Nonlinear Seismic Response Analysis Of Underground Structures

The seismic analysis of subway structure has great significance to the development of the seismic design and practice of underground structure. This paper presents seismic response analysis of metro tunnels and station under thick soil layers,which based on the Soil-Structure interaction program FLUSH. In the nonlinear model, a equivalent linear method is used, considering the linearity of concrete. The accuracy was verified by comparing with the results of viscous-spring boundary. After that, a case study is conducted with metro station under thick soil layers in Tianjin city based on the Response Displacement Method, in which both linear and nonlinear method is used. The regulars were summarized through comparisons with Time history analysis method, and the differences are compared between the two methods.Research shows that, in the linear analysis, stress of the double tunnel closed to each other can be increased by up to 49.1% compared with the single tunnel. And in the nonlinear analysis, it can be increased by up to 45.3%. The results got from the Response Displacement Method is less then that of Time history analysis method.When calculating the single station, the error value of the the Response Displacement Method can be reached at 33.4%. And when calculating the double station, it can be26.7% in linear analysis, and 39.8% at in nonlinear analysis.