Pile-soil-the Upper Structure, Mechanism And Numerical Simulation Under The Impact Of Earthquake

Pile foundation is a basic form which has a long history and has been used widely.With a variety of high,large,heavy,deep structures emerging people put forward higher requirements to the foundation of buildings.Pile foundation is widely used for its large bearing capacity,good stability,excellent seismic performance,well adapt to the building foundation and extensive types of load,etc.It has been proved that the pile foundation can obviously improve the sedimitation of the upper structure,and also can greatly enhance the ability against overturning of the upper structure.Pile foundation has a good performance against the earthquake. When earthquake occurs,the interaction between pile and soil can lengthen the natural cycle of the building so that it could reduce the horizontal reaction of the structure. Under the action of the earthquake,in the process of the interaction between the upper structure and building foundation,the friction resistance produced by the pile foundation and the foundation can absorb a part of seismic energy,so that it can reduce the destructive power to the upper structure,and play a role in isolation.The observation and investigation on the earthquake damage shows that the damage of the pile foundation was mainly due to the effect caused by the great movement of the foundation or the inertia force of the upper structure.Common failure forms are bending,shear and crack damage.They often happen near the top pile,soft soil or pile cap,and some are caused by great deformation.The concealment of the destruction makes it extremely difficult and quite expensive to repair the damaged piles,so it has important academic significance and practical value to do the numerical simulation study on the interaction among the pile-soil-upper structure. Under the earthquake.Through analysising modeling ,this paper mainly expounds the displacement and internal force regularity of the pile-soil-upper structure,and puts forward some advise on the ruture design.The details of the research and achievements are as follow:(1) Making sure the on the basis of summarizing the theory of elastic-plastic and anlysising the advantages and disadvantages of the constitutive model, constitutive relation(2) Using a programme that adopts power interaction finite element method analysis on stake-ground-upper structure system,including the solution to the nonlinear dynamic equation,element selection, Simulation method of soil boundary,and the imput of the ground motion(3) Analyzing the change of the superstructure stiffness effect on the pile's seismic behavior ,and the change increases the qulity of interaction system of the pile-soil-upper structure,so that on the same earthquake loading,the inertia force increases,resulting the dynamic response of the lower pile foundation.increases.(4) Adopting substructure technique to calculate and analyze parts of problems on the dynamic characteristics of the structure- pile foundation system.