Numerical Calculation Study On Seismic Response Of Underground Subway Structures

With the development of cities, various of underground structures such as subways are constructed. The seismic design and safety evaluation for these structures become key subjects. An finite element model for soil-structure dynamic interaction is presented based on the theory of seismic design. Seismic responses of subway tunnel's lining structure and station structure are analyzed systematically, including factors which influent it.The main contents of this paper are described as follows:1. Some key problems including the method of numerical integration, damping model, soil's constitutive, boundary conditions, and how to select seismic waves are discussed. The dynamical model is established based on these discussions.2. The seismic responses including displacements and internal forces are calculated under the different waves. Results indicate that there are differences between the bi-directional seismic loading and the unidirectional seismic loading. The obvious difference is that the internal force got in the former condition is larger than that in the latter condition, and vertical seismic effects on structures should not be ignored.3. The underground structure is affected by the surrounding soil, and while the deformation of soil is applied on the structure, the obvious displacement and internal force of the structure occur. The performance shows that it is not sensible to hope structure to resist all the deformation of the surrounding soil, increase the flexibility and ductility of the structure can improve the seismic behavior.4. The calculation shows that the column of the subway station is the weak part of loading, then the column's strength and ductility should be improved in design.5. Responses of different soils indicate that the weak surrounding rock is unfavorable for the structure to resist the seismic while the steady rock does oppositely.