Robbins has supplied a 10 m diameter Double Shield tunnel boring machine (TBM) to the Kargi Kizilirmak Hydroelectric Project in the mountainous region of central Turkey. The TBM was launched earlier in the year and has currently completed 400 m of tunnels through the challenging and changeable geology of the site.
The 102 MW scheme will be one of Turkey's largest and is designed to exploit a 75 m elevation change in the Kizilirmak, Turkey's longest river. The scheme involves construction of a 13 m high, 500 m wide dam and a 11.8 km long headrace tunnel through a mountain near the town of Osmancık. The main contractor for the scheme is Gülermak, while the project owner is Norway's Statkraft.
The geology for the tunnel route - 3 km of volcanic rock with softer limestone, which will then give way to softer rock, including marble, means the lining of the tunnel will change. The first 3 km will feature a full segmental lining, but after that ring beams, rock bolts and shotcrete will be used. This has meant a unique design was required for the TBM, to allow give enough space for the different types of support to be installed.
The scheme is expected to generate 470 GWh of electricity per year - enough for 150,000 homes, and is scheduled for completion by the end of 2013.