Seismic Response Analysis Of Railway Bridge Soil Pile Foundation System In Near Fault Environment

With the acceleration of railway construction in China,railway bridges are inevitably close to or even cross fault zones,which is easily affected by near fault ground motion.At the same time,for railway bridges crossing soft soil areas,pile-soil interaction is an important factor that can not be ignored to affect their dynamic characteristics.However,the existing studies are too simple to consider pile-soil interaction,and rarely consider soil The influence of body nonlinearity and contact nonlinearity on superstructure.In this paper,the continuous beam bridge in the Wuhan-Guangzhou passenger dedicated line(48m+80m+48m)is taken as the research object,and the dynamic response of the "bridge-soil-pile foundation system" under near-fault ground motion and railway train load is analyzed and studied..This article mainly completed the following research work.(1)Under the excitation of train and track irregularity,select appropriate ground motion parameters,based on ANSYS finite element analysis software,establish two kinds of nonlinear bridge structure finite element model considering pile-soil interaction(dynamic p-y curve method)and not considering pile-soil interaction(pier bottom consolidation),and carry out natural vibration analysis.Use xtract software to calculate the bending moment and curvature of pier and pile section The elastic-plastic response of bridge structure under lateral and vertical seismic loads is analyzed,and the seismic response of bridge structure by p-y method and m method is compared,and some meaningful conclusions are obtained.(2)In the comparative analysis,the dynamic response of the bridge structure under pile-soil and pile-soil models under vehicle-only,earthquake-only,and vehicle-seismic loads is also considered.The research shows that under the action of earthquake load,if the pile-soil interaction is not considered,the displacement of the railway bridge is small,which is not consistent with the actual situation,and has adverse effect on the design of the bridge;in addition,the effect of vehicle crossing the bridge and earthquake force exists But it is not exactly equal to the displacement response of the vehicle bridge system under the action of seismic force.At the same time,the middle span displacement of the bridge is greater than the middle span displacement of the side span,and the top displacement of the middle pier is greater than the top displacement of the side pier.(3)Based on the whole bridge model of railway train continuous beam bridge,using near fault ground motion and track system as the main excitation,the seismic response of vehicle bridge system to different vehicle speed(with or without earthquake action),vertical ground motion effect(V/H and AC/VV),soil parameter(friction angle of sandy soil and undrained shear strength of cohesive soil)is analyzed by using nonlinear time history analysis method Influence.