In mid-February the J. Kumar – China Railway No. 3 Engineering Group (CRTG) JV celebrated the breakthrough of its 6.68m diameter TERRATEC dual-mode hard rock TBM on Mumbai Metro Rail Corporation Ltd’s (MMRCL) Line 3 project, in India.
The machine is one of three new TERRATEC dual-mode TBMs being used by J. Kumar-CRTG to excavate portions of the line’s 4.94km-long twin-tube tunnel contract UGC-05 and 4.45km-long twin-tube tunnel contract UGC-06 (stretching from Dharavi Station to the CSIA International Airport).
“We congratulate TERRATEC on the performance of the Dual Mode TBM T62 and the completion of its first 690m drive of from the [CSIA] International Airport Station to Sahar Road Station,” said Haluk Emre, J. Kumar-CRTG’s Project Manager on Package 6. “The machine has travelled successfully through mixed geology and considerable water ingress and we credit TERRATEC’s TBM field service support experts for assisting our tunnelling operations with close monitoring throughout this period.”
The single shield TBMs are equipped to operate in either Open or Closed mode in the predominantly fresh and slightly to moderately weathered Basalt and Breccia expected on these contracts. The robust hard rock cutterheads are mounted with heavy-duty 17” disc cutters, which are interchangeable with ripper tools, and feature large bucket openings that provide a 10% opening ratio.
Other features include 2,000kW Electric Variable Frequency Drives – that allow the cutterheads to cut efficiently in harder rock zones at maximum speeds of 7rpm and deliver an exceptional torque of 8,500kNm to cope with more fractured zones of ground along the alignment – as well as active shield articulation and built-in two component backfilling grout systems.
In addition to the three new hard rock TBMs, TERRATEC has also supplied two re-manufactured 6.61m diameter mixed/rock EPBMs
(S63 and S64) to J. Kumar-CRTG in Mumbai, which have been put to work on a section of highly weathered ground on contract UGC-05. “The TBMs are performing very well,” says TERRATEC Site Operations Manager, Bill Brundan. “The five J. Kumar-CRTG machineshave excavated a total of more than 5.7km of tunnel to date.”
Afurther two new 6.68m diameter dual-mode hard rock TBMs are being used by the Hindustan Construction/Moscow Metrostroy JV to build the twin tunnels on the line’s 4.049km-long contract UGC-02. Both machines were deployed from the Chhatrapati Shivaji Terminal (CST) TBM launch shaft and are currently mining towards the Mumbai Central Station TBM receiving shaft, having now completed 3.7km of tunnel with progress rates of up to 525m per month.
In total, the seven TERRATEC machines have mined 9,462m (42%) of their planned drives to date.
When complete, Mumbai Metro’s much-anticipated Line 3 will be the first underground metro line in the city. The 33.5km-long line will connect Cuffe Parade business district in the far south to the Santacruz Electronics Export Processing Zone (SEEPZ)in the north-central with 26 underground and one at-grade station (see map).
Construction of the line is divided into seven tunnel-and-station packages that were awarded to five contracting joint ventures in 2016. These five contractors will deploy a total of 17 TBMs.