Dynamic Response Analysis Of Urban Large Underground Structure

With the development of the national economy, large amounts of various tunnels and underground structures are increasingly beening built. Their sacle are extending continuously. Underground structures have been utilizing widely in energy sources, traffic, city construction defending engineering, etc. So their importance is more visible. Especially urban underground structures have important effects on urban development and national stability when once earthquake occur. Therefore, anti-seismic of underground structures is important both in theoretical research and engineering.Combined with the Liaoning natural science fund project (20022130), rational numeration model with viscous-elastic artificial boundary condition is proposed according to dynamic FEM. This paper analyzes seismic response of underground structures by ANSYS. By means of signal processing technology, time-frequency analysis and coherence analysis are studied based on MATLAB. The study could be summarized as the following four aspects.(1)Seismic response of subway station with multi-transmitting boundary condition is analyzed by wave approach. Comparison between computational results by ANSYS and the former demonstrates that the former are coincident approximately. And it is verified that the simulation methods in this paper are rational and the model is feasible.(2)Using the unconditionally stable implicit Newmark time intergration algorithm, the effects of some key factors such as buried depth, condition of soil layers and the earthquake excitative orientation are studied.The results show that dynamic response of structure is considerably affected by the thickness of overburden layer, and horizontal slice is more dangerous than upright slice.(3)Considering gravity and contact-nonlinear of soil-structure, seismic response of subway station is taken by means of Full Newton-Rophson. In addition, related problems like influence of structural stiffness, soil properties, contact-nonlinear, earthquake characteristics are discussed in the analysis. Accordingly a series of helpful rule and conclusion are made.(4) The identification of structural damage by figure CWD and time-frequency analysis are made based on MATLAB. Results show that JTFA methods can describe clearly how the spectral content varies with time. CWD is considered to be a perfect quadratic time-frequency analysis method for seismic response signal. The coherence of input signal and response signal and coherence between different location signals are studied, which demonstrate the breakdown mechanism and the vibrational characteristics of structure.