Marmaray (Bosphorus) Tunnel
HEIGHT: maximum ..9.8 m minimum ..8.6 m
WIDTH: maximum ..18.38 m minimum ..16.5 m
TOTAL IMMERSED LENGTH: 1387 m
DEPTH AT BOTTOM OF STRUCTURE: Depth below sea level ..56.1 m max, 37.3 m min
ENVIRONMENTAL CONDITIONS:
No marine work during fish migration seasons. Wreck on alignment removed. Ordnance
recovered during dredging. Initial zone of contaminated material removed with closed clamshell
and placed in sealed landfill. Immersed tunnel wholly within soft material. Contractor selected
TBM interface locations to be start of rock.
FABRICATION METHOD:
Two dry docks, each just fitting two elements within vertical
walls, excavated in Tuzla DLH harbour.
WIDTH: maximum ..18.38 m minimum ..16.5 m
TOTAL IMMERSED LENGTH: 1387 m
DEPTH AT BOTTOM OF STRUCTURE: Depth below sea level ..56.1 m max, 37.3 m min
ENVIRONMENTAL CONDITIONS:
No marine work during fish migration seasons. Wreck on alignment removed. Ordnance
recovered during dredging. Initial zone of contaminated material removed with closed clamshell
and placed in sealed landfill. Immersed tunnel wholly within soft material. Contractor selected
TBM interface locations to be start of rock.
FABRICATION METHOD:
Two dry docks, each just fitting two elements within vertical
walls, excavated in Tuzla DLH harbour.
Istanbul,
Turkey
DLH (General Directorate of Railways Harbours and Airports Construction)
Taisei-Gama-Nurol JV
Taisei-Gama-Nurol JV
2 no. elements @ ..98.5 m 1 no. element @ ..110 m 8 no. elements @ ..135 m
1387m
Depth below sea level ..56.1 m max, 37.3 m min
Project construction
11
1-track per tube
maximum ..9.8 m minimum ..8.6 m
maximum ..18.38 m minimum ..16.5 m
Tunnel ends designed to receive rock TBM in each tube at offshore location. Internal access via
access shaft installed several weeks after immersion, near shallow end of Element 11. Shaft
had weak link and emergency seal in case of ship impact. Roof provided with second location
for rescue shaft. Contractor elected to place concrete in upper half of walls and roof after floatout
within braced steel membrane. Last element placed 11 Oct 2008, last TBM docked 2011
access shaft installed several weeks after immersion, near shallow end of Element 11. Shaft
had weak link and emergency seal in case of ship impact. Roof provided with second location
for rescue shaft. Contractor elected to place concrete in upper half of walls and roof after floatout
within braced steel membrane. Last element placed 11 Oct 2008, last TBM docked 2011
Two dry docks, each just fitting two elements within vertical
walls, excavated in Tuzla DLH harbour.
walls, excavated in Tuzla DLH harbour.
Upper walls and roof cast
afloat at adjacent temporary
floating jetties
afloat at adjacent temporary
floating jetties
No marine work during fish migration seasons. Wreck on alignment removed. Ordnance
recovered during dredging. Initial zone of contaminated material removed with closed clamshell
and placed in sealed landfill. Immersed tunnel wholly within soft material. Contractor selected
TBM interface locations to be start of rock.
recovered during dredging. Initial zone of contaminated material removed with closed clamshell
and placed in sealed landfill. Immersed tunnel wholly within soft material. Contractor selected
TBM interface locations to be start of rock.
Purpose-built rigid catamaran immersion rig with up to 13 anchors used during immersion,
initially parallel to strong surface current; later rotated for placement when element deeper.
initially parallel to strong surface current; later rotated for placement when element deeper.
Gina, omega, all joints made
rigid. Axial seismic joint in
adjacent bored tunnel segments.
rigid. Axial seismic joint in
adjacent bored tunnel segments.
Steel shell on sides and base with anodes, sealed into 10 m2 zones; sheet membrane on roof;
watertight concrete also a requirement.
watertight concrete also a requirement.
Gravel 800 mm thick was roughly levelled 450 mm low by remotely controlled grader robot.
After element placed, remaining space filled with thixotropic grout that does not penetrate
gravel.
Extensive area with close-spaced compaction piles to reduce risk of liquefaction during 7.5
magnitude earthquake expected within 30 years.
After element placed, remaining space filled with thixotropic grout that does not penetrate
gravel.
Extensive area with close-spaced compaction piles to reduce risk of liquefaction during 7.5
magnitude earthquake expected within 30 years.
Rock and gravel to relieve excess pore
water pressure (seismic)
water pressure (seismic)
Grade of concrete, mix
provisions, cooled, prestressed, design code
used.
provisions, cooled, prestressed, design code
used.
temporary condition/permanent condition