HCC has made history by successfully completing the first tunnel constructed using Tunnel Boring Machine (TBM) in Himalayan Terrain for its Kishanganga Hydroelectric Power Project in Jammu and Kashmir. The tunnel boring machine emerged out successfully on Monday, June 10 2014, completing the 14.75 km tunnel. With this, HCC has completed tunneling work of the project well ahead of schedule.
The 330 MW Kishanganga Hydroelectric Power Project is located on River Kishanganga, a tributary of river Jhelum, in Bandipore district of Jammu & Kashmir. HCC, in a joint venture with Halcrow Group Ltd. U.K. (Halcrow) is executing the project for the National Hydroelectric Power Corporation Ltd. (NHPC). The project is run of the river scheme and involves transfer of water of Kishanganga River in Gurez valley to Bonar nallah near Bandipore in Kashmir valley.
Kishanganga Hydroelectric Power project is being constructed by HCC on EPC basis. The project has a 23.65 km long Head Race Tunnel to carry the water from dam to the powerhouse. The tunnel is constructed using two methodologies - 14.75 km tunnel is constructed by Tunnel Boring Machine and the remaining 8.9 km tunnel is constructed by conventional drill and blast method. This is one of the Longest HRT in India with maximum overburden (height of mountain above tunnel) of 1470 m.
Speaking on the occasion, A.I. Benny, Project Manager HCC said, "Using tunnel boring machine in young Himalayan Mountains poses various geological and technical challenges. We are indeed proud of having a capable team that took up this challenge and with meticulous planning and precise execution overcome all hurdles to complete the tunnel well ahead of time."
A state-of-the-art Double Shield TBM was ordered from SELI of Italy for this specialized job. The 225 meters long TBM with a cutter head of 6.18 meters was transported to the project location via Mumbai in 160 container shipment. Transporting the machine to project location in Jammu & Kashmir was a major logistical challenge which was completed in three months. The TBM commenced its first drive on April 20, 2011 and completed the tunnel today with average monthly progress of around 500 meters. In November 2012, HCC made a national record of highest monthly tunneling progress of 816 meters at Kishanganga project.
Government, of India has cleared the Project from the Indus Waters Treaty. The contract is on a turnkey basis valued at approximately Rs 2726.49 crore.
Project's Major components:
- Dam - 37 m high Concrete Face Rock fill Dam (CFRD)
- Diversion Tunnel - 9.5m diameter, 560 m long Diversion tunnel
- Head Race Tunnel - 23.65 km long Head Race Tunnel to carry the water from dam to the powerhouse - one of the Longest HRT in India with overburden (height of mountain above tunnel) of 1470 m.
- The construction of Head Race Tunnel is carried out using two methodologies. The 8.9 km tunnel of 6 m diameter from the dam side is constructed using the conventional Drill and Blast Method while the balance 14.75 km with a finished diameter of 5.2 m from the powerhouse side is constructed using Tunnel Boring Machine
- Tail Race Tunnel- Tail Race system discharges water back into the stream after power generation and comprises of 862 m long and 5 m diameter D-shaped tunnel and a 44 m long open channel.
- Surge Shaft - It is a part of the water conductor system to power house located at the end of the Head Race Tunnel which acts as a balancer to absorb the effect of water hammer when the water in motion is forced to stop. The Surge Shaft at Kishanganga is a vertical shaft of 18.75 m diameters and 100.7 m deep.
- Pressure Shaft - One steel lined pressure shaft 4.0 m diameter trifurcating at the bottom into three penstocks 2.1 m diameter each to create pressure in turbines for power generation.
- Power House - The underground Power Station consisting of two parallel caverns, one for the three generating units and the other for transformer.
- Switchyard - A surface Switchyard