Experimental Study On The Hydrodynamic Characteristic And Anti-collision Performance Of Buoy Chain Anti-ship Collision System

The anti-ship collision system in the early stage is mainly the integration of anti-collision structure and the collided structure. It further develops a variety of flexible anti-collision structure. The latest tendency is the separation of the anti-ship collision system and the collided structure to ensure the safety of the collided ones thoroughly. The mooring buoy chain is one of them. Though with the advantages of a relatively low cost, convenient construction, easy to repair after damage and adaptable to deep water and various foundations, the new type anti-collision system has limited application by the lack of systematic study on hydrodynamic characteristic and anti-collision performance and absence of codes and standards at home and abroad for the engineering design.This paper makes comprehensive research on hydrodynamic characteristic (movement and stress state) and anti—collision performance of the mooring buoy chain system of the anti-ship collision device by physical model test for South Liquid Chemicals Wharf No.2in Gulei Zone of Gulei Port, Xiamen, Fujian and comes to the following results:(1) When the diameter of the Buoys in the buoy chain system is2m and the tensile capacity of the mooring chain is1,000KN, the tension of the5m wave heights wave on the mooring buoys is less than that of the2,000DWT ship with the speed of0.5m/s.This system can resist the tension of the2,000DWT ship with the speed of1m/s.(2) When the diameter of the Buoys in the buoy chain system is4m and the tensile capacity of the mooring chain is3,000KN, the tension of the5m wave heights wave on the mooring buoys is less than that of the5,000DWT ship with the speed of0.5m/s.This system can resist the tension of the10,000DWT ship with the speed of0.3m/s.(3) The stress on the mooring lines and connecting chains between the buoys is related to the impact area and impact attitude. The destructive power occurs when the ship with full load has the positive effects on the buoy system. (4) When the ships in the free form knock on buoy system, the wind speed and the water velocity play a major role. The waves contribute little to the tension of the mooring cable.(5) For the tension of the connecting chains between the buoys, the critical impact area occurs when the ship has the positive impact on it; and for that of the mooring lines, the critical impact area occurs when the ship has the positive impact on edge of buoys.(6) For the wirerope mooring system, the initial tension of the mooring wire in the mooring system has enormous influence on the max. mooring tension when the ship attacks on the buoys. The requirements for the initial tension of the mooring system shall be the0of the initial tension of the wirerope under the max. water level and max. allowable buoy displacement.(7) Buoy chain mooring system always moves in S-shape under the hydrodynamic force (wave, tide). Though wind contributes not much to the momentum of the buoy system, it can increase the high-frequency pulsation of the S-shaped motion. When the ship attacks, the state of the buoy chain system is the normal state under the hydrodynamic force superimposes arch forming part.