| The catenary anchor leg mooring system uses a large-diameter cylindrical buoy as the main body,which is fixed on the seabed foundation by catenary anchor chain.The tanker is moored on the mooring boom of the pontoon swivel arm by cable.Under the combined action of wind,wave and current,the tanker can rotate around the mooring point.The calm system is a flexible nonlinear structure,and the coupled hydrodynamic response of a large ship moored with two floating bodies is very complex.The inherent nonlinearity of a single point mooring system makes the dynamic response of an oil tanker difficult to predict due to its nonlinear dynamics and instability,and even the horizontal motion becomes chaotic and unpredictable.The system can be used as a transport terminal in the open sea.At present,there is only one set of imported equipment in China.One of the reasons why China does not have the capability of independent design of calm is that it does not fully grasp the dynamic response law of CALM system under the combined action of wind,wave and current.Based on the physical model test method,the dynamic response of the system under the combined action of wind,wave and current is studied,focusing on the self storage capacity of the system,the movement law of CALM mooring of 300000 DWT tanker and the allowable operation standard.The results show that:(1)CALM mooring system of 300000 DWT tanker has a strong self storage capacity.Effective wave height 3.5m In the wind wave field with a period of 8s,the ship mooring line and calm mooring line still have a safety factor of 4-5 times.Effective wave height Hs = 6m,peak period TP= 10.4s;flow rate 1.2m/s;wind speed 27.9m/s Under the action of dynamic combination,when 6 cables are complete,the safety factor is about 3 times compared with the breaking strength of anchor chain(considering corrosion).When 6 anchor cables break 1,the safety factor is reduced to Two about.(2)CALM mooring system of 300000 DWT tanker has a strong marine dynamic adaptive ability.When the wave current and wind are different,the system will automatically adjust to the dynamic balance of direction mooring state.However,it is necessary to have tugs in the direction of mooring line behind the ship,which can effectively reduce the movement range of the ship.The increase of wind speed and velocity has the most significant effect on the ship's surge motion(increasing the tension of ship cables and some buoy cables),but has no significant effect on other motion components of the ship.(3)When a single buoy cable breaks,the tension of the adjacent cable increases about 30%.The maximum variation of ship motion is mainly the sway and surge motion components,while the other motion components have little change.The amplitudes of sway and surge motion components are about 8% and 25% respectively.(4)The allowable operation standard of CALM system of mooring 300000 DWT tanker is controlled by the water depth of mooring water.When the 300000 DWT ship is fully loaded and the chart water depth is more than 26 m,the operation dynamic conditions limited by the ship motion and restraint system are very broad: When the flow velocity is not more than Two point five and the wind speed is 9,it is allowed to operate in the wind and wave field with no more than Hs = 3m and the peak period Tp = 10 s.Chart water depth is limited to twenty-four point five When the water area is meters,the dynamic condition of operation is controlled by the bottom touch of the ship.It is suggested that the ship should be unloaded and moored in this water depth: when the draft of load reduction CHB1 reaches 21 meters,the operation can still be carried out under the same dynamic condition of 26 m water depth. |
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