In recent years, many wind farms have been built in offshore areas. Among all kinds of foundations, monopile foundation is an important type to support these offshore wind farms. Previous studies mainly focused on using cyclic or monotonic mechanical loading to simulate the actual loading on the monopile in the ocean. Thus the relationship between wave, soil and monopile has not been well studied. So the objective of this study is to investigate the large-diameter monopile behaviour under wave loading in sand.

In order to produce wave in the centrifuge flight, a wave tank was used in the test. This wave tank is able to work at up to 100 g in the centrifuge. The wave tank includes wave generator, wave absorber and a model box. With the help of hydraulic actuator and servo-valve...[ Read more ]

In recent years, many wind farms have been built in offshore areas. Among all kinds of foundations, monopile foundation is an important type to support these offshore wind farms. Previous studies mainly focused on using cyclic or monotonic mechanical loading to simulate the actual loading on the monopile in the ocean. Thus the relationship between wave, soil and monopile has not been well studied. So the objective of this study is to investigate the large-diameter monopile behaviour under wave loading in sand.

In order to produce wave in the centrifuge flight, a wave tank was used in the test. This wave tank is able to work at up to 100 g in the centrifuge. The wave tank includes wave generator, wave absorber and a model box. With the help of hydraulic actuator and servo-valve, the wave paddle can move horizontally to generate wave. The wave absorber is put at the opposite side of the wave generator in the model box so that it can minimize the influence of reflected wave.

In this research, the centrifuge test was conducted in the wave tank at 100 g, which was mainly about the behaviour of monopile. The model pile was located in the sand with wave loading being applied to it. It was found that in each cycle of wave loading, with the increase of soil depth, the maximum bending moment of the pile firstly increased and then decreased. The peak value of the maximum bending moment occurred at around the middle embedment depth of pile. The curve of minimum bending moment in each cycle had a similar trend with the maximum bending moment. When the wave loading was applied to the pile, the pore pressure in the sand near the pile increased in the beginning and then gradually decreased.