Settlements of offshore wind turbine foundations impacted by submarine landslide debris

Submarine landslides are among the most serious problems for offshore wind turbine foundations. Understanding the interaction mechanism of submarine landslide/offshore wind turbine foundation is essential for risk assessment, but it is challenging due to its complexities. In this study, centrifuge tests were conducted to determine how offshore wind turbines founded on four piles with pile length of 10, 15, and 20 m, respectively, in clay respond to submarine landslides. Based on the tests, it was found that: (1) excess pore water pressures reached a peak when hit by the landslide and then dissipated to a residual value. The peak pressure was 24 kPa in clay around the 10 m pile foundation and about 18 kPa for the 20 m pile foundation. (2) Settlements of the wind turbine foundation largely depended on the dynamic impact of the landslide and decreased with the length of the pile. The settlements were 0.5 m for the 10 m pile foundation and about 0.1 m for the 20 m pile foundation. (3) Deformation of the clay was associated with induced excess pore water pressure, while was quite insignificant, compared to the foundation settlement.