Source – https://www.financialexpress.com/business/railways-kashmir-rail-link-project-indian-railways-develops-new-tunnelling-method-to-conquer-challenging-himalayan-terrain-3284997/
Publisher – Financial Express
Faced with the challenging Himalayan terrain, Indian Railways engineers have devised an innovative tunnelling method to overcome the construction obstacles in Tunnel-1, a crucial component of the 111-km-long Katra-Banihal section of the Kashmir rail link project.
This 3.2-km-long single tube tunnel, situated at the base of the Trikuta Hills in the Katra-Reasi section of the Udhampur-Srinagar-Baramulla Rail Link Project, is considered one of the most formidable sections of the entire project.
“We have innovatively developed (I)-TM as Himalayan tunnelling method for tunnelling through the Himalayan geology to build tunnels in Jammu and Kashmir,” Railway Minister Ashwini Vaishnaw had said recently.
Why develop a new tunnelling method?
A senior railway engineer explained that this approach involved implementing pre-excavation support measures to handle the “flowing conditions” encountered during tunnel excavation. The realignment of the rail line ensured that only a small portion passed through this challenging terrain, which engineers described as the most difficult tunneling conditions faced in the country.
“We inserted nine-metre pipes in the mountains. It is called pipe roofing. We made an umbrella using these perforated poles and filled them with PU grout. It is a chemical that mixes with the soil and increases its volume three times over and solidifies the soil like a rock. This structure is tested for stability and then we proceed with the excavation bit by bit,” the engineer said.
Katra-Banihal section features
Additional features, including stress release holes and wing drainage holes, were also designed to alleviate geological stress. Although work on this critical tunnel was delayed for over three years starting in 2017, engineers now anticipate its completion by early next year.
The Katra-Banihal section covers a total of 111 km, with 27 main tunnels (97 km) and eight escape tunnels (67 km). Additionally, the section comprises 37 bridges, including 26 major and 11 minor ones.
