TURKEY - BAHÇE-NURDAĞI RAIL | PROJECT
Turkey’s Bahçe-Nurdai rail project has been under development over the last few years with shield tunneling through abrasive hard rock. The Turkish State Railways Directorate (TCDD) has
been building the twin rail tunnel project to help develop the economy in the region. That part of south east Turkey is one of the country’s busiest railway corridors and TCDD plans to overhaul the railway connection by providing a shorter, faster route between the towns of Bahçe and Nurdağı. Earlier this year, though, the region suffered two
consecutive major devastating earthquakes, with magnitudes of 7.8 and 7.6. The Bahçe-Nurdaği rail tunnel project site is located and close to the intersection of two large active fault zones – the East Anatolian Fault (EAF) and Dead Sea Fault (DSF). The tunnels were inspected after the events and they were found to have sustained only minor cracking in a few concrete segments of the bored tunnels, which were nearing completion. The geology in the project area has some of the most
extreme hardness and abrasiveness ever measured in Turkey. It includes incredibly hard and abrasive metasandstone with quartz, with an average of 220 MPa (31,900 psi) UCS and a Cerchar abrasion value of 3.87, says Robbins, which provided a 26.25ft-diameter (8m) single shield to construct the tunnels. The TBM completed the first tunnel in 2020. In June
this year, the TBM completed its second tunnel on the Bahçe-Nurdaği project. A total of 11.6 miles (18.6km) of TBM tunneling was completed. For the two drives, the machine completed drives of
slightly different lengths on the tunnelling challenge. After its first bore in the difficult ground, the machine
required some inspection and repairs. “Robbins Field Service was always available when we
requested,” said Deniz Şahin, TBM Chief for contractor İntekar Yapı Turizm Elektrik İnşaat San. ve Tic. Ltd. Şti. “The biggest repairs we undertook with Robbins Field Service technicians were the main bearing seal change and checking and repairing of the TBM before launching it on the twin tunnel after the completion of the first tunnel. Both operations were completed in a short time due to good planning with Robbins technicians.” The machine began its second bore for the project in
February 2021. “During tunneling we performed a normal
maintenance program as given in the TBM manual, and the machine had minimum downtime, which shows the durability of Robbins TBM in very hard and abrasive rock,” said Şahin. Geology experienced on the second tunnel drive was
comparable to the first, says Robbins, achieving a best monthly advance rate of 450yd (411m). “We are very proud to complete this tunnel in difficult
rock formations with our excellent team,” utilizing the powerful Robbins single shield, said Şahin. Yunus Alpagut, Robbins representative in Turkey, said: the
TBM “has performed extremely well in this project with minimal downtime and good advance rates to complete the longest twin tube railway tunnels in Turkey.”
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Above:
The single shield was designed for hard and abrasive geology, including metasandstone with quartz
Left:
The TBM’s first drive on the rail project was 9.2km long, completed in 2020
Below:
Robbins 8.0m-diameter single shield TBM finished a 9.6km-long drive in June for its second tunnel bore on Turkey’s Bahçe-Nurdai railway project.
ALL IMAGES: COURTESY OF ROBBINS
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