Interactions between multi-directional irregular waves and a pile group in a side-by-side arrangement: Statistical analysis

Pile groups are widely used structures in coastal and ocean engineering, such as in cross-sea bridges and offshore wind turbine foundations. The effect of a pile group must be considered when calculating the wave forces on piles. In addition, real sea waves are multi-directional waves. However, the associated regulations and studies have mainly concentrated on the action of a unidirectional wave on pile groups. Few studies have considered the interactions between multi-directional irregular waves and pile groups. In this study, we experimentally investigated the interactions between multi-directional irregular waves and a small scale, vertical bottom-mounted pile group comprising nine piles in a side-by-side arrangement. We propose a new parameter: KCLD1/3 = KC1/3 x L/D, to comprehensively consider the effects of the relative pile diameter D/L and KC1/3 number on the wave inline force and transverse force on piles. The results show that directional spreading has a significant effect on the interaction between multi-directional irregular waves and piles, especially on the transverse force of piles. The relationships between the inline force, transverse force, and resultant force are studied, and the differences in the wave force among different piles are determined. These results may provide a reference to facilitate the design of engineering structures.