New Delhi (Metro Rail News): In the presence of Dr. Vikas Kumar, Managing Director/DMRC, and other senior officials, the Delhi Metro Rail Corporation (DMRC) today initiated a tunnelling operation using the Tunnel Boring Machine named “Bhoomi” to excavate a tunnel from Derawal Nagar to Pulbangash on the Magenta Line extension (Line-8) from Janakpuri West to R.K. Ashram corridor.
Between Derawal Nagar and Pulbangash, the tunnel spans around 3 km. The tunnelling would range in depth from 12.4 metres at Derawal Nagar station to 25.9 metres close to the Najafgarh drain. The TBM will therefore go across many geological layers below the earth.
In this phase, Delhi Metro is installing the BEAM (Bore Tunnelling Electrical Ahead Monitoring) System on all of its TBMs in a first-of-its-kind endeavour. It allows the TBM to anticipate in real-time the geological strata up to 20 metres in front of the machine’s cutter head face and anticipate any unexpected encounters with filled wells, cavities, and aquifers that might cause the earth to settle if the TBM hits them without the right treatment.
BEAM is a specialized ground prediction technique, known as non-intrusive focused-electrical induced polarization, developed specifically for the underground construction industry. It is applicable in various geological conditions, including hard rock, soft ground, and mixed ground, irrespective of the presence of groundwater or the type of boring machine being used (such as EPB, Slurry, Gripper, Single or Double Shielded TBMs). BEAM’s versatility allows it to be utilized independently of the TBM manufacturer.
The tunnel will traverse beneath numerous residential and commercial areas along GT Karnal Road, including Derawal Nagar, Rana Pratap Bagh, Shakti Nagar, Kamla Nagar, Ghanta Ghar, Subzi Mandi, and Roshanara Road. Currently, there are four Tunnel Boring Machines (TBMs) in operation across the city, specifically in the three priority corridors of Phase IV, namely Janakpuri West-RK Ashram Marg, Majlis Park-Maujpur, and Tughlakabad-Aerocity. As part of this phase, a total of 28 kilometers of new underground corridors are being constructed.