Seismic Response Analysis Of Pile-supported Continuous Bridge On Liquefiable Lateral Spreading Gournd

Based on the seismic damage investigation,the lateral spreading of liquefiable soil is one of the most destructive influence resulting in the failure of pile and superstructure.The existing research on seismic response of bridges usually adopts the assumption of rigid foundation or alternatively taking the soil as elastic,which couldn't consider the effect of the interaction between soil and pile neither the dynamic pile-soil-superstructure interaction when lateral spreading happens.Hence,this paper established a simplified method for analyzing soil-pile seismic interaction in lateral spreading ground,and used this method to build a three-dimensional seismic response analysis model of pile-supported continuous bridge in lateral spreading ground.The seismic response characteristics of the soil-pile-continuous beam bridge in the liquefaction-induced lateral spreading field are analyzed considering the pile-soil-structure dynamic interaction,and the influence of different ground motion characteristics on the seismic response of continuous bridge with pile foundation is studied by using the method of calculating random variables.This paper puts forward some suggestions for improving the seismic design method of bridge in China.The main research work and some understandings obtained in this paper are as follows:(1)Nine-node-four-quad fluid-solid coupling element and multi-yield elastic-plastic constitutive model are used to simulate soil,beam-column element is used to simulate pile,combined with appropriate definition of the p-y curve,the simplified analysis method of soil-pile seismic interaction in liquefaction-induced lateral spreading field is established.And the correctness and reliability of the simplified analysis method are verified by the test results of centrifuge vibration table.(2)The superstructures such as deck,pier and abutment are modeled,and with the proposed simplified analysis method of soil-pile seismic interaction,a 3D seismic response analysis model of pile-soil-bridge system is constructed.The seismic response characteristics of pile-supported continuous bridge in liquefaction-induced lateral spreading field are analyzed,finding that the response of pile supported bridge located in lateral spreading field is significantly different from that in normal liquefaction field.(3)The correlation between seismic response of pile-supported continuous bridge in lateral spreading field and different ground motion characteristic parameters is analyzed by calculating the response of pile-soil-bridge system in a seismic combination.The influence of earthquake characteristic parameters on these responses is further studied by calculating random variables.It is found that the peak bending moment and peak displacement of the bridge are significantly correlated with some ground motion characteristic parameters,residual deformation is affected by multiple factors and once the liquefaction-induced lateral spreading occurs,the duration of the ground motion will have little impact on the response of the bridge.