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A platform for research: civil engineering, architecture and urbanism
Marmaray (Bosphorus Crossing)
Highlights Deepest immersed tunnel had significant environmental challenges. Temporary access shaft on E11 provided vital access during construction. Hybrid and reinforced concrete with steel membrane adopted. Rigid joint design adopted to cater high seismic force.
Abstract It is possible to construct deeper and longer immersed tunnels when the connection to land, ventilation, emergency evacuation systems, connection details between elements and similar key features are assessed and designed appropriately. Being the deepest and one of the most challenging immersed tunnels constructed to date, the Bosphorus Crossing included various innovative techniques. The Bosphorus Crossing project is located in Istanbul, Turkey, connecting the European and Asian sides of the city. The works included a double-track railway immersed tunnel with a length of 1387 m at a maximum depth of approximately 60 m below sea level. The tunnel consists of a total of 11 tunnel elements 15.3 m wide and 8.6 m high. Elements were constructed as reinforced concrete (RC) with an external steel waterproof membrane and with a transition to sandwich section for the element joint areas. Element no.11 also had a full-sandwich section in the vicinity of the access shaft connection. Design life of the permanent structures is 100 years. Elements were prefabricated in two drydocks approximately 40 km from the immersion site. Due to the expected severe seismic shaking, a sand foundation was unsuitable. A gravel foundation was placed low and roughly levelled using a remotely operated blade. Under-base grouting was injected from inside the tunnel elements to fill all gaps between the gravel foundation and the bottom slab. The tunnel is in a high seismic zone of Magnitude 7.5, which was considered in the design. Towards the Asian end of the tunnel, ground improvement using compaction grouting was used to minimize the risk of soil liquefaction. A total of 1.2 million m3 of seabed was excavated, of which 118,000 m3 was contaminated soil that had to be dumped in a confined disposal facility created on land nearer the Black Sea. The adjacent bored tunnels were constructed using tunnel boring machines (TBMs) that were driven at depth through pre-mixed soil into receiving chambers at the two ends of the immersed tunnel.
Marmaray (Bosphorus Crossing)
Highlights Deepest immersed tunnel had significant environmental challenges. Temporary access shaft on E11 provided vital access during construction. Hybrid and reinforced concrete with steel membrane adopted. Rigid joint design adopted to cater high seismic force.
Abstract It is possible to construct deeper and longer immersed tunnels when the connection to land, ventilation, emergency evacuation systems, connection details between elements and similar key features are assessed and designed appropriately. Being the deepest and one of the most challenging immersed tunnels constructed to date, the Bosphorus Crossing included various innovative techniques. The Bosphorus Crossing project is located in Istanbul, Turkey, connecting the European and Asian sides of the city. The works included a double-track railway immersed tunnel with a length of 1387 m at a maximum depth of approximately 60 m below sea level. The tunnel consists of a total of 11 tunnel elements 15.3 m wide and 8.6 m high. Elements were constructed as reinforced concrete (RC) with an external steel waterproof membrane and with a transition to sandwich section for the element joint areas. Element no.11 also had a full-sandwich section in the vicinity of the access shaft connection. Design life of the permanent structures is 100 years. Elements were prefabricated in two drydocks approximately 40 km from the immersion site. Due to the expected severe seismic shaking, a sand foundation was unsuitable. A gravel foundation was placed low and roughly levelled using a remotely operated blade. Under-base grouting was injected from inside the tunnel elements to fill all gaps between the gravel foundation and the bottom slab. The tunnel is in a high seismic zone of Magnitude 7.5, which was considered in the design. Towards the Asian end of the tunnel, ground improvement using compaction grouting was used to minimize the risk of soil liquefaction. A total of 1.2 million m3 of seabed was excavated, of which 118,000 m3 was contaminated soil that had to be dumped in a confined disposal facility created on land nearer the Black Sea. The adjacent bored tunnels were constructed using tunnel boring machines (TBMs) that were driven at depth through pre-mixed soil into receiving chambers at the two ends of the immersed tunnel.
Marmaray (Bosphorus Crossing)
Ozgur, Ozturk (author) / Ingerslev, Lars Christian (author) / Iversen, Claus (author)
2021-11-20
Article (Journal)
Electronic Resource
English
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