Mixed ground TBM ready for Mumbai Metro 21 Sep 2017

The first of two Robbins slurry TBMs has passed factory acceptance tests for its work on the Mumbai Metro Line 3 project. The rebuilt 6.65m diameter will work on contract UGC03 for the Dogus-Soma JV (DSJV), and will begin excavation in late 2017. Factory acceptance of the second 6.65m diameter slurry TBM for the same Dogas-Soma JV will be completed by the end of 2017.

Officials celebrate factory acceptance testing

The two machines will excavate the parallel 3.5km long running tunnels between Mumbai Central and Worli Station sites, passing through three intermediate cut and cover stations on the way. Ground conditions consist of fresh to weathered basalt and breccia up to 100 MPa UCS with water pressures up to 3 bar.

The on-time delivery of the first machine is just the beginning of a partnership that will span years. “Robbins has been helpful since the inception of the project and will be our partners until the end of the contract," said DV Raju, Senior Vice President for SOMA. The Robbins’ presence in India, including field service crews, will be a great help for us,”

The JV selected slurry machines for its contract due to the challenging ground conditions expected. “I have worked with Slurry TBMs on similar geology globally and they have real power and will suit the hard rock geology of our Mumbai Metro contract 3," said Tamay Sayin, Project Manager for DSJV. "The water table and variable geology, especially basalt of higher hardness, can be easily tackled by Slurry TBMs.”

(From left to right) DV Raju, Senior Vice President-SOMA, Kapil Bhati, Managing Director-Robbins India, and Tamay Sayin, Project Manager-DSJV

The cutterheads of the machines are fitted with wear protection, wear detection bits, and Robbins 17in disc cutters. Grizzly bars will limit the size of boulders that can enter the cutterhead to 250mm. The slurry systems include rock crushers as well as abrasion-resistant plating in high-wear areas.

The two TBMs are the first of a total of four Robbins machines being provided for the Mumbai Metro Line 3 project. Another two 6.65m diameter Crossover XRE machines will excavate parallel 2.8km tunnels on a separate contract.

“Mumbai Metro is one of the most prestigious metro works in the country, and the Robbins involvement in providing suitable machines and associated services is an honor,” said Kapil Bhati, Managing Director for Robbins India.

The 33.5km long Line 3 of Mumbai Metro being constructed by the Mumbai Metro Rail Corporation (MMRC) will consist of 26 underground stations and one at-grade station that will reduce heavy traffic and rail congestion between Bandra and Churchgate areas of the city. A total of 17 TBMs are being procured to excavate various sections of the tunnels, which will be excavated at average depths of 15m to 25m below the city. The entire line is expected to be operational by 2021.