Dynamic Response Analysis Of Subway Station Structure Under Far-field Ground Motion

With the continuous expansion of urban development scale,the problem of traffic congestion is becoming more and more serious.The subway has gradually become one of the most important modes of urban transport.If the subway is in a weak site,once encountered far-field ground motion,it will exacerbate the damage to the underground structure.For the seismic research of the subway,there is a gap between China and the developed countries.The study of seismic response analysis of underground structures under far field seismic excitation is not deep enough.Therefore,the dynamic response analysis of subway station structure under far field ground motion is of great significance to the design of underground engineering in soft foundation.This article is based on a practical project in Suzhou area and based on ABAQUS finite element analysis platform,and establish three-dimensional numerical model of soil-station dynamic interaction in deep and weak foundations.The dynamic response of Tekirdag wave and Izmit wave with different probability of surpassing probability is studied,which can provide reference for seismic optimization of subway underground station structure in similar sites.The main contents and conclusions of this paper are as follows:1.Based on the basic theory of dynamic finite element,take into account the accuracy of the material constitutive model and the effectiveness of the introduction of damping.The ABAQUS is developed twice in Python,self-prepared viscoelastic boundary automatic application procedures.The effective fluctuation input of far field ground motion is realized,to ensure the stability of the results of the operation and reliability.2.Reasonable selection of the calculation range and unit size and for deep soft site conditions,respectively,establish of a free space and a three-dimensional model of the station site.Compare the modal analysis results of the two models,and the effects of different loading waveforms on the dynamic response of the model are studied.It can be found,the vibration of the structure is basically consistent with the vibration of the surrounding soil,and the response of the station structure is mainly controlled by the deformation of the foundation soil.Due to the near and far field spectral characteristics are different,the frequency of the far field is close to the fundamental frequency of the shallow surface of the free surface and the amplification effect of free field under far field wave is more obvious than that of near field.The presence of station structure significantly affects the ground motion characteristics of the surrounding soil.3.Considering the far field seismic wave input with different transcendental probability,the dynamic response of soil-station system is studied from the aspects of acceleration,deformation and internal force.The acceleration and fourier changes of soil layers are analyzed,and the relative horizontal displacement of the station structure and thestress distribution of the structure are analyzed.Seismic waves in the process of propagation,show a low-frequency from bottom to top,high frequency reduction phenomenon.The seismic response of the model is synchronized with the intensity of the seismic stimulus,and the seismic response decreases with increasing depth.But the low-frequency amplification effect of the soil on the far-field wave is reduced with the increase of the seismic wave PGA.4.By changing the station stiffness,density and surrounding soil strength,the factors influencing the seismic response of the station are studied from the aspects of structural displacement and stress.Soil characteristics are the key factors influencing the dynamic response of station structure,and the station itself is a material change in the nature of the whole model is small.