Numerical study on the stability of offshore pile-soil systems considering pore pressure response induced by extreme storms

The accelerating climate crisis has intensified global efforts to develop renewable energy, with offshore wind power emerging as a key solution due to its vast potential and low environmental impact. However, the stability of offshore wind turbines (OWTs) is increasingly compromised by extreme storm events, such as typhoons, which induce strong winds, large wave loads, and seabed liquefaction. While extensive research has been conducted on monopile foundations, most studies focus either on horizontal loads or seabed responses in isolation, lacking a systematic analysis of the coupled pile-soil interaction in extreme storm conditions. This study develops a pilesoil interaction model incorporating pore pressure response to evaluate the stability of monopile and seabed under extreme storm loads. The model is validated using seabed pore pressure models under wave action and monopile response models under cyclic loading. The model is applied to the stability analysis of monopiles at the Cangnan offshore wind farm, where extreme storm loads are quantified using buoy measurement data and incorporated into the model to calculate the responses of both monopiles and seabeds. The results show that the monopile displacement reaches its maximum at the wave crest, and the displacement and moment of the monopile are positively correlated with wave height and negatively correlated with wave length and period. Although changes in wave parameters do not affect the failure mode of the soil, they influence the magnitude and distribution of pore pressure around the pile. The findings provide critical insights into offshore wind turbine foundation stability, offering a scientific basis for improving design strategies to enhance resilience against extreme weather events.