Dynamic Analysis of Floating Dock Operations with Corrosion-induced Holes at Ballast Tanks
Abstract
The corrosion at the ballast tanks is a concern risk for floating docks that have been inservice for several decades. Corrosion events can result in severe accidents and huge economiccosts. To migrate the corrosion risk, the dynamic response of a floating dock under corrosion-inducedaccidents are studied using a numerical method. The numerical model is proposed tocalculate the dynamic responses of the floating dock during operations. It includes a six-degree-of freedom(6-DOF) model, a hydrostatic force model, a hydrodynamic force model, a hydraulicmodel, and a modified P-controller. The hydraulic model is proposed to model the flow through thevalves and pumps as well as the corrosion-induced holes. The investigated floating dock isequipped with 18 ballast tanks, which are exposed to corrosion due to the seawater. The influenceof the position and the diameter of the corrosion-induced holes on the stability and the dynamicbehavior of the floating dock at its work position and during the ballasting and de-ballastingoperation are studied numerically using the proposed model. For the corrosion-induced ballastingof the floating dock at its working position, the maximum pitch and roll angles are 0.42 degreesand 2.04 degrees respectively when there are one or two holes located at different tanks. For theautomatic ballasting with corrosion-induced holes, the maximum roll and pitch angles during theoperations are found to be proportional to hole diameters. With two 300 mm-diameter corrosion-inducedholes at different ballast tanks, the present modified P-controller is able to regulate the floatingdock's pitch and roll angles within very small ranges. For the automatic de-ballasting withcorrosion-induced holes with a diameter of 300mm, the presence of automatic ballast controlcouldn’t keep all cases within a safe margin because some special locations of the corrosion-inducedholes cause large trim and roll moments. This analysis can emphasize the potential hazards ofthe corrosion-induced holes and presents an opportunity for the maritime sector to enhance safety,operational efficiency, and environmental responsibility.