As the blades of the auger machine drilling through the rubble of the collapsed Silkyara tunnel were on Saturday stuck in the debris, experts present at the site considered switching to options that could drag on the rescue of 41 trapped workers by several days — even weeks.
On day 14 of the multi-agency rescue mission, officials shifted focus to two alternatives — manual drilling through the remaining 10- or 12-metre stretch of the rubble or, more likely, drilling down 86 metres from above.
Here’s an expert’s take on vertical drilling:
“When soil and rocks are subjected to a tremendous amount of pressure, also called geo stress when we try to make a tunnel and this disturbs the equilibrium. Some rocks adapt well and some do not. Rocks at Uttarkashi tunnel have not been adapted well,” Assistant Professor Vivek Padmanabha, Civil Engineering IIT Guwahati said.
“There could possibly be three issues like lack of knowledge of geology, improper design and faulty construction. The third one is the lack of excavation and remediation plans,” he said.
“Vertical drilling is a process in which we drill boreholes down the earth’s surface creating earth shafts. This is for providing direct access to ventilation and communication. If the borehole is wide enough then we can evacuate the trapped persons. The most important thing is geo stress are different at different level so vertical stress will have maximum pressure,” the professor said.
“The casing will prevent rocks from falling in the bore well,” he added.
The rescue effort began November 12 when a portion of the under-construction tunnel on Uttarakhand’s Char Dham route collapsed following a landslide, trapping the workers inside. Rescuers are now exploring other options such as drilling the remaining stretch of 10 to 12 metres manually or creating a vertical escape passage for the 41 labourers trapped inside.
At the disaster site, international tunnelling expert Arnold Dix repeated his promise of getting the workers out “by Christmas”, which is a month away.
Ananya Das is your guide to the latest trends, viral sensations, and internet phenomena. Based on a keen understanding of digital culture, Sophie navigates the ever-evolving landscape of trending topics. With an insightful and engaging approach, she explores what’s buzzing across social media platforms, ensuring readers stay in the loop with the most talked-about and shareable content online.
