activities commence in the first week of July, NHSRCL said in an official statement.
The agency stated that the TBMs have been engineered to excavate a single tunnel capable of accommodating both the up and down tracks of the bullet train corridor. Each cutterhead has been fitted with 84 cutter discs, 124 scrapers and 16 bucket lips to facilitate excavation and removal of debris during tunnelling operations.
The two slurry-based Mix Shield TBMs weigh 3,080 tonnes and 3,184 tonnes respectively, while each machine measures 95.32 metres in length. The machines include multiple integrated systems such as the cutter wheel, main bearing, jaw crusher, erector, main shield, tail shield and four specialised support gantries.
NHSRCL stated that the TBMs are capable of operating at a maximum cutterhead speed of four revolutions per minute and can achieve excavation progress of up to 49 millimetres per minute while maintaining operational safety standards.
The machines are being assembled for the construction of a 16-kilometre section of the project’s 21-kilometre underground tunnel alignment. The stretch also includes a 7-kilometre undersea tunnel beneath Thane Creek, which is set to become India’s first undersea rail tunnel.
Source: ET Infra
