Three-Dimensional Numerical Analysis of Jet-Induced Local Scouring in Front of Quay Walls and Its Countermeasure Using Filter Units

Abstract

A bow thruster mounted in the bow of a vessel is generally used to improve its maneuverability in ports. When a bow thruster is used near a berth, a jet generated from the bow thruster can cause sediment transport, resulting in local scouring of the seabed in front of quay walls. Countermeasures against such scouring are essential to ensure the stability of the quay walls. In recent years, new protective units called filter units have been used to protect seawalls and river dikes. However, it remains to be determined whether filter units covering the seabed in front of quay walls are effective in preventing jet-induced local scouring. In this study, jet-induced local scouring in front of a quay wall and its countermeasure using filter units are investigated using a three-dimensional two-way coupled fluid-sediment interaction model. The predictive capability of the three-dimensional coupled model is verified against experimental data in terms of average jet flow velocity, pore-water pressure, and the final seabed profile. The results show that the filter units covering the seabed prevent negative effective stress fluctuations on the surface layer of the seabed, and demonstrate the effectiveness of the countermeasure using the filter units.