Silkyara tunnel collapse: What is rat-hole mining, how is it different from vertical drilling?

Amid these efforts, rat-hole mining, a manual drilling technique, was used, deemed perilous due to its associated risks. Concurrently, vertical drilling attempts were ongoing, while horizontal drilling proved ineffective.

Team Asianet Newsable

First Published Nov 28, 2023, 12:03 PM IST

On the 17th day following the Uttarakhand tunnel collapse, the rescue efforts for the 41 trapped workers were in their final stages. Various methods have been employed by authorities to extricate the workers from the collapsed tunnel.

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As the rescue operation progresses, understanding the drilling methods used becomes crucial.

Rat-hole mining:

Rat-hole mining involves manual drilling, typical in places like Meghalaya. Skilled workers excavate narrow pits, entering them using ropes and bamboo ladders. Despite being hazardous, this method is often employed for coal extraction, though banned in many regions due to fatal accidents related to lack of oxygen.

Neeraj Khairwal, Uttarakhand government’s nodal officer, clarified that the workers involved weren't rat-hole miners but proficient in this technique.

Vertical drilling:

Vertical drilling, executed with machinery, entails boring straight into the ground. In this incident, an 800-mm pipe inserted via vertical drilling aimed to retrieve the trapped workers. Subsequent manual procedures will clear the remaining soil and debris.

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Auger mining:

Auger mining, involving horizontal drilling, uses specialized tools for tunneling without surface disruption. While effective for laying pipes and creating tunnels, it proved less practical in this rescue.

Significant progress in the Uttarakhand rescue operation was marked by the completion of over 51 meters of vertical drilling, leaving approximately 56 meters to dig. The impending airlifting of the workers using buckets is anticipated after this final phase.

Last Updated Nov 28, 2023, 12:03 PM IST