B+S
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Description
A subterranean rail link was constructed for the new Berlin Brandenburg Airport. This includes the 6-track station located directly beneath the airport terminal for S-Bahn, regional, and ICE services, as well as the adjacent 4-track and 2-track line tunnels from the station to outside the airport grounds. The total length of the rail link, consisting of numerous individual structures, is 3,100 m.
The individual structures were erected in several parallel linear construction sites using open-cut construction methods, protected by sheet pile walls. The sheet pile walls were anchored using strand anchors and an anchor wall located at a distance behind the retaining wall. Groundwater lowering was achieved by means of wells outside the excavation pit, which were continuously expanded along with the linear construction sites.
The structures are designed as a watertight concrete structure for a maximum water level (HGW100) of approximately 8.50 m above the lower edge of the base. Due to the alternating layers of boulder clay and sands with variable horizons and the partially highly variable overburden loads, a combined pile-raft foundation or buoyancy protection with micropiles was implemented in the station area.
Special features
- Deviation from standard construction methods of RIL 853 in wide areas
- Manufactured using open-cut construction; monolithic connection of base/walls/ceiling with block lengths of up to 185 m in the station area/20 m in the line
- Monolithic connection of the station structure with the terminal building above, with local loads from the terminal of up to 20 MN; wall-like beams up to 60 m span for transferring the terminal loads
- In the station, double columns made of concrete C50/60, designed for impact/partial failure and fire (thermal design)
- Foundation of the station with combined pile-raft foundation (KPP) in the terminal area; in the remaining area, tensile anchoring against buoyancy with micropiles
- Partial prestressing of the station ceiling with unbonded post-tensioning (monostrand tendons)
- Two-cell tunnel beneath the airfield with loads from a 750 t design aircraft with
shallow overburden of 1.50 – 2.50 m; buoyancy protection through dead weight - Widening structures with variable width up to 60 m and up to 4 cells; eastern widening structure as a monolithic block with 116 m length and variable width; buoyancy protection with micropiles
- Consideration of two expansion stages with two satellite terminals above the line tunnel; thermal design with EBA temperature-time curve
- Multiple overpass of the airport’s road connection and foundation of the central pier of a road bridge on the tunnel
- Extensive interface coordination with the subsequent terminal shell construction as well as the
structures of the airside and landside development and with the later infrastructure operator DB AG, through whom the planning of the expansion took place
