Analysis Of Spudcan-seabed Collision Of Jack-up Wind Turbine Installation Ship

Jack-up wind turbine installation ship needs to put piles on the seabed when it takes the wind turbine generator set into place,and the installation operation can only be carried out after the pile legs stand firm.However,due to the influence of environmental loads such as wind,waves and currents and the shape of the seabed,the spudcans at the bottom of the pile legs may touch the soil near the seabed,and the force or moment between the pile shoes and the seabed is too large,which will damage the spudcans,legs and other structures and affect the structural safety of the whole installation ship.Therefore,it is of great significance to study the bottom collision of jack-up wind turbine installation ship.Based on the joint enterprise research project of jack-up wind turbine installation ship under two working conditions of semi-support and bottoming,which was released by DNV,the simplified modeling of jack-up wind power installation ship,simulation of spudcan-seabed collision,frequency domain and time domain analysis and simulation of spudcan-seabed collision structure were carried out by drawing lessons from the structural design and analysis methods of spudcan-seabed collision at home and abroad.Firstly,the basic research method of spudcan-seabed collision is discussed,and a simplified model of jack-up wind turbine installation ship is established.After verifying the hydrodynamic model,the motion response of the whole platform during the lowering of the pile legs of the installation ship is calculated,and the short-term statistical prediction of the motion response of the installation ship is made,which provides a feasible method for determining the lowering height of the final bottoming.Based on Kelvin-Voigt linear spring damping contact model,a 3-degree-of-freedom spring-damping system is established to describe the collision between spudcans and seabed,and the coupling analysis of hydrodynamic analysis and impact analysis is carried out.The contact force between spudcans and seabed under various soil conditions is analyzed and compared with the empirical formula given by DNV,which proves that the method used by DNV is a conservative estimate.In addition,the weather window of installation ship is evaluated by assuming the collision safety factor.Finally,the finite element model of pile shoe-seabed structure is established,and the yield strength of spudcan is checked.The analysis shows that the strength of all structural units conforms to the code.Based on the transient dynamics theory,the influence of sea conditions and collision angle on spudcan-seabed collision is analyzed,and the stress distribution law is studied.The results show that the contact force between spudcans and seabed under sand or clay is much less than the yield strength of spudcans material,which basically does not lead to the structural damage of spudcans.In addition,the interaction between spudcans and seabed tends to increase with the increase of sea state grade and collision angle.