Large-scale experiments and load transfer analysis of piled foundations supporting an offshore wind turbine

In water depths exceeding 35 - 40 m wind converters will most likely be supported by multipod sub-structures founded on deep foundations. Due to the relative light weight of offshore wind turbines, piled foundations will be subjected to both compressive and tensile loading. To expand the knowledge regarding ultimate capacity and behavioral patterns of piles in tension, large-scale tests have been conducted in the Test Centre for Support Structures of the Leibniz Universität Hannover. Five piles with five different embedment ratios (embedded length 5 to 7 m) and two distinct diameters (273 and 355 mm) were installed and subsequently quasi-statically tested in sandy soil. In this contribution the test campaign is described, the experimental results are presented and the applicability of CPT-methods is discussed. In addition, the applicability of load transfer curves as further and more sophisticated prediction technique is analysed. The test campaign was performed within the framework of the European Union research project IRPWind.