Dynamic Robbins TBM will Adapt Mid-bore

Feb 19, 2009

An extensive hydroelectric project in northeast Turkey will employ a Robbins Main Beam TBM at two different tunnel diameters. Launched in Winter 2008/2009, the 4.8 m (15.8 ft) diameter TBM and back-up are excavating a series of headrace tunnels for contractor Kolin Construction Co. Inc.

The TBM, for the Akköy II Hydroelectric Project, is utilizing 19 inch cutters to bore a series of three tunnels in sub-volcanic rock, granite, and rhyolite. The initial 6.7 km (4.2 mi) tunnel, at 4.8 m (15.8 ft) diameter, will be followed by two additional tunnels at 4.0 m (13.1 ft) diameter (measuring 4.8 km and 4.0 km in length).

Diameter change will require removal of the outer cutterhead sections, bottom and side supports, roof shield, dust shield, and gripper shoes. The components will then be replaced with 4.0 m (13.1 ft) diameter adaptations before the machine is transported to the smaller tunnel sections.

Differing tunnel diameters were designed into the massive Akköy II hydropower scheme—one of the 4.0 m (13.1 ft) diameter tunnels will transfer water from several sources to the main Gökçebel reservoir, capable of holding over 100 million cubic meters (3 billion cubic feet) of water. The 4.8 m (15.8 ft) diameter tunnel will transfer water from the reservoir to the Yaşmaklı Dam site, a concrete gravity dam 100 m (328 ft) high. From there, water is sent through the second 4.0 m (13.1 ft) diameter tunnel to a surge chamber at the Akköy II power plant located on Harşit River.

Kolin is undertaking the construction works for Akköy Energy A.S., who owns the license for the project according to the Electricity Market Law in Turkey. Once complete, the Akköy II Hydroelectric Project will supply 898 million KWh annually to the National Grid at a 154 kV voltage level. The new project will add to the current 315 million KWh supplied by the Akköy I Hydroelectric Project. The Akköy I project has been completed and is in operation, also generating energy by diverting water from the nearby Harşit River.

The Robbins Company
Brianna Home
29100 Hall Street
Solon, OH 44139
PH.: 253.872.4484
E-Mail: homeb@robbinstbm.com
Internet: www.robbinstbm.com

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