By Lynda Myer
Being located on the Alaknanda River, a major tributary of the Ganga River, in the state of Uttarakhand, almost 500km north-east of Delhi, India’s Vishnugad-Pipalkoti Hydropower Project is under construction.
Building of dams, head race, tail race, diversion and spillway tunnels, vertical shafts as well as a powerhouse with a generating capacity of 444MW, is up to the main contractor, Hindustan Construction Co Ltd.
While the Terratec hard rock double shield TBM with 9.86m diameter is constructing the 13km low-press head race tunnel, Terratec has also supplied a continuously advancing tunnel conveyor for the project.
The path of the Vishnugad-Pipalkoti Hydropower project covers by Dolomitic limestone (33%) and slates (64%), with the remaining 3% passing through critical geological sections, which include thrust zones, with shallow overburden of 150m; five shear zones; and three fault zones.
In order to helping the TBM to dig through the expected hard rock, delivering a torque of over 22,000kNm, the 4,200kW electric main drive is designed, whereas the TBM cutterhead features 19in disc cutters and 12 large bucket openings. During advancement of the TBM, universal reinforced concrete lining rings, measuring 1,500mm wide and 350mm thick, will be installed and the lining rings consist of five segments plus a key.
Additionally, a high-speed regripping system, single-shield advancing mode, high-pressure emergency thrust, and flood control doors, are the contents of this TBM. The location of manufacturing key components of the TBM were Australia and Japan, while the assembly took place at Terratec’s facilities in China.
