Safety of Caisson Transport on a Floating Dock

摘要

When caissons are mounted on a floating transportation barge and towed by a tug boat in waves, the motion of the floating dock creates inertia-gravity induced slip force on the caisson. If its magnitude exceeds the corresponding friction force between the two surfaces, a slip may occur, which can lead to an unwanted accident. In oblique waves, both pitch and roll motions occur simultaneously and their coupling effects for separation and friction forces become more complicated. With the presence of strong winds, the separation force can significantly be increased to make the situation worse. In this regard, the safety of the transportation process of a caisson mounted on a floating dock for various wind-wave conditions is investigated. The analysis is done by both frequency-domain approach and time-domain approach and their differences as well as pros-cons are discussed. It is seen that the time- domain approach is more direct and accurate and can include nonlinear contributions and viscous effects, which are typically neglected in the linear frequency-domain approach.