TERRATEC announced that its EPB TBM, designated as S42, holed through on Dec. 4, 2015, in Istanbul after completing the first half of its run from Yenimahalle to Veysel Karani for a total of 2,900 m (1.8 miles). The drive was completed in seven months of boring time, with the best day boring 23 rings (34.5 m or 113 ft) and the best month 532 m (1,745 ft).
“S42 has performed without fault in the mixed ground conditions that are typical for this area in Istanbul, from full face of rock to full face of soil and everything in between she has just been flying,” said Sinan Acun, the tunnel chief for the joint venture.
The ground has varied from true mixed ground to soft ground with up to 4 bar EPB face pressure being applied. The machine will be dragged through approximately 200 m (650 ft) of station and then removed via a 60 m (200 ft) deep shaft and relocated to the beginning of the Yenimahalle station and rerun the alignment to complete the section.
Click here for a video of the TBM breakthrough.