Mumbai, May 17 (PTI) The National High Speed Rail Corporation Limited (NHSRCL) on Sunday said the first Tunnel Boring Machine (TBM) cutterhead has been lowered at Vikhroli in Mumbai's eastern suburbs for
the construction of a tunnel as part of the Mumbai-Ahmedabad bullet train project.
The 13.6-metre diameter cutterhead, weighing 350 tonnes, which was lowered on Sunday, marks the final stage in the primary assembly of the TBM's main shield for the high-speed rail corridor project, an NHSRCL release said.
Two TBMs, each weighing more than 3,000 tonnes, are being assembled for the construction of a 16-km section of the 21-km-long Mumbai tunnel. The stretch includes a 7-km undersea tunnel beneath Thane Creek, which will be India's first undersea rail tunnel, the release added.
"The TBMs are the largest machines deployed so far for rail tunnel construction in the country. The cutterhead has been designed to excavate a single tunnel large enough to accommodate both the up and down lines of the bullet train corridor. The 350-tonne component arrived at the site in five separate shipments and was assembled using around 1,600 kg of high-precision welding," the NHSRCL said.
The unit has been fitted with 84 cutter discs, which would cut through the rock face, 124 scrapers that will clear the muck at the tunnel face, and 16 bucket lips for collecting and directing the excavated material into the pipeline system for removal from the tunnel, the release informed.
The TBM will excavate an approximately 6-km stretch from Vikhroli to Bandra Kurla Complex (BKC), passing beneath densely populated urban areas and the Mithi river before reaching the under-construction Mumbai bullet train station at BKC, the release highlighted.
"Various monitoring instruments are being deployed to ensure safe tunnelling and protect nearby structures during excavation. These include Surface Settlement Points (SSP), Optical Displacement Sensors (ODS), strain gauges and seismographs for vibration and seismic wave monitoring," it added. PTI KK BNM
