The Delhi Metro Rail Corporation (DMRC) on Wednesday achieved a significant construction milestone in Phase 4 with the completion of the longest underground tunnel between Tughlakabad Airforce Launching shaft and Maa Anandmayee Marg on the Tughlakabad-Aerocity corridor.
The breakthrough of the Tunnel Boring Machine (TBM) AMRIT at the Anandmayee Marg site of the Delhi Metro took place in the presence of Rajiv Dhankher, Director Projects and Planning, DMRC and other senior officials.
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“A TBM broke through this morning at Maa Anandmayee Marg Station after boring 2.65-kilometre -long tunnel. This tunnel breakthrough was achieved using a mammoth 105-metre-long TBM. Two parallel circular tunnels for up and down movement are being constructed on this stretch as part of the Aerocity–Tughlakabad corridor,” said Anuj Dayal, Principal Executive Director, Corporate Communications, DMRC.
The official said the breakthrough on the other parallel tunnel is expected to be achieved in January, 2025.He said that this new tunnel has been constructed at an average depth of about 16 meters. About 1,894 rings have been installed in the tunnel, with an inner diameter of 5.8 meters.
“The tunnelling work posed significant technical challenges, including the relocation of a sewer line, navigation through hard rock strata etc. The tunnel has been built using the proven technology of Earth Pressure Balancing Method (EPBM) with a concrete lining made of precast tunnel rings. These tunnel rings were cast at a fully mechanised casting yard set up at Mundka. The concrete segments were cured with a steam curing system to achieve early strength,” the official said.
Pointing out that all necessary safety precautions were taken during the construction of the tunnel below the existing built-up structures, he said ground movements were monitored with highly sensitive instruments fixed on nearby structures, ensuring that there was no settlement anywhere.
As part of the Phase 4 work approved so far, 40.109 kilometres of underground lines are being constructed. The Aerocity-Tughlakabad corridor has underground sections totaling 19.343 kilometres,
A TBM is a machine used to excavate tunnels with a circular cross-section through various soil and rock strata. They can be designed to bore through anything from hard rock to sand. TBMs have revolutionised tunneling work worldwide, enabling tunnels to be bored without disturbing buildings and other surface structures.
