Indian Railways, in its ambitious venture to connect the picturesque lands of Jammu and Kashmir, has encountered an engineering challenge like no other. Nestled within the daunting Himalayan terrain, the Katra-Banihal section of the Udhampur-Srinagar-Baramulla Rail Link Project posed an obstacle that demanded an innovative solution.
The Herculean Tunnel-1: A Formidable Feat
At the heart of this challenge lay Tunnel-1, a 3.2-kilometer-long single tube tunnel situated at the base of the Trikuta Hills. This tunnel, forming a part of the 111-kilometre-long Katra-Banihal section, was considered one of the most formidable segments of the entire project. The treacherous Himalayan geology presented a formidable obstacle to traditional tunnelling methods.
Introducing (I)-TM: The Himalayan Tunnelling Method
In response to these challenges, Indian Railways engineers devised an innovative tunnelling method known as the Himalayan Tunnelling Method, or (I)-TM. This revolutionary approach aimed to address the unique demands of excavating tunnels within the Himalayan geology. Railway Minister Ashwini Vaishnaw, in a recent announcement, hailed this development as a game-changer for the project.
Pre-excavation Support and The Umbrella Effect
The (I)-TM involved implementing pre-excavation support measures that could manage the “flowing conditions” experienced during tunnel excavation. The most distinctive aspect of this method was the introduction of nine-metre pipes into the mountains, aptly named ‘pipe roofing.’ These perforated poles were utilised to create an umbrella-like structure, which was subsequently filled with Polyurethane (PU) grout. This chemical mixture, upon interacting with the soil, increased its volume threefold and solidified it, forming a robust foundation for the tunnel. This structure was rigorously tested for stability before proceeding with the excavation process, ensuring the safety of the construction.
Stress Release and Geological Alleviation
In addition to the innovative pre-excavation measures, the (I)-TM incorporated stress release holes and wing drainage holes to alleviate geological stress, making it a comprehensive solution for the challenging Himalayan terrain.
Overcoming Delays: The Journey Towards Completion
Despite encountering significant delays during the initial phases of construction that stretched over three years from 2017, engineers are now optimistic about completing Tunnel-1 by early next year. This reflects the remarkable progress made possible by the (I)-TM in conquering the challenging Himalayan terrain.
Katra-Banihal Section’s Impressive Features
The Katra-Banihal section, a jewel in the crown of the Udhampur-Srinagar-Baramulla Rail Link Project, encompasses a total stretch of 111 kilometres. It boasts a network of 27 main tunnels, spanning 97 kilometres, alongside eight escape tunnels covering an additional 67 kilometres. The section is further adorned with a total of 37 bridges, comprising 26 major and 11 minor structures.
(I)-TM marks a revolutionary milestone in the development of Indian Railways, showcasing the remarkable capability of innovation to conquer even the most daunting terrains. As the Katra-Banihal section nears completion, it is evident that this ingenious solution has opened new doors to railway connectivity in the breathtaking landscapes of Jammu and Kashmir.
