Uttarkashi tunnel collapse | Drilling snags hold up rescue operation in Silkyara tunnel

Rescue teams spend November 24 fixing snags in the drilling machine, strengthening its platform, and using radar to scan the debris ahead in Silkyara tunnel; mock rescue drill conducted by NDRF

There are only 10 metres of debris left between rescuers drilling in from the Silkyara end and the trapped workers, but officials say it is difficult to anticipate when this last leg of the operation will be completed. | Photo Credit: Shashi Shekhar Kashyap

Rescue teams were not able to move even an inch closer to the 41 workers trapped in the collapsed Silkyara tunnel by November 24 evening, as the entire day was taken up in fixing snags in the drilling machine and using radar to scan the debris ahead for any further obstacles. There are only 10 metres of debris left between rescuers drilling in from the Silkyara end and the trapped workers, but officials say it is difficult to anticipate when this last leg of the operation will be completed.

Some progress has been made on alternative rescue efforts by boring vertically into the tunnel, as well as drilling efforts being made from the other Barkot end.

First visuals of trapped workers 

Chief Minister Pushkar Singh Dhami visited the tunnel site on November 24 afternoon and also briefed Prime Minister Narendra Modi about the rescue operation, which is now in its 13th day.

Strengthening auger platform

The basic plan is to bore a hole in the debris and push in wide pipes which are welded together, through which the workers can be brought back out. A senior official involved in the Silkyara-end operation recapped the progress so far: the auger drilling machine started work in the early hours of November 22 but had to stop that evening as it struck an iron lattice girder, one of the structural elements of the tunnel. Gas cutters removed this hurdle overnight.

On November 22, the machine pushed a ninth pipe in for just 1.8 metres, before vibrations were noticed and drilling was halted again at the 48-metre mark. Late on November 23 night, it was found that a bent part of the forepole from the tunnel lining was stuck in the auger assembly, leading to the vibrations. The teams then worked to strengthen the auger machine’s platform using an accelerating agent for the rapid hardening of concrete.

Hopes and despair as rescue efforts continue at Uttarkashi | In pictures

An under construction tunnel collapsed in the district of Uttarkashi on November 20, 2023, trapping 41 workers inside. In an effort to bring the trapped labourers, many methods are being employed.

Workers work inside the tunnel after a portion of the tunnel collapsed. The tunnel is being constructed under the National Highways and Infrastructure Development Corporation Limited (NHIDCL), on November 19, 2023.

A high-performance drilling machine is being brought for the rescue operation. In total, five different approaches to the workers are being explored simultaneously, on top of the auger machine at the southern entrance. Heavy machinery and concrete blocks were being trucked into the site throughout the day, on November 19, 2023.

New machines near the tunnel. The first machine of Satluj Jal Vidyut Nigam (SJVN) for the construction of the vertical rescue tunnel has already reached the site and operations are being commenced post completion of access road by the Border Roads Organisation (BRO). Movement of two other machines for the vertical tunnel construction started from Gujarat and Odisha by road, on November 20, 2023.

Workers clean extra food bottles that are brought back from the tunnel under rescue operation. The workers are safe and have asked for food, which is being sent to them, the Silkyara police control room said, adding that communication has been established on walkie-talkies. Food packets have been supplied with the help of compressors, it said, on November 20, 2023.

Pipes, machines and slabs are being brought for the rescue operation. In a first major breakthrough in nine days, agencies working round the clock to rescue the 41 workers trapped in an under-construction tunnel at Silkyara in Uttarkashi district of Uttarakhand have managed to install a six-inch pipe into the 53-metre-long debris on November 20, 2023.

Prayers are being offered by different pandits next to the tunnel. The government is sending multivitamins, antidepressants and dry fruits to 41 workers trapped for the past seven days in an under-construction tunnel that collapsed in the Uttarkashi district of Uttarakhand, Road, Transport and Highways Secretary Anurag Jain said, on November 20, 2023.

Arnold Dix, President , International Tunnelling and Underground Space Association, from Australia, inspects the vertical drilling on top of the mountain face below which the under construction tunnel collapsed, on November 20, 2023.

Wife (Rajni) of a trapped worker (Birender Kisku) from Banka, Bihar, gestures near a temporary police help desk near the Uttarkashi Tunnel Collapse site. 41 workers have been trapped since Nov. 12 morning at the partially collapsed Silkyara tunnel.

Workers stand on top of the mountain face below which the under construction tunnel collapsed, on November 20, 2023.

Workers make road for the vertical drilling on top of the mountain face. Rescue workers at the collapsed tunnel in Uttarkashi started exploring other ways to reach workers, including from the top of the mountain face through which the tunnel is being constructed, officials announced on Saturday. The longer 170 metre route from the top, running simultaneously with other approaches, may take far longer to bore through than the approximately 60 metres of rubble at the southern entrance, on November 18, 2023.

NDRF at the spot from where vertical drilling will start on the mountain face. About 160 personnel of agencies such as the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF), Indo-Tibetan Border Police (ITBP) and the Border Roads Organisation (BRO) are trying to rescue the trapped labourers, on November 17, 2023.

A help desk has been installed near the tunnel collapse site, to help the families of the workers trapped inside the under-construction tunnel, on November 19, 2023.

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“By November 24 morning, the platform for the auger machine was strengthened by way of anchoring, bolting, concreting foundation, etc. But work couldn’t resume as the auger was needed to further pull back fully to assess any other damage to the pipe,” the official said.

Radar shows no obstacles

The rescue teams also used ground penetration radar to scan for any further obstacles lying ahead, said senior Uttarakhand government official Bhasker Khulbe, a former advisor to the PM, adding that the scan showed that there are no major hurdles like rocks or iron objects in the next five metres of debris.

By 2:30 p.m., augur re-assembly work was completed and the machine was reinserted in the pipes to push them further. However, before the placing and positioning of the next pipe, the auger again developed a snag. Till 9 p.m., drilling had not restarted.

He never told us his work was dangerous: Brother of trapped Uttarkashi tunnel victim

Rescue drills and preparation

On November 24, the trapped workers were given roti, dal, mixed vegetables and fruits, as well as medicines, all pushed through a narrower pipe of just 150 mm diameter. A modified wire communication system was used to talk to the workers and give them a medical consultation.

In a mock rescue drill at the site, a jawan from the National Disaster Relief Force was sent inside the escape passage, pushing a wheeled stretcher tied to a rope and was later pulled back. He informed the rescue teams of the oxygen status inside the tunnel.

Forty-one ambulances are stationed outside the tunnel to rush workers after evacuation to the Chinyalisaur community health centre, where a separate ward has been set up with 41 oxygen-supported beds for them.

Alternative rescue routes

While there was no progress in horizontal drilling, a drilling point has been finalised for the vertical drilling efforts at Silkyara, and the drilling machine has been assembled. This vertical drilling is expected to be completed by November 26.

At the Barkot end, the horizontal drilling managed to make a drift of 9.10 metres after four blasts. Shotcreting and rib erection has been completed and additional rib fabrication work is in progress at this site. The platform for perpendicular-horizontal drilling was completed on Friday, and equipments will be set up for further work on Saturday morning.

On November 12, a collapse occurred in the under-construction tunnel from Silkyara to Barkot, with debris falling in a 60-metre stretch on the Silkyara side. The workers are trapped within a space measuring 8.5 metres in height and two kilometres in length which lies in the built-up portion of the tunnel, meaning that they have access to electricity and water supply.