The Delhi Metro Rail Corporation (DMRC) has completed a significant tunnelling milestone on Phase 4’s Aerocity-Tughlakabad corridor, with a Tunnel Boring Machine (TBM) breakthrough at IGNOU Metro Station. This 1,475-meter-long tunnel, excavated at an average depth of 26 meters, is a crucial step toward enhancing Delhi’s metro connectivity.
Advanced Engineering for Deep Tunnel Construction:
- The tunnel was excavated using a 97-meter-long Tunnel Boring Machine (TBM), operating at an average depth of 26 meters, with minimum and maximum depths ranging between 15 meters and 36 meters, respectively.
- The excavation process involved installing 1,048 rings, each forming part of a 5.8-meter-wide tunnel, making it one of the deepest tunnels of the Delhi Metro.
- In comparison, the Magenta Line tunnel at Hauz Khas was constructed at a depth of 30 meters.
- The second parallel tunnel for down-line movement is scheduled for completion in March 2025.
Use of Proven EPBM Technology:
The tunnelling was executed using the Earth Pressure Balancing Method (EPBM), ensuring controlled excavation through complex geological conditions. Precast concrete tunnel rings used for reinforcement were manufactured at a mechanized casting yard in Mundka, where they underwent steam curing for accelerated strength development.
Despite encountering challenging geological conditions, including mica formations and hard rock, the tunnelling team successfully navigated the obstacles. The screw auger of the TBM sustained damage during the excavation but was efficiently replaced to ensure smooth progress.
Ensuring Safety and Stability:
- DMRC prioritized safety measures throughout the construction, especially considering that the tunnel passed beneath an existing metro viaduct and built-up structures.
- Advanced monitoring instruments were installed to track ground movements, preventing any structural settlements in the surrounding areas.
- As part of Phase 4 development, DMRC is constructing 40.109 km of underground metro lines, out of which 19.343 km are part of the Aerocity-Tughlakabad corridor.
- This ambitious expansion is set to further enhance connectivity in Delhi’s metro network.
Role of TBMs in Metro Expansion:
TBMs have revolutionized tunnelling in urban settings, allowing underground metro corridors to be built with minimal surface disruptions. The DMRC has extensively utilized TBMs since Phase 1, with over 30 TBMs deployed during Phase 3 to construct nearly 50 km of underground metro tunnels.
Conclusion:
The successful TBM breakthrough at IGNOU Metro Station underscores DMRC’s expertise in underground metro construction and its commitment to infrastructure development. With another breakthrough scheduled in March 2025, this milestone is a significant step toward completing the Aerocity-Tughlakabad corridor, enhancing urban mobility in the national capital.
Source: DMRC – Press Release | Images Credit: DMRC
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