Seismic Responses of a Large Unequal-span Underground Subway Station in Different Classified Sites

Seismic responses of underground structures are severely affected by the site classification, especially for structures with large cross-sectional dimensions.According to the actual engineering construction of Suzhou Metro Line 1, ten different site conditions were designed and divided into common three categories of venues.The nonlinear static and dynamic coupling finite-element model that can simulate the earthquake response among the soil and the complicated unequal-span underground subway station were built.Based on 120 operating conditions, the effects of site classification on seismic responses of underground structures were investigated.As a result, the acceleration amplification of station decreases linearly with site conditions deteriorate from Class Ⅱ site to Class Ⅳ site, and the effects of site classification on earthquake responses of unequal-span subway station are more obvious when the input peak acceleration is small.The peak acceleration magnification coefficient decreases exponentially with the increase of the input seismic intensity, while the horizontal relative displacement increases linearly.Although the subway station in different sites has the same distribution characteristics of tensile damages, the damage degree of the upper cantilever span strengthens obviously with the deterioration of site conditions, especially the site category changes from Class Ⅱ to Class Ⅲ. © 2021, The Editorial Board of Journal of Basic Science and Engineering. All right reserved.