BENGALURU (Metro Rail News): Larsen & Toubro’s (L&T) Tunnel Boring Machine Lavi (DZ672) recorded its first breakthrough on 15th April at the underground MG Road Station for Bangalore Metro’s 21.386 km Pink Line.
This China Railway Construction Heavy Industry (CRCHI) slurry machine was commissioned from Shivajinagar Station in February 2021 to build the 1076m down-line tunnel for the 73.92 km Bangalore Metro Phase 2 project’s 2.755 km Package RT-02.
“The biggest issue faced when carrying out work using any TBM is the damage to the discs on the cutter head. In the case of Lavi, the discs were damaged more than that encountered with any TBM before. For every six metres drilled, four discs get damaged for any machine when passing through regular granite. But since it had to pass through a long stretch of Dolerite Zone, more discs got damaged. This forced us to stop, repair the discs and start again,” a BMRCL official said, TNIE reported.
“This happened nearly 200 times during the course of the drilling the 1076-metre stretch it completed. After some rings are laid, the machine comes face to face with a very hard surface at the core. This causes numerous damages'” he added.
From here on, TBM Lavi will now be dragged through MG Road’s station box for its final assignment to build the 1098m down-line tunnel towards Vellara Junction (National Military School). L&T hopes to complete that job in 331 days.