In this study, a numerical model is adopted to investigate the wave-seabed interactions around offshore wind turbine four–pile jacket foundation. Unlike the previous study, irregular wave loading will be considered. The present model is adopted from PORO–FSSI–FOAM solver, which was based on the olaFlow solvers for wave motion, the Biot equation for the porous seabed. The present model will be validated with the recent wave flume test for random wave–induced pore pressures around a mono–pile. The irregular waves generated by diverse spectra, such as the JONSWAP spectrum etc., propagate forward from the inlet boundary. The numerical simulation consequences manifested that the maximum value of the pore pressure and soil liquefaction depth became greater in the irregular wave system, compared with the cases with regular waves. Furthermore, the random distribution of the fluid velocity and the soil response is observed, which is attributed to the irregularity of waves.