Study On Large Deformation Characteristics Of Elevated Pile Subjected To Ship Impact And Flexible Piled Anti-collision System

Along with the rapid development of global economic, the generation of water structure increases drastically around the world, such as bridge piers, transmission tower and offshore drilling platforms, which will be seriously affected by ship impact. It is significant to study the anti-collision design methods and the anti-collision systems for these structures. Until recently, most of anti-collision design methods is based on impact force control. Whereas, the flexible elevated piled structure will exhibit large deformation subjected to the impact force, and absorb the impact energy by the deformation of itself, the traditional anti-collision design method is no longer applicable. So studying the lage deformation characteristics of the elevated piled structures and the new anti-collision design method is required.Based on the known "m" method and p-y curve method, the finite-differential programs is developed to study the lateral deformation characteristics of the elevated piles. Large-scale model tests are carried out to study the large deformation characteristics of the elevated pile, and the pile shaft lateral deformation and bending moment are measured. The relationship between shaft lateral displacements, bending moments and soil reactions is established, and a reasonable hyperbolic p-y curve model is proposed. It is found that the pile cantilever length much influences the pile shaft lateral displacement and bending moment. The pile shaft lateral displacement is almost bilinear to the ratio of pile cantilever length, and the pile shaft bending moment is almost linear to the ratio of pile cantilever length.Based on the dynamic p-y curve method, a dynamic model is presented for the collision analysis of the elevated piled structure subjected to a moving ship. With the model, the energy transfermation and the deformation of the elevated piled structure during the collision are studied. It is found that the impact energy mainly transfers to the pile foundation and the relationship between the impact energy and the moment of the pile shaft is given. It is found that there is little difference between results analyzed by static p-y curves method and dynamic p-y curves method respectively. Thus, the static p-y curve method can be used to analyze the elevated piled structure subjected to the ship impact. Further, an anti-collision design method based on energy control for the elevated piled structure is presented, and a new flexible pier-supported anti-collision system is proposed. Finally, these new anti-collison system and new design method are applied to a specific engineering case.