The Delhi Metro on Friday started a tunnelling drive by the Tunnel Boring Machine named “Bhoomi” from Derawal Nagar to Pulbangash on a forthcoming corridor under its 'Phase IV' project, officials said.
The TBM was launched at Derawal Nagar metro station site on 'Line 8', being built from Janakpuri West to R K Ashram, in the presence Delhi Metro Rail Corporation (DMRC) Managing Director Vikas Kumar and other senior officials, they said.
The length of the tunnel is approximately 3 kilometres. The depth of tunnelling will vary from 12.4 meters at Derawal Nagar station up to 25.9 m near the Najafgarh Drain.
Therefore, the TBM will traverse through varying geological levels underground, the DMRC said in a statement.
In a first-of-its-kind exercise, the Delhi Metro is equipping all its TBMs with the BEAM (Bore Tunneling Electrical Ahead Monitoring) System in this phase, officials said. It enables the TBM to predict on a real-time basis the geological strata, up to 20 metre ahead of the machine's cutter head face, and predict any unexpected encounter with filled wells, cavities, and aquifers which may lead to settlement over the ground if hit by the TBM without proper treatment, the statement said.
The BEAM system is a non-intrusive ground predicting technique especially designed for the underground construction industry.