The equilibrium depth of wave scour around both slender and large piles

Abstract

The equilibrium stage of the scour caused by the wave effect around the marine piles was investigated experimentally for both slender and large piles. Unlike the experimental studies in the literature, some of the experiments were carried out under clear water scour condition, since the coarse bed material was used in the present study. While the effective parameter on scour for slender piles is only the Keulegan-Carpenter number, it is understood that the diffraction parameter is also effective for large piles. It has been determined that when the steady-streaming structure around a large pile is effective, the scour increases with the increase in the Keulegan-Carpenter number and the diffraction parameter. For the estimation of the relative equilibrium scour depth around the slender piles, the results were evaluated together with the previous experimental study results and a new empirical equations based on the Keulegan-Carpenter number (KC > 4) was proposed. A new empirical correlation is derived, which includes the Keulegan-Carpenter number and the diffraction parameter (10−3<D/L < 3·10−1) for both slender and large piles. In addition, alternatively, a new equation is proposed using the modified Ursell parameter (Urp<105). The nominal limit of the relative scour depth according to the diffraction parameter was determined as 0.0082·(D/L)−1.