Seismic Response Analysis Of Soil-pillarless Large-span Metro Station Structure

The pillarless large-span metro station has the advantages of being able to provide more open space and convenient passenger circulation,and has gradually become one of the main forms of subway station structure.However,there are few studies on the seismic behavior of soil-structure interactions for this structural form.In this paper,the Jinqiao Station of Nanning Metro Line 5 is used as the engineering background,and the seismic performance of the pillarless large-span metro station is studied by the combination of simulated seismic shaking table tests and finite element numerical analysis.The main research contents and results are as follows:(1)Taking the Jinqiao Station of Nanning Metro Line 5 as the engineering background,according to the Bockingham π theorem,the structure of the prototype metro station was simulated by using the material of microconcrete,and the hardness ratio of the soil was reduced by adding the sawdust to the soil,then the dynamic triaxial test of the test soil was carried out.With the excellent cycle similarity as the control index,the reasonable ratio of the test soil is determined,which makes the model soil consistent with the time similarity of the model structure.A reasonable test box was selected,and a shaking table test model considering the interaction of soil-metro station structure with a similar size ratio of 1/50 was designed.The measured results show that the experimental model can better reflect the dynamic characteristics of the actual project.(2)El Centro wave and Wenchuan Wudu wave were selected and the Nanning artificial wave was fitted.The simulated seismic shaking table test of the experimental model under various working conditions such as horizontal earthquake and vertical earthquake was carried out,and the seismic response law of a pillarless metro station considering soil-structure interaction was studied.The results show that the acceleration response of the model soil increases with the decrease of the buried depth under the action of horizontal and vertical earthquakes.Under the horizontal earthquake,the peak acceleration response of the model structure is the smallest at the bottom plate,and the middle plate is second,and the peak acceleration response of the top plate is the largest.Under the vertical earthquake,the peak acceleration response of the structural bottom plate is greater than the peak acceleration response of the middle plate.The structure’s own mass and stiffness distribution and soil action are important factors influencing the seismic response of the structure.(3)Applying ABAQUS general finite element software,through the compression test and direct shear test of the model soil,the relevant parameters of the soil were determined.The reasonable soil and concrete constitutive model were selected and the soil-structure contact treatment method was determined.Based on the shaking table test model,the finite element numerical calculation model of the soil-pillarless large-span metro station was established.The finite element numerical analysis under various working conditions was carried out and compared with the shaking table test results.The results show that the finite element numerical results agree well with the shaking table test results,indicating that the finite element calculation model and calculation results are reliable and effective.In addition,in order to consider the influence of spatial seismic action on the model structure,the finite element analysis of the horizontal and vertical seismic coupling was also carried out.The analysis results show that the coupled seismic action has less influence on the horizontal displacement response of the station structure model than the horizontal seismic action,and has a larger amplification effect on the horizontal acceleration response and stress response of the station structure model.Under normal circumstances,the horizontal acceleration of the floor can increase by up to 44.5%,the side wall stress increase can reach up to 82.0%,and the stress increase in the plate can reach up to 288.9%,which should attract the attention of researchers.The research results in this paper can be used as reference for seismic performance research and engineering application of pillarless large-span metro stations.