Rescue Operations at Silkyara Tunnel Collapse Site on War Footing Mode

Newdelhi:25/11/23:Continuing their unwavering commitment to saving lives, the government is actively engaged in ongoing rescue operations at the Silkyara Tunnel in Uttarkashi, where 41 workers remain trapped. The 2 km section of the tunnel, with completed concrete work ensuring the safety of the workers, is the focus of the rescue efforts.

Various government agencies are working tirelessly on each assigned specific task to ensure the safe evacuation of the workers. National and International experts are present at site to advise on the rescue operation. The government maintains constant communication to boost the morale of those trapped.

Key Updates on Rescue Operations:

1.         NHIDCL Lifeline Efforts:

• Freshly cooked food and fresh fruits are being inserted inside the tunnel at regular intervals using the 2^nd life line (150 mm dia.) service.
• Sufficient fruits like orange, Apple, Banana etc., along with medicines and salts has also been supplied in this lifeline in regular interval. Additional Dry Food are also being supplied for future stock.
• Modified communication system with wire connectivity developed by SDRF is being used for communication regularly. People inside have reported that they are safe.

2.      Horizontal Boring by NHIDCL

• Auger drilling started at 0045 Hrs on 22.11.2023 was halted due to metallic object (Lattice girder rib) being encountered in front of the pipe and the pipe could not be inserted further. Cutting of Metallic object (Lattice Girder rib) using Gas cutters has been completed. Pushing of 9^th pipe reached an additional 1.8 meter distance. Minor vibration was noted, so Auger was pushed slightly back to re-assess the force to be applied. Obstructions were observed.
• A bend part of forepole (pipe) from tunnel lining was struck in the auger assembly which led to vibrations.
• Strengthening of platform for auger machine using accelerating agent for rapid hardening of concrete is completed.
• Platform for Auger Machine has been strengthened by way of anchoring, bolting, concreting foundation etc.
• Further, auger was required to pull back fully to assess any other damage to pipe. Auger pulling has been completed. GPR (Ground Penetration Radar)  test has been completed. Welder’s team has gone inside the pipe for cutting of bent pipe. Cutting of bent pipe completed.
• Augur re-assembly work completed and all augurs reinserted by 1430 hrs.
• Pushing of 10^th Pipe( 4.7 m length) started at 1625 hrs on 24.11.2023 and a length of 2.2 m was inserted upto 1750 hrs on 24.11.2023 resulting In total inserted length of 46.9 m.
• During pushing of 10^th pipe, further obstruction was observed and pushing of pipe had to stop. Thereafter, pulling back of auger was initiated. 15 m length of Auger came out initially by pulling and thereafter the auger joints got broken and facing difficulties for pulling of auger in one go due to probable hard stuck of auger.
• Thereafter manual cutting of auger in small pieces by gas cutting and taking out of the same from inside the pipe (800 mm) is adopted. As of now, 22.6 m length of auger out of total 46.9 m has been taken out and the process is going on.

3.   Vertical Drilling for Rescue by SJVNL:

• Drilling Machineries arrived at site.
• Platform for launching of drilling machine has been completed. Marking of drilling point over the tunnel has been finalized at Ch. 300 L/S after discussion with GSI, RVNL & ONGC.
• Assembly of machine started.

4.   Horizontal Drilling from Barkot Side by THDCL:

• THDC has initiated the construction of a rescue tunnel from the Barkot end, with four blasts already completed, resulting in a 9.10 meter drift.
• Shotcreting and rib erection has been completed and additional rib fabrication work is in progress.

5.   Perpendicular-Horizontal Drilling by RVNL:

• Equipments for micro tunneling required for horizontal drilling to rescue labourers has reached site from Nashik and Delhi.
• Platform likely to be completed by 25.11.2023. Equipment to be set up by 27.11.2023.

6.  Vertical Drilling (6 inches) by RVNL at Silkyara end:

• Access road of 1150 meter has been completed by BRO and handed over to RVNL. Machine for drilling towed to location by BRO.
• Electric Connection has been provided to RVNL.

7.   Vertical Drilling Toward Barkot End by ONGC

• ONGC drilling team visited the site on 20.11.2023.
• Air drilling Rig machine from Indore has reached site.
• Submission of report by ONGC to be made after completion of field survey.

8.   Drift Tunnel by Manual-Semi Mechanized Method by Joint Team of THDCL /Army/Coal India and NHIDCL:

• Drift design completed( 1.2m X 1.5m sections)
• Material available at site.
• Fabrication started on 21.11.2023 by Army welders.
• 18 numbers of frames have been fabricated.

9.   Road Cutting and Supportive Work by BRO:

• BRO has completed construction of approach road for vertical drilling by SJVNL and RVNL.
• BRO is also building approach road for ONGC with geological surveys conducted by ONGC. 950 meters of approach road has been constructed so far out of 5000 meters.

Background:

On 12th November 2023, a collapse occurred in the under-construction tunnel from Silkyara to Barkot due to debris falling in a 60-meter stretch on the Silkyara side. Immediate mobilization of resources by the State and Central Governments ensued to rescue the 41 trapped labours.

Initially opting for a 900 mm pipe through the debris, safety concerns led to the exploration of multiple rescue options simultaneously. The area of entrapment, measuring 8.5 meters in height and 2 kilometres in length, is the built-up portion of the tunnel, offering safety to the labours with available electricity and water supply.

Five agencies—ONGC, SJVNL, RVNL, NHIDCL, and THDCL—have been assigned specific responsibilities, working collaboratively with occasional task adjustments for operational efficiency.

Note: The timelines provided are subject to change due to technical glitches, the challenging Himalayan terrain, and unforeseen emergencies.