After setback in Uttarkashi tunnel rescue, bigger machine flown in from Delhi

The auger is a rotating drill bit or tool that is helical in shape and is used to create holes or excavate material by removing it from the drilling surface. The rescue plan remains the same – using the “trenchless” technique and creating a passage with 900 mm wide mild steel pipes that the workers can crawl through.

In the first two days, the plan was to remove debris using heavy excavator machines, and prevent more debris from falling using the “shotcrete method” – as soon as debris is removed, concrete is shot at high pressure to prevent more from falling. This was only partially successful.

The rescuers opted for a different approach – of using the auger drilling machine – on Tuesday night. About two metres of pipe was also inserted into the debris through the machine. However, the machine, provided by Vardhman Engineering Works, was not able to cut through the debris at a high enough speed. A decision was then taken to remove that machine and bring a bigger one.

“After the previous plans failed, we have switched to the next plan. We are first installing an additional 125 mm pipe for air, food, camera, and communication. That pipe is already 12 metres in. Also, a state-of-the-art, American-made horizontal dry drilling equipment with auger has arrived from Delhi on two Hercules C-130 planes,” Bhupendra Singh, DGM, Rail Vikas Nigam Limited (RVNL) informed The Indian Express. The RVNL has now been given the responsibility to carry out the drilling operation.

“We are almost certain this plan will work. If not, the final option will be using conventional drilling using the pipe roof umbrella method. Under that, we will build an entire tunnel and it will take five to six days as it goes just around 10 meters a day. However, we are sure it will not come to that and the second plan will work,” he said.

The pipe roof umbrella method is a technique used in tunnel construction, particularly in soft or loose ground conditions where there is a risk of tunnel collapse during excavation. This method involves the use of pipes or tubes to create a protective umbrella-like structure within the tunnel’s excavation face to support and stabilise it.

Adesh Jain, owner of Vardhman Engineering Works, told The Indian Express that his machine is 35 HP (horsepower) and weighs 9 tonnes, while the new machine is around 175 HP and considerably heavier at 25 tonnes. The platform to support both machines is also different. Through the new machine, 5 meters of debris can be removed per hour. The workers were initially trapped behind roughly 50-55 metres of debris, some of which has been removed.

“For the last three days we have been continuously trying to get the workers out. But the rock here is very fragile. Whatever we dig, more debris falls. Therefore, we are focusing on inserting the mild steel pipes. The latest machine has arrived here. We are already two-three metres inside, and the rate of penetration of the new machine is much higher at around four-five metres in just one hour. Tentatively, it will take 10-12 hours for 50 metres,” said Anshu Manish Khalkho, director NHIDCL, adding that if this plan does not work, they have more back-up plans ready.

In a statement, the state government said that the help of special teams from Norway and Thailand is also being taken. “The rescue team has contacted the Thailand company which had rescued the children trapped in the cave there. Norway’s NGI agency has also been contacted to obtain specific suggestions for operations inside the tunnel. Suggestions related to operations inside the tunnel are also being taken from experts of Indian Railways, RVNL, Rail India Technical and Economic Service and Indian Railway Construction International Limited,” said the state government.

Meanwhile, tunnel workers and locals gathered at the site on Wednesday morning and protested against the administration and the construction company, accusing them of not doing enough to rescue the men. “The construction firm officials are not talking to us properly, nor is there any information on what is happening inside. Those inside are our brothers,” said Luv Kumar Raturi, a construction worker.