Istanbul Metro breakthrough
TURKEY – The TBM mining the 2,900m Yenimahalle to Veysel Karani section of the Istanbul Metro broke through in December. The drive took seven months.
The contractor, a joint venture of Gulermak, Kolin and Kalyon then began the process of dragging the machine through 200m of station to a 60m-deep access shaft to remove the 6.56m-diameter TBM. It will then be returned to Yenimahalle to drive the second tube.
The ground has varied from true mixed ground to soft ground with up to 4 bar face pressure applied. The tunnel is lined with universal reinforced concrete segments with an outer diameter of 6,300mm, inner diameter of 5,700mm and width of 1,400mm.
A spokesman said: "A generous program has been given for completion by February 2017, however if as expected the completion is earlier, S42 might assist the other machines on the project to complete their lots."

29 January 2016
Link: http://www.tunnelsonline.info/news/istanbul-metro-breakthrough-4796420/