Seismic Performance of Uneven Double-Box Tunnel Sections for Subway

The center pillars of the common double box tunnel of subways have been investigated and their seismic performance has been verified in practice by taking advantage of the lesson of collapsed Daikai station in 1995. However, these verified box tunnels are either horizontally-arranged or vertically-arranged box culvert, and the seismic performance of the transition between these box culverts have not yet been examined. In this study, the failure mode of these uneven tunnels and its characteristic shape are analyzed, and the seismic performance regarding the safe internal spaces and the effects of cross-section shape is discussed.