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On September 22nd, the hard rock/slurry TBM Urja (DZ670) manufactured by China Railway Construction Heavy Industry Cooperation Limited (CRCHI) firstly achieved the breakthrough from Cantonment Station to Shivaj Nagar Station among the 9 TBMs in Phase-2 of Metro project in Bangalore, India.

It is acknowledged that Bangalore metro project with frequent stratum variations is one of the most challenging metro construction projects which use TBM method. The total lenght of the section is 855 meters, among which 250 meters surrounding rock strength is up to 200 MPa of a full section hard rock, 350 meters compound stratum with a large number of boulders, hard bottom and soft top, and 255 meters consisted of sand or backfill stratum. Apart from that,  the TBM passed through the shallow buried depth section of the old town of Bangalore city with dense residential areas. The minimum buried depth is 7.6 meters and the geological conditions are very complicated.

In order to overcome the variable geology and shallow buried depth, CRCHI has carried out a number of specific designs for this hard rock/slurry TBM to ensure smooth tunnelling under complicated geological conditions. The TBM is equipped with heavy composite cutterhead, active hinge + stabilizer, advanced geological detection and grouting system, excavation management system and others.

CRCHI supplies 4 set of TBM for this project and the Urja TBM will be transported to the launching shaft at the north end of Cantonment Station, where it will continue to construct a tunnel between Cantonment and Pottery Town Stations in the city.