Study On The Coupled Motion Responses Of The Crane Vessel "Lanjing" And The Topside During Lifting Operation In Beam Waves

Offshore platforms play an important role in the exploitation of deep-sea oil.Lifting operation is a common method of platform installation.Lifting operation needs to be completed by crane.Therefore,it is significant to study the coupled motion response of crane ship during lifting to avoid some accidents.In this paper,the response of the crane ship and the topside is calculated about "Lanjing" crane ship,and a model test is carried out.Sometimes the crane ship can only under construction in the beam waves due to the limitation of actual condition of the sea.At the same time,in many cases,the ship will be affected by multiple waves during the construction process,which may include waves.Therefore,this article mainly analyzes the physical mechanism of the topside in the beam waves.The research topic has good theoretical significance and engineering value.In this paper,the coupling motion response model test of the mooring lifting process of the "Langjing" crane ship is introduced.First of all,tests were carried out in static water,and viscous damping of lifting vessels and the topside is obtained through analysis.Secondly,the coupled motion of ship-topside coupling under regular wave and irregular wave sea condition is analyzed,and the coupling motion response rule of the ship and the topside under different wave direction,different lifting weight and different lifting height is analyzed.In the model test,it is found that,in the beam wave,when the wave period is close to the inherent period of the ship's rolling,the mooring ship will resonate with the wave,and the movement of the topside is more intense.When the wave period approaches the natural cycle of the block,the coupling resonance will also occur,and the motion will obviously increase.The combination of three-dimensional potential flow theory and motion equation method is carried out for the complex coupling system,including the beam waves,the mooring system,the crane ship “Lanjing”,the crane sling and the topside,to analyze the coupled motion response rule and characteristics of the topside.In the regular wave,the simulation results of the empty ship and the block are compared with the model test results,and the rationality and accuracy of the numerical simulation are verified.It is found that the movement of the block in the cross wave is more complex.It is also found that when the wave period approaches the natural period of rolling and the natural cycle of the block,the movement of the upper block will increase obviously.The results are consistent with the results in the model test,and reveal the coupling movement mechanism between the crane ship and the topside.The statistical results of topside motion in irregular waves are compared with the statistical results in the experiments.In view of the two sensitive parameters of lifting height and lifting weight,their influence on the natural cycle of the upper block is analyzed.It is found that the natural period of sway and the natural period of sway gradually decrease with the increase of hoisting height,which is independent of the weight of the block.The movement of the topside under four irregular waves is analyzed and compared with the range of motion allowed in the Nobel Denton guide manual,and some suggestions are given to allow the working conditions of the construction work.