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Main beam TBM makes great time in Mumbai 25 Feb 2014
Desiree Willis, Technical Writer, The Robbins Company
One of the longest and deepest water supply tunnels in Asia has been completed and in record time. On 21 January 2014, a 6.25m Robbins main beam TBM completed a 8.3km water supply tunnel in Mumbai, India, exhibiting high performance operation throughout and achieving impressive advance rates along the way.
Well earned celebrations after 8.3km of tough tunnelling

Well earned celebrations after 8.3km of tough tunnelling

JV contractor Unity-IVRCL (UIJV) was pleased with the hard rock machine and the continuous support provided by Robbins during the project. Pravin Titare of Unity said "the Robbins machine was good in hard rock and we reached high rates of 870m in one month and 58m in a day, both records for TBM tunneling in India. We were able to achieve this due to the good performance of the machine and the continuous conveyor muck haulage system that was used in place of conventional methods."
Robbins supplied the TBM and the conveyor system to the project, and provided field service personnel to monitor the equipment and assist with daily upkeep and inspection. "The Robbins crew helped us commission and start boring on schedule," said Titare, "and the Robbins TBM operators did a great and skillful job maintaining tunnel alignment. Because of this, UIJV received a good reputation towards our client Municipal Corporation of Greater Mumbai (MCGM)."
  • The 6.25m diameter Robbins TBM
  • Tunnelling advanced from an access shaft of more than 100m deep
  • The 6.25m diameter Robbins TBM operated more than 100m below ground

Although the machine was ultimately a success, it did experience its fair share of challenges during its 21 months of operation. Difficult ground conditions, including basalt rock, fractured ground, and heavy water inflows, were encountered throughout the tunnel.
Contractor delighted with Robbins support

Contractor delighted with Robbins support

In explaining how challenges were overcome, Bipin Arey of IVRCL said, "the geology was particularly bad at times. Our team took all precautionary measures and advanced slowly. We maintained good ventilation throughout the execution phase and utilized a good dewatering system."
Ground support played a critical role, said Titare. "The TBM was very safe in the adverse geological conditions. The rock support system and ring beam erector were helpful in reducing downtime and allowing us more production time." Challenging ground conditions, combined with the depth of the tunnel at 109m below ground surface, made the machine's advance rates especially notable.
Now completed, the water transfer tunnel will provide clean drinking water to the 20.5 million residents of Mumbai and secure a consistent flow, even during the seasonal monsoons that formerly contaminated the city's water resources.
References
Deep drive record-setting in India - TunnelTalk, November 2013
Deep level drive for Robbins TBM in Mumbai - TunnelTalk, July 2012

           

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