Contractor, Tata Projects Ltd has celebrated the assembly of the third of five ordered 6.61m diameter Terratec EPBMs for use on its underground works contracts on the Chennai Metro Rail Phase-II Corridors India. Terratec is supplying five out of the seven TBMs required for the package.
The TBMs are being used for Chennai Metro Rail Limited (CMRL) to build Phase 2 – Corridor 3, Package-TU01 from Venugopal Nagar Station to Kellys Station. The work involves the construction of a 9km of twin tunnels for a total of 18km.
Dispatch of the TBMs started in 2022. In October 2022, TBM S96 was the first launched of all the machines and along with TBM S97, both machines started excavation towards Madhavaran High Road. While TBM S98 had also started excavating from the same shaft – Madhavaran Colony moving towards Venugopal Nagar (of Line-5) to Kellys Station. TBM S99 on-site assembly is currently underway.
Meanwhile, the fifth machine (S81B) has passed the factory acceptance test (FAT) in Pune for Package TU01 of the 118.9km Chennai Metro Phase 2 project. The TBM was refabricated as per the ITA guidelines which have been introduced for the first time in India. Back in 2021-2022, this Ø6.61m EPBM was used to build a 2144m tunnel between Swargate and Budhwar Peth stations for Pune Metro Phase 1 project’s 16.6km Purple Line.
The Chennai Metro project Phase 2 – Corridor 3, Package – TU01 includes the construction of diaphragm walls and entry & exit structures of Madhavaram Milk Colony Station, Murari Hospital Station, Ayanavaram Station and Purasaiwakkam High Road Station, including the launching and retrieval shafts at the above stations. Major challenges of the project include tunnelling beneath historical structures in built-up areas.
The TBMs have versatile mixed-ground dome-style cutterheads that have proven to work extremely effectively in mixed geology – which includes mainly sand, silt, clay on the tunnel drives with occasional weathered rock. 1,400mm wide by 275mm thick universal reinforced concrete lining rings are installed as the TBMs progress which consist of five segments plus a key.