Reliability of Design Approaches for Axially Loaded Offshore Piles Based on Field Tests

摘要

In the near future several offshore wind farm are planned to be built in China with relatively high water depths. For these jacket and tripod constructions with mainly axially loaded piles are suitable as support structures. The current design of axial bearing resistance of these piles leads to deviant results regarding the pile resistance when different Chinese code methods are adopted. Hence, also a strong deviation regarding the required pile length must be faced. The reliability of a design method can be evaluated on the basis of a model error which describes the quality of a considered design method by comparing measured and predicted pile bearing resistance. However, only few pile load tests exist with regard to the thick overburden layer in coastal region of China. This paper presents 2 field axial pile load tests which were incorporated within a model error approach for the current used design methods for the axial bearing resistance, namely API, USACE, NGI, Chinese Building Code, and Chinese Harbor Code method. In addition also the reliability of the introduced design methods was evaluated. It is shown that the Chinese code methods are not reliable and lead to a significant deviation, and the NGI method seems to be more suitable for the determination of the tensile capacity for offshore piles compared to the other investigated design methods.