New Delhi: The Delhi Metro Rail Corporation (DMRC), on August 21st, 2024 achieved a major construction milestone in Phase 4 with the completion of an underground tunnel between Chhatarpur and Chhatarpur Mandir Station on the Tughlakabad-Aerocity corridor, according to an official statement.
The breakthrough of the Tunnel Boring Machine (TBM) at the Chhatarpur Mandir site of the Delhi Metro took place in the presence of Vinai Kumar Saxena, Lieutenant Governor of Delhi, and Kailash Gahlot, Transport Minister of GNCTD. Naresh Kumar, Chief Secretary, GNCTD. Ashish Kundra, Principal Secretary to LG, Jaideep, OSD (UT), MoHUA also graced the occasion in the presence of DMRC’s MD, Dr Vikas Kumar and other senior officials.
A Tunnel Boring Machine (TBM) broke through this morning at Chhatarpur Mandir Station after boring an 865-meter-long tunnel. This tunnel breakthrough was achieved using a mammoth 97-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. The work on the other parallel tunnel on this section will be completed by September this year.
This new tunnel has been constructed at an average depth of approximately 15 metres. About 618 rings have been installed in the tunnel, which has an inner diameter of 5.8 metres.
The tunnelling work involved numerous challenges, such as shifting a 66 KV electrical HT line. Additionally, the TBM had to cross below the existing Yellow Line viaduct without disrupting Metro train operations on the Yellow Line.
The tunnel has been built using the proven technology of EPBM (Earth Pressure Balancing Method) with a concrete lining made of precast tunnel rings. These tunnel rings were cast at a fully mechanized casting yard set up at Mundka. The concrete segments were cured with a steam curing system to achieve early strength.
All necessary safety precautions were taken during the construction of the tunnel below the existing viaduct and built-up structures. 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 totalling 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 revolutionized tunnelling work worldwide, enabling tunnels to be bored without disturbing buildings and other surface structures.
TBMs are particularly useful for underground tunnelling work in congested urban areas. DMRC has been using TBMs for its tunnelling work since Phase 1. In Phase 3, when approximately 50 kilometres of underground sections were built, about 30 TBMs were deployed in the national capital. /BI
