Year
2024
Location
IMPHAL
Type
Goverment
Client
VENSAR
Services
Heavy Water Ingress Control
Grouting Under Pressure
Tunnel Lining Protection
Geotechnical Risk Mitigation
The T-12 Audit Tunnel – a critical railway infrastructure project executed under extreme geological and hydrological challenges to ensure safe connectivity in the Northeast.
project details
- The audit tunnel having total Length of 1400 meters with excavated diameter of 8.5 meter constructed at Imphal.
- The audit tunnel was constructed in the challenging geology with saturated media. The presence of water media can cause problems in the excavation.
- The stability of the tunnel is affected by several types of discontinuities (joints, faults, and shear zones).
Field Condition
- The heavy water ingress was mainly observed from Chainage 1080 to 1440m. Similarly, water ingress towards the upstream portion of the Main Railway Tunnel for a considerable 100 meter stretch from the tunnel audit T- junction due to weathered strata also observed.
- The geological research available on the site revealed few faults and discontinuities existing in the area.
- The water ingress is visible at the crown part of the tunnel through the tunnel linings. The continuous and massive water inflow causes high risk for the tunnel lining.
Challenges
- Challenging geology having discontinuities and fault.
- Continuous water inflow ready to flood the tunnel.
- Grouting execution under heavy water inflow.
The 1.4 km T-12 audit tunnel in Imphal faced severe water ingress and structural risks due to saturated media, faults, and discontinuities in the rock mass. Continuous inflow from multiple zones, including the crown, posed a high risk to tunnel lining integrity. Advanced grouting techniques, water control measures, and precision engineering were deployed under constrained conditions to stabilize the tunnel and ensure safe progress in one of India’s most challenging terrains.
