Mechannical Response Of Pile Foundation In The Clay Under The Horizontal Cyclic Loading

As a commonly used structure in engineering construction,the pile foundation is not only subjected to the vertical effect caused by its own gravity and super structure,but also subjected to horizontal cyclicloading.Along with the fast development of Chinese economy,the construction of Marine engineering facilities is becoming more and more extensive,which is mainly affected by the cyclic load from oceanic wave loads,wind loads and ship collisions.For piles subjected to cyclic loading,many scholars at home and abroad have simulated the pile foundation as a linear elastic pile,and ignoring the effects of cracking of the pile body and steel yield.This article compares and analyzes the pile foundation model(which considers the factors of yield of the steel yield and the destruction of concrete)and the linear elastic pile foundation model,it is concluded that the model considering steel yield and concrete damage in engineering practice is more secure,and closer to the actual project.Especially under the influence of cyclic load with a large load amplitude,it is necessary to consider the steel yield and the destruction of concrete.By consulting the literature about the pile foundation subjected to horizontal cyclic loading and analyzing its design data,determine the parameters of the numerical simulation model,the numerical analysis model is established using a large-scale numerical analysis software ABAQUS,the soil adopts a combination hardening model and the concrete adopts concrete damaged plasticity model.,the elastic and plastic model based on the Mises yield criterion is used in the steel bar.By establishing numerical model simulation,according to the different cyclic loading and parameters of soil and pile foundation under the condition of physical parameters of pile displacement and bending moment of pile,pile body force of the results of numerical calculation,analysis and summarize the following conclusion:(1)With the increase of the number of cyclic loading,the residual deformation of the soil increased,the bending moment and shear force of the pile foundation and the size of the hysteresis loop also increased,but Its linear stiffness gradually become smaller.With the increasing load amplitude of the horizontal cyclic loading,the pile top displacement,the pile bending moment and the shear force become larger.(2)As to the influence of the character of the pile itself,increasing the concrete strength level and the reinforcement ratio of the pile foundation also can reduce the displacement,bending moment and shear force of the pile body,the influence of reinforcing steel reinforcement ratio is more obvious,but blindly increasing the reinforcement ratio of steel bars does not fully play the role of reinforcing bars,instead,it will cause a waste of resources.(3)The physical properties of the soil layer have a significant influence on the mechanical response of a single pile foundation under loading.It is known from the numerical simulation of a single pile foundation under difference undrained shear strength that the pile of a single pile foundation,the horizontal displacement of the pile body,the bending moment and shear of the pile and the residual strain of the soil in the pile are all decreased with the increase of the strength value of the pile.(4)The factors affecting the stress behavior of group pile foundations are reviewed,Stress analysis on pile number and group pile foundation under different horizontal cyclic loading angle,and the difference of the bearing behavior of each pile.With the increase of pile number,the bending moment and shear force of the pile foundation decreased obviously,the hysteresis loop decreased.With the increase of the angle of horizontal cyclic load,the bending moment and shear force of pile group along the forward loading direction increased.