Research On The Anti-collision System For Improving The Berthing Capacity Of Existing Overhead Vertical Wharfs

In China,the original designed berthing capacity of the in-service overhead wharves on inland rivers is generally small,but with the continuous improvement of the level of channel,the ships are becoming larger and larger.Under the background that river wharves have not been upgraded and rebuilt,when large ships directly dock at the existing wharf,the huge impact force generated by the collision is easy to cause damage to wharf components or structures,which seriously threatens the safety of the wharf.For this reason,a new type of floating anti-collision system is put forward in this paper,and the layout and material selection of the system are studied.The crashworthiness of the system was optimized by the finite element software ABAQUS.The main research work of this paper is as follows:(1)The ABAQUS finite element software was used to check the original anti-collision ability of the wharf structure.Through the simulation of ship berthing process with different tonnage,speed and Angle,it is concluded that the larger the ship tonnage and speed,the more intense the impact,the more full the energy transformation,the larger the peak value of impact force and the longer the action time of impact force.The actual impact force(about 10 MN)that the wharf can bear is obtained as the ultimate load by simulating the process of the original design of the 3000-ton ship docking at the wharf.When the wharf directly docks 5000-ton ships and 8000-ton ships,the impact force is 11.50 m N and 12.79 m N respectively,which is larger than the range of the original design of the safety impact force at the wharf and is not conducive to the safe operation of the wharf.(2)Combining with the practical engineering background of wharf,a new type of anti-collision buoyancy tank combining steel casing and rubber fender is put forward.By analyzing the advantages and disadvantages of each anti-collision device and its applicable conditions,and taking into account the berth,machinery and equipment,cost,etc.,the independent anti-collision buoyancy box form and the arrangement of the connection system for each berth are established.By calculating the impact energy,checking the rubber fender reaction force and finite element analysis of the connecting column,the energy absorption effect of the system and the bearing capacity of the connecting column are obtained to meet the requirements.(3)The ABAQUS was used to conduct numerical simulation analysis on the anti-collision buoyant tank.Nine calculation conditions are set for 3000-ton,5000-ton and 8000-ton ships to dock at 0.2m /s,0.5m /s and 1.0m /s at 0°,5° and 10° respectively.The calculation results show that the anti-collision buoyancy box can effectively prolong the energy conversion and impact force action time of the system,and the anti-collision buoyancy box can absorb the energy of the system through its own deformation,and the reduction rate of the impact force on the wharf can reach 52.11%.The anti-collision buoyancy tank can effectively protect the wharf during the berthing of large tonnage ships and high-speed ships.In the process of angular berthing,the contact area between the anti-collision buoyancy box and the ship is small,so the impact force reduction effect is not obvious,but the Angle of the ship can be adjusted.Under the protection of the anti-collision buoyancy tank,the original design of the 3,000-ton wharf can now dock8,000-ton ships,and the berthing capacity can be improved.(4)Based on the numerical analysis method,the structure of the anti-collision buoyancy tank is optimized.By changing plate thickness,longitudinal plate spacing and transverse plate spacing of buoyancy tank,different calculation conditions were set for numerical simulation.The calculation results show that the rubber fender first contacts the ship and participates in the collision,and absorbs energy through the deformation of the rubber fender,which greatly cushions the ship’s impact force and prolongs the impact time.Among the components of the anti-collision buoyancy box,the main energy-absorbing components of the steel structure layer of the anti-collision buoyancy box are deck,bottom plate,shell and inner shell.When the steel plate thickness,longitudinal plate spacing and transverse plate spacing are 8 mm,0.5 m and 0.75 m respectively,the anti-collision performance of the anti-collision buoyancy box is the best.