94 / 2025-04-24 12:55:58

Erosion behavior assessment for scour prediction of Japanese offshore sand using Erosion Function Apparatus (EFA)

Scour, the erosion of seabed materials caused by water flow, threatens offshore structural stability. While prior research explored scour around piles in cohesive soils, studies on sandy grounds remain limited. This study evaluates scour depth around a 10 m-diameter monopile installed in Japanese offshore sand. Erosion Function Apparatus (EFA) tests quantified critical shear stress, erodibility coefficient, and power exponent for four soil layers. Results show that S3 is the most erosion-prone due to its low critical shear stress, while S4 demonstrates higher resistance to scour compared to other layers. Using SRICOS-EFA analysis and 25 years of discharge data, the maximum predicted scour depth was 1.6 m, with significant erosion starting in year 5 and removing most of layer S1. Due to the limitations of unidirectional flow data, multi-directional discharge and improved soil characterization need to be incorporated in the following studies.