Larsen & Toubro’s Tunnel Boring Machine Lavi (DZ672) on April 15 recorded its first breakthrough at the underground MG Road Station for Bangalore Metro’s 21.386 km Pink Line (Reach 6).
A BMRCL official speaking to TNIE explained the terrain challenges faced by the team:
The biggest issue faced when carrying out work using any TBM is the damage to the discs on the cutter head. In 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 number of discs got damaged. This forced us to stop, repair the discs and start again.
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
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.
Lavi’s sister machine, TBM Avni, working on the parallel tunnel arrived at MG Road in January 2022 and started its second drive towards Vellara Junction on March 4.
With this development, approximately 36% of tunneling work for Phase 2 (total scope: 20,855m) has been completed with 7 out of 26 breakthroughs recorded: 3 on Package RT-01 by Afcons, 2 on RT-02 by L&T, 2 on RT-03 by L&T, and 0 on RT-04 by ITD Cementation.
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