Zusammenfassung
Summary
To enter the port of Hamburg, a tidal estuary of about 120 km, the Low and Outer Elbe has to be traveled. Groynes, rigid hydraulic structures, were established to help exploitation of the river as a federal waterway and protect the riverbanks. Since 2001 various damages of groynes have been observed deeming a costly repair and maintenance necessary. The cause was detected in the increasing maritime traffic of larger sized vessels. Vessels induce heavy long-periodic wave loads eroding the structures and creating breakthroughs at the groyne’s coastal connection. At the Low Elbe section Juelssand, an in situ pilot study by the Federal Waterways Engineering and Research Institute and the Waterways and Shipping Board, new construction parameters and different shapes at real conditions are tested for a probabilistic assessment of the groyne’s revetment. The documentation of the deformation is based on a geodetic monitoring system developed and operated in cooperation between Federal Waterways Engineering and Research Institute and HafenCity University Hamburg. Encapsulated in a secure housing, a laser scanner automatically records the groyne’s surface at each low tide. Two identical measurement systems were installed on monitoring platforms at 12 m height documenting two different groyne types. Based on the laser scans, a 3D comparison is calculated to detect changes to a reference epoch to quantify the impact of ship passages. Additionally, important vessel parameters are gathered from the Automatic Information System (AIS) while wave loads are measured with pressure probes installed well distributed at the groynes.