Research On Dynamic Response Of Mixed Pile Under Ship Impacting

In bridge deep foundation,,in order to reduce ship collision risk and improve the lateral stiffnessof pile foundation,the steel tube is usually retained in the construction of large diameter boredpile.Therefore,it becomes a mixed pile that its internal structure is steel concrete and its exteriorstructure is concrete filled steel tube.This paper mainly researches the horizontal bearing charateristicsand the dynamic response under ship impacting of mixed pile. The research methods are as follows:Frist, ignoring the pile-soil interaction,the FEM model of mixed pile is created by finite elementsoftware, and to research the computational model of combinatorial flexural rigidity.Second, the FEMmodel of mixed pile that contains the pile-soil interaction is created by finite element software,thehorizontal bearing characteristics of mixed pile are researched by the factors such as steel ratio, elasticmodulus of pile,the thickness and elastic modulus of mud layer.The indoor model test is carried out,and the models of mixed pile,ship and soil are built tosimulate the ship-cap collision.Besides, the FEM models are created to simulate the impact betweenship and pile cap,the numerical simulation results are compared with the experimental results to studythe dynamic response of mixed pile by the factors such as weight of ship,velocity of ship, steel tubewall thickness,length over the ground of pile, vertical load on the cap, diameter of pile, mud layer anddynamic shear modulus of soil.The results of this paper are as follows:The mixed pile structure has obviously effect for improving the horizontal bearing charateristicsof pile foundation.The improving of steel ratio and elastic modulus of pile is useful to the horizontalbearing charateristics of pile foundation, however, the mud layer has an unfavorable influence onit.The mixed pile structure has great benefits in reducing the ship collision risk and improving theflexural rigidity.The weight of ship, velocity of ship and diameter of pile have a significant effect onthe maximum displacement of the pile cap,the maximum acceleration of the pile cap,the maximumship impacting force and the pile body maximum tensile stress. The steel tube wall thickness and thelength over the ground of pile have a significant effect on the maximum displacement of the pile capand the pile body maximum tensile stress, however,they have a little effect on the maximumacceleration of the pile cap and the maximum ship impacting force.The dynamic shear modulus ofsoil has some influences on the response of mixed pile.The mud layer has a negative impact on theresponse of mixed pile.