Uttarkashi tunnel collapse: Rescue operations to evacuate 41 workers trapped in Uttarakhand's Silkyara tunnel came to an end for the day with several developments on Saturday. These include landline wires being laid around the area while mobile phones and board games were sent to the trapped workers to help alleviate stress.
Earlier, the auger drilling machine hit a metal girder in the evening, a little after drilling was resumed after officials resolved a technical snag. The 25-tonne machine restarted on Friday evening and drilling resumed. However, a fresh hurdle was faced as the boring continued for about an hour before the drill hit a metal girder.
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 2nd 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 9th 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 10th 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 10th 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.
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