Scouring processes in harbour basins during the docking and undocking manoeuvring: laboratory experiments

Abstract

Scouring processes due to manoeuvring actions can produce big consequences on the stability of harbour structures such as docks and protecting dikes. As a consequence, the sedimentation of the eroded sediment reduces the total depth of the harbour basin and navigation channel. At the same time, contaminants settled at the bed of the harbour basins may be resuspended by the effect of vessel’s propellers and produce an important environmental problem to harbour authorities. Present formulas to compute the total scouring depth have revealed to overestimate the maximum scouring depth or be non-realistic in other cases. Experiments performed at the Marine Engineering Laboratory in LaBassA flume (12x4.6x2.5 m³) with a twin propeller reduced model of 0.25 m diameter are presented herein. Main propeller and bow thruster conditions are evaluated for three different rotating velocities using a sediment diameter of D50 = 250 µm at bollard pull conditions.