India’s longest railway tunnel is currently under construction in Uttarakhand. Dodded Tunnel No. 8 or T -8, it will be a 14.57 km tunnel between the silk and the Karni Parig, and will contact Deepraig and Johnso in Uttarakhand. Although the length of the tunnel itself is an important achievement of engineering, the technology that is digging and construction of this structure in such a challenging region deserves recognition. To make a hole in the mountains, engineers used a German tunnel -boring machine (TBM) and a new tunnel tunnel (NATM) in the German tunnel (TBM) and a German tunnel boring machine (TBM).
TBM Shakti and NATM use to build India’s longest railway tunnel
Larson & Tobro (L&T) announced that it had made progress in the tunnel excavation project in April. The tunnel progress is a point of digging when both ends of the tunnel are finally connected. The tunnel, which is part of the Rail Coasse Nigam Limited (RVNL), is part of the Rishkish-Carnaparag Broad Gage Rail Link Project, is expected to work by the end of 2026.
Once it becomes operational, T-8 will eliminate the 12.75 km long T-49 tunnel between Khairi and Sambar stations at Adhmapur-Sri Nagar Baramola Rail link in Jammu and Kashmir.
At the time, L&T said that 10.4 km of tunnel was completed using Shakti’s single shield TBM. With 9.11m Qatar, it is said that it is the largest TBM to deploy in the Himalayan region. He excavated an average of 413 meters every month. The remaining 4.11 km tunnel was completed using NATM.
A TBM is a huge cylindrical machine that is capable of digging tunnels through both clay and rock, while the surrounding ground causes minimal disruption. It has a steel disk rotating with a disk cutter that cuts off with rocks on high pressure. The cutter is designed to cut through headquarters, skirts and phlevites, which are common in Himalayan rock deposits.
A segment erector system is behind the cutter head, which increases the cost concrete classes to add structural integrity to the freshly excavated tunnel. In addition, the debris (also known as the makk) is permanently removed from the tunnel using the conveyor system.
Although TBM was used for large parts of the tunnel, it cannot be used in difficult geological areas that agree with the fault zone, entering the water and more. The use of a large machine for digging these parts can negatively affect the structural integrity of the entire tunnel.
L&T says it used NATM, which uses drill and blast or mechanical excavation techniques with permanent monitoring of the ground condition. Generally, small parts are excavated at a time using this technology. Once the rock and the munk are removed, the shot crate (sprayed concrete), rock bolts, and steel ribs are added to the exposed area to avoid malfunction and fall.
Throughout the process, the staff monitors the tension and movement of the tunnel using equipment such as the extensometer and load cells. NATM is important for digging in challenging regions, as they reduce dependence on large machinery and flexibility in the construction process.
