Dynamic Response Analysis Of Collision Process Between Ship And Ship Pile

With the introduction of the Maritime Silk Road,the modern water operation industry has flourished and the frequency of ship transportation has increased significantly.When the ship is berthing and loading and unloading operations,it is often subjected to the impact and extrusion of the ship at the front part of the wharf.Among them,the impact of the impact on the structure of the wharf is the most obvious,it may cause damage to the structure or even the collapse of the dock,the impact on the economy and the casualties of personnel is immeasurable.In order to prevent such accidents,it is necessary to protect the wharf buildings and the ships themselves.The general practice is to install anti-shock equipment on the front edge of the wharf.The ship pile is a kind of anti-shock equipment,and its main function is at the front of the wharf.Directly withstand the impact load of the ship,absorb the energy generated by the ship’s impact through the deformation of the pile itself and the fender.In order to further optimize the type and arrangement of the ship’s pile,it is necessary to carry out research on the collision between the ship and the ship’s pile.In this paper,the finite element model of ship and flexible ship pile collision is established by ANSYS finite element software,and the model is numerically solved by LS-DYNA program.The force mechanism of the ship impacting the flexible ship pile,the ship impact force,rely on The ship pile response and the energy conversion of the entire collision system were analyzed and compared with the theoretical calculations in the specification.The main contents and conclusions of the paper are as follows:（1）The ANSYS/LS-DYNA is used to establish the numerical model of ship impact flexible ship pile.The impact force curve of the ship impacting flexible ship pile is approximately parabolic.The ship is in the initial stage of impact,due to the flexibility of the ship pile itself,basically Experienced a second impact at different times.In the collision process between the ship and the flexible ship pile,the essence is the process of energy exchange,and at the same time it is consistent with energy conservation.The initial kinetic energy of the ship（which includes additional water quality）is converted into the internal energy,residual kinetic energy,hourglass energy and slip energy of the bow and steel pipe pile,while the slip energy is mainly generated in the time period near the peak of the impact force.（2）The impact force peaks of ships with different tonnages of 500t,1000t,1500t and 2000t in different tonnage rivers were analyzed and compared.When the tonnage is small,the peak of the impact force has a similar linear relationship,but as the tonnage increases to 2000t,the increase of the impact force peak decreases,and the impact force no longer has a linear relationship.Because of the plastic deformation of the material of the bow or the pile,the increase of the tonnage significantly increases the duration of the impact and delays the peak of the impact force.（3）The effects of the initial velocity of the ship at 0.2m/s,0.4m/s,0.6m/s and 0.8m/s on the impact of the ship’s pile are discussed.It is found that the impact speed has an impact on the impact force than the tonnage.The impact is much greater.At the same time,when the impact velocity of the ship at 2000t is 0.6m/s,the ship pile does not return to the initial position before the impact,indicating that the pile body has reached the damage at this time,and it can also indicate that the pile pile is yielding.The adjacent points of failure are at a collision speed of between 0.4 m/s and 0.6 m/s.（4）The influence of the elastic modulus of sand on the flexible piles is studied.The influence of the elastic modulus of the sand on the impact of the flexible piles is not great.Before the peak is reached,the impact curves of different elastic modulus are basically Coincidence and the trend are basically the same,only slightly affecting the entire collision process time and peak,and the difference is not big.At the moment when the ship is in contact with the steel pipe pile at the beginning of the impact,the steel pipe pile has an influence on the soil inside the pipe.As the collision process progresses,the soil stress on the right side of the steel pipe gradually increases.After the collision process,the ship rebounded,and the steel pipe pile was slowly restored by its own flexibility.The vibration of the steel pipe pile itself caused stress on the left side soil.It is found through the stress cloud diagram that the stress on the soil is far less than the stress on the steel pipe pile,indicating that the soil has little effect on the entire impact process.（5）The wall thickness of different steel pipes is equivalent to the different bending stiffness of the structure.When the inner diameter of the steel pipe pile is thickened to 30mm,the maximum displacement of the pile top is reduced by 35mm compared with the wall thickness of 20mm,and the larger the wall thickness is,the structure is reduced.The greater the stiffness,the greater the impact time,the greater the impact force,and the smaller the displacement.The reason is that the bending rigidity of the structure is increased,resulting in a decrease in the absorbed energy,less internal energy absorption,and an increase in the impact force corresponding to the kinetic energy.At the same time,the larger the wall thickness,the smaller the displacement of the pile top.