Headrace tunnel Parbati II
Underground Mining Power station construction
Headrace tunnel for Parbati II power plant
National Hydro Power Corp. (NHPC) commissioned JÄGER in 2009 with the planning, coordination and supervision of reactivation of the tunnel boring work to section 4 of the Parbati II headrace tunnel which came to a halt in 2006 due to a cave-in. At station 4,057, the entire TBM installation was submerged by an influx of water (117 l/s maximum) and buried under approx. 7,500 m3 of fine sand. According to a feasibility study conducted by Jäger Bau, the JARVA TBM with a diameter of 6.8 m was modified in the light of the practical construction requirements, making it possible to resume the tunnel boring work on 21.6.2010 after comprehensive operations to stabilise the mountain. The tunnelling ran into further disruption, and extensive injection work was required to overcome it. Jäger Bau took on the role as a NHPC consultant and training supervisory body (supervision) for the local tunnelling teams. The 9,050 m long headrace tunnel crossed through a very tectonically active mountain massif at the foot of the Himalayas. Stratifications of up to 2,000 m in thickness made themselves felt through massive rock burst phenomena, making the tunnelling and securing work all the more difficult.