Experimental study of pressure distribution and wave forces on pile groups under extreme waves

Pile groups frequently subjected to extreme wave loading are crucial for the structural integrity of marine infrastructure. However, research on the pressure distribution and wave forces of pile groups under extreme wave conditions has not been explored in depth. This paper investigates the pressure distribution and wave forces on pile groups under laboratory-generated extreme waves, considering nine wave scenarios and three pile group configurations. Investigations were conducted on the integration of pressure along the circumferential direction (IPC), the peak value of wave forces (Fxm), and the ratio of the Fxm of pile groups to the Fxm of a single pile (Rc). Experimental results indicate that: In both the vertical and circumferential pressure distributions, pile groups with different configurations exhibit the same distribution characteristics as a single pile. Pressure, IPC, and Fxm are positively correlated with wave paddle velocity. Pressure generally increases with water depth, and the circumferential pressure distribution follows Bernoulli's principle. The analysis of the vertical pressure distribution reveal that the mechanisms governing the variation of static and dynamic pressure are different at above-water and underwater measuring points. The Rcvalues of side-by-side configuration are greater than 1 under most scenarios, whereas for tandem and 2 x 2 configurations, the Rcvalues are less than 1 basically. This research offers fundamental insights into the design of marine infrastructure under extreme oceanic conditions.