Context:
Recently, the collapse of the under-construction Silkyara-Barkot tunnel in Uttarakhand has highlighted concerns about tunnel construction safety. The incident emphasizes the need for a thorough investigation into potential causes and the implementation of preventive measures.
Relevance:
GS III: Infrastructure
Dimensions of the Article:
- Potential Causes of the Silkyara-Barkot Tunnel Collapse
- Critical Aspects of Tunnel Construction
- Major Tunnels in India
- Way Forward for Tunnel Construction and Maintenance
Potential Causes of the Silkyara-Barkot Tunnel Collapse
Background of Silkyara-Barkot Tunnel
Project Overview:
- Part of the Char Dham all-weather road project by the Central Government.
- Constructed by Navayuga Engineering Company, awarded by NHIDCL.
Potential Causes of Tunnel Collapse
Uncertain Cause:
- The exact reason is yet to be determined.
- A possible factor could be a hidden loose patch of fractured or weak rock in the collapsed section.
- Located approximately 200-300 meters from the tunnel mouth.
Probable Scenario:
- Concealed weak rock might have been undetectable during construction.
- Water seepage through the compromised rock could have eroded it over time, creating an unseen void above the tunnel structure.
Critical Aspects of Tunnel Construction
Tunnel Excavation Techniques
Drill and Blast Method (DBM):
- Involves drilling holes into rock and detonating explosives for fragmentation.
- Common in challenging terrains like the Himalayas.
Tunnel-Boring Machines (TBMs):
- Bore through rock while supporting the tunnel with precast concrete segments.
- Expensive but safer method, suitable for rock covers up to 400 meters.
Aspects in Tunnel Construction
Rock Investigation:
- Comprehensive examination of rock strength and composition through seismic waves and petrographic analysis.
- Assesses load-bearing capacity and stability.
Monitoring and Support:
- Continuous monitoring using stress and deformation meters.
- Support mechanisms include shotcrete, rock bolts, steel ribs, and tunnel pipe umbrellas.
Geologist Assessments:
- Independent geologists crucial for examining the tunnel, predicting failures, and assessing rock stability.
Major Tunnels in India
Atal Tunnel (Rohtang Tunnel)
Location:
- Built under the Rohtang Pass in the eastern Pir Panjal range of the Himalayas.
- Situated on the Leh-Manali Highway in Himachal Pradesh.
Key Features:
- Length: 9.02 km.
- World’s longest tunnel above 10,000 feet (3,048 m).
Pir Panjal Railway Tunnel
Location:
- India’s longest transportation railway tunnel.
- Runs through the Pir Panjal mountain range between Quazigund and Baramulla.
Key Features:
- Length: 11.2 km.
Jawahar Tunnel (Banihal Tunnel)
Location:
- Also known as Banihal Tunnel.
- Connects Srinagar and Jammu, facilitating round-the-year road connectivity.
Key Features:
- Length: 2.85 km.
Dr Syama Prasad Mookerjee Road Tunnel (Chenani-Nashri Tunnel)
Location:
- Previously known as Chenani-Nashri Tunnel.
- Longest road tunnel in India.
Key Features:
- Length: 9.3 km.
Way Forward for Tunnel Construction and Maintenance
Stringent Maintenance Schedule:
- Implement regular inspections for structural integrity, drainage systems, and ventilation.
- Promptly address and rectify identified issues.
Advanced Monitoring Technologies:
- Employ sensors and monitoring technologies for continuous assessment of structural health.
- Early detection of potential weaknesses or anomalies.
Periodic Third-Party Risk Assessments:
- Conduct risk assessments considering geological, environmental, and usage factors.
- Periodic evaluations by independent experts.
Contingency Planning:
- Develop contingency plans and emergency protocols for addressing structural concerns.
- Ensure preparedness for unforeseen events.
Personnel Training:
- Train personnel in tunnel management and emergency response procedures.
- Public awareness campaigns to educate users and residents about safety measures and reporting mechanisms.
Incorporate Innovative Technologies:
- Explore the use of Artificial Intelligence, drones, or robotics for efficient inspections and maintenance.
- Embrace technology for early detection of potential issues.
-Source: The Hindu
