Dynamic Response Analysis Of High-cap Group Piles Under Horizontal Seismic Load

With the development of cross-sea bridges,port projects,coastal projects and other projects,the application of high-cap pile group foundations has become more and more extensive.At the same time,earthquake is a natural disaster that is inevitable and will cause huge losses to human production and life.Therefore,it is necessary to carry out relevant seismic research and analysis on the foundation of large-scale projects—high-cap pile group foundations.so that it could provide reference suggestions resist earthquakes to structures in actual projects.In this paper,the numerical simulation method will be used to establish the model using the large-scale finite element software ABAQUS.And at the same time,considering the actual soil layering phenomenon,the dynamic response analysis of the high-cap pile group foundation under the horizontal seismic load will be carried out.The main work and research conclusions of the thesis are as follows:(1)Use python for secondary development,by modifying the ABAQUS input file,effectively realize the input of viscoelastic artificial boundary and horizontal seismic force in the three-dimensional model.The feasibility and accuracy of the method are verified by numerical modeling and analysis of existing physical test models.(2)Combining actual engineering,adopt Morh-Coulomb constitutive model,consider the interaction of pile and soil,establish a three-dimensional numerical model,and study the horizontal displacement and acceleration of the pile cap surface under horizontal seismic force with time.Trend,the variation law of the horizontal displacement of the pile top and the internal force with time,and the distribution characteristics of the pile displacement,acceleration,pile side friction and pile side soil pressure along the pile body.(3)Through the control variable method,the influencing factors such as the frequency spectrum of the seismic wave,the peak value of the seismic wave acceleration,the free length of the pile,the spacing between the piles,etc.are sequentially changed,and the dynamic response of the pile cap,the internal force of the pile top,the side friction resistance of the pile and the change law of the earth pressure are analyzed.The study found that the change of seismic wave frequency spectrum has obvious influence on pile top internal force and pile side friction resistance.Secondly,the dynamic response of the pile foundation,such as the dynamic response of the pile cap,the internal force of the pile top and the pile side friction resistance,increases with the increase of the seismic wave intensity.The free length of the pile is an important factor affecting the seismic performance of the structure.The dynamics of the pile cap and the internal force of the pile top of the high-cap pile group foundation increase with the change of the free length of the pile.With the increase of pile spacing,the influence of pile group effect of pile group foundation is gradually reduced,and the bearing capacity of each pile is fully utilized.Numerical simulation results show that applying viscoelastic artificial boundaries to the 3D model can effectively improve the accuracy of the simulation results,and the horizontal seismic force input method based on wave theory is feasible and effective.The conclusion of numerical model analysis can provide reference basis for actual engineering.