Online‐Monitoring des Temperaturzwangs für ein Trogbauwerk am Hauptbahnhof Berlin infolge Kopplung des Trogs mit der Unterwasserbetonsohle

Online‐monitoring of thermal restraint for a trough structure at the main station Berlin caused by the coupling of the trough and underwater concrete slab. At the main station of Berlin the North–South and East–West main railway lines intersect. The N‐S lines are located at the lowest level of station. They run on both sides of the station in tunnels. The trough structure N begins at the northern end of tunnel and guides the N‐S lines to ground level. The structural design of trough proved to be complex. The high ground water pressure required the coupling of the trough slab with the underwater concrete slab being back‐anchored by injection piles. These piles had to be extended into the trough slab and anchored there. For the coupling of the slabs several structural alternatives were investigated, in order to study their effects on the restraint of the trough slab due to temperature and shrinkage. Studies showed that the temperature load requirements of existing specifications in‐adequately reflect the representative winter situation of Berlin. Realistic temperature values were derived on basis of meteorological and thermal analyses. For the assessment of the efficacy of shear bond between the underwater concrete slab and trough slab, on‐site tests were performed. Expert opinions formulated the necessary design values. In view of the complex structural model of trough and of various assumptions, the owner DB decided the online monitoring for a representative trough. Monitoring is being performed by the MPA Braunschweig. Measurements commenced in July 2003 with the casting of the trough slab and will continue well into the service stage of structure. This report deals with the measuring techniques and with the results prior to the on‐set of railway traffic. All assumptions relevant to the thermal restraint could be verified by the measurements.