TBM RECORDER Double shield taking on tough work in Turkey Aug 2012
Desiree Willis, Technical Writer, The Robbins Company
- In the mountainous terrain of central Turkey, a Robbins hard rock heavyweight is working through demanding conditions. The 10m diameter double shield set off in Spring 2012 following its OFTA (Onsite First Time Assembly) to excavate the 11.8km long headrace tunnel for the Kargi Kizilirmak hydro project, one of the country's largest to date. Dedicated crews working for the contractor Gülermak of Turkey, the project owner Statkraft AS of Norway, and for Robbins, are guiding the machine through changeable geology including mixed weak ophiolite with high clay content and water inflows.
Robbins double shield ready for tough drive in Turkey
- The massive hydroelectric project is in the mountains, near the town of Osmancik, in ground that is expected to comprise volcanic-based rock with softer limestone for the first 3km and giving way to harder rock including marble for the rest of the route. A segmental lining it to be installed through the first 3km with the remainder of the tunnel supported with ring beams, rock bolts, and a final lining of shotcrete.
- A highly adaptable machine has been design, with the ability to install everything from segments to conventional ground support. Both the TBM and backup have required adequate space to accommodate shotcreting, rock drilling and segment handling equipment.
- As of August 2012, the TBM had advanced more than 400m despite extreme ground conditions including unexpected fault zones and inflows of water and mud.
- More than 150 people are employed at the site, with Robbins field staff and Gülermak personnel working together to overcome the conditions. "We have had some very impressive efforts by the Gülermak and Robbins teams," said Glen Maynard, Robbins Field Service Site Manager.
A Robbins continuous conveyor brings up the rear
- After boring the first 175m with a temporary conveyor system, tunneling was interrupted to install the permanent muck haulage conveyor. Gülermak completed this installation in six days and on day seven normal boring operations resumed with the Robbins continuous conveyor system in operation. Maynard added that early TBM advance rates were promising, with day shifts topping 15m and 20m becoming a regular occurrence.
- The Kargi Kizilirmak hydroelectric project, located in Corum Province about three hours from Ankara, will source water from the Kizilirmak River to generate up to 470 GWh annually. The project, for Norwegian company Statkraft AS, is scheduled to go online by the end of 2013.
Dynamic Robbins TBM will adapt mid-bore - TunnelTalk, February 2009
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