| At present, considering the purpose of engineering design and restrictions of the analysis tools, cross-sectional slice type of a typical two-dimensional model is mostly employed on the seismic researches of the subway stations or regional tunnel. But as the development of subway project, subway station structure and form are increasingly tending to large scale, complication and diversification, and more and more space staggered structure have the obvious spatial effect. So, in the actual analysis, the factors should be considered, which are the different texture and structure form, spatial composition and the surrounding site conditions. Therefore, in order to more deeply study on this type of the features and law of underground seismic response and more accurately predict and assess the seismic safety, the three dimensional soil-underground structure dynamic interaction analysis model should be adopted to study on the plastoelastic seismic response of structure. For this reason, the large irregular underground subway station structure of Tianjin rail transfer center has been employed to be the object of study. Considering of soil-structure dynamic interaction, the plastoelastic seismic response on horizontal earthquake has been analyzed, in order to get some meaningful conclusions and provide the useful reference and recommendations on the similar seismic design of underground structures. In addition, this paper also provides the special research and investigation on the FE analysis of soil-structure dynamic interaction. In view of research purposes, basing upon the seismic research of underground structure and soil-structure dynamic interaction, this paper mainly completes the following innovations:(1) The large-scale 3-D nonlinear finite element model including soil, structure of underground station and pile foundation has been successfully built using ANSYS program, based on certain assumptions and reasonable simplification, appropriate parameters selection. Adopting direct dynamic analysis, different seismic waves were inputted to pile-soil-underground station structure model to analyze the plastoelastic seismic time interval response. The calculation result automatically includes the effect of soil-structure dynamic interaction. The structural dynamic responses of the results of every moment are extracted. The results have been analyzed to obtain the structural displacements, accelerations, reaction rules and the lateral deformation feature etc. under different seismic waves with different levels of transcendental probability. Meanwhile, the influence of structural planar and vertical irregularity on its seismic responses was also studied.(2) Although the application study on branching mode-2-step analysis in soil - structure interaction has been more and more mature, the specific application is unusual. In this case, the implementation process and program realization on branching mode - 2-step analysis has been elaborated, and the relevant calculation process and key technology has been explained specially combined with engineering application. From the computational results, branching mode - 2-step analysis method based on ANSYS software soil - structure interaction is feasible and effective.(3) The key issues of building soil-structure dynamic interaction model which is the concern of effective mechanical property of pile-soil homogenization has been specially studied based on the "homogenization" approach. Employing FEM numerical simulation, pile-soil complex element RVE is introduced by referencing composite homogenization theory. The 3-D model is simulated and analyzed by ANSYS, including the simulated compression test and shear test simulation at axis direction. The whole process of RVE (or equivalent) stress-strain curve is obtained through extracting the result combined with the calculation of mechanics of composite materials. Thereby some basic macroscopical nonlinear mechanical properties of RVE is gained. According to these non-linear features, an effective description of the homogenization of the pile-soil mechanical properties can further improved, which makes the result of the soil-structure dynamic interaction model using "homogenization" approach more reasonable.
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