Swinging Control of a Pile during Lifting Construction

The construction of offshore vessels is affected by swell waves, and the swinging and rotation of the slender pile foundation components lifted by pile driving vessels are crucial indicators of their operability. The construction operability should take the impact of the swell waves into consideration. However, due to their multi-directional and irregular characteristics, the swell waves should be described using a two-dimensional spectrum. Considering the influence of the two-dimensional wave spectrum on the lifting process, and to avoid the time-consuming time-domain calculations, this paper proposes a dynamic analysis method for multi-cable systems allowing to accurately analyze the swing control. This approach is based on the motion response spectrum and frequency-time domain conversion method. The lifting and damping cable parameters of swing control are taken into consideration to study the motion response characteristics of slender foundation piles in order to be able to control them. This allows to significantly improve the operability. Taking the large-diameter pile foundation driving in the open sea as an example, the lifting characteristics of the pile foundation under the action of waves are studied, and the motion characteristics and swinging suppression rates for different parameters are then obtained. It is deduced that for the same parameters of the cable, when its diameter increases, the suppression effect also increases. In addition, increasing the cable stiffness allows to cope with the sway oscillation of the pile. This dynamic analysis method quickly calculates the motion response parameters for swinging control, avoiding a large number of time-domain coupling calculations between ships and pile foundations. Therefore, it has a great application value in this domain.