Analysis Of Seismic Response Of Underground Subway Structures

With the rapid growth of urban population in recent years, urban traffic congestion problems become more and more serious, and subway is one of the most important ways to solve urban traffic problems. However, many earthquake disasters indicate that underground subway structures are not as safe as people think, and can also damage and collapse under dynamic loadings such as earthquake damage, et al. Therefore, it has very important significance on the seismic design of underground structures such as subway to study the dynamic contact problems of soil-underground structure, the dynamic viscous-spring artificial boundary, the baseline drift and its implementation in the finite element method, and to analyze the seismic response of underground structures with the combination of the numerical seisimic simulations of the underground structure of Dakai subway station and of certain tunnel section of Hangzhou Metro Subway Line # 1 in soft soils.Based on the previous studies, this thesis investigates the seismic response of Dakai subway station and certain tunnel section of Hangzhou Metro Subway Line # 1 using three dimensional finite element ADINA software and the main contents are as follows:(1) With the development of finite element method and the computer technology, the whole process numerical simulation of the contact using computers can be achieved, which provide a powerful tool to analyze the soil-structure dynamic nonlinear interactions. This thesis introduces the basic theory and applications of the numerical method of the dynamic contact.(2) At present, the dynamic viscous-spring artificial boundary is one of the most applied local artificial boundaries, which can absorb the wave energy propagated to the artificial boundary and the dispersion of the reflected wave so as to eliminate the reflected energy. As the dynamic viscous-spring artificial boundary is easy to implement in the finite element program, this thesis investigates how to implement the viscous-spring dynamic artificial boundaries of seismic waves input in software ADINA, and verify its reliability with the input of the displacement of seismic waves and velocity time history.(3) It usually has some long-period components in the acceleration records, where the velocity and displacement time history can cause serious drift if integrated. Therefore, the second chapter of this thesis also studies the drift theory and the method of correcting baseline drift.(4) Considering the contact between soil and structure, the finite element model of Daikai subway station is established to study the soil-structure interaction mechanism, load transfer mechanism and the structure failure mechanism itself under seism, where the rational explanations are provided for the main damage of Daikai subway station. Meanwhile, the examples also verify reliability of nonlinear dynamic interaction model and numerical method of the soil-underground structure this thesis established.(5) Finally, this thesis analyzes the seismic response of the Hangzhou Metro tunnel, summarizes the subway seismic response of the subway underground structures, and provides the calculation results of the tunnel seismic response and the change law of the deformation and force of the tunnel lining, which can have certain valuable reference for the seismic design of subway tunnels in soft soils.