RECENT ADVANCES IN THE SEISMIC PERFORMANCE AND FRAGILITY EVALUATION OF DOUBLE-BOX TUNNELS

초록

Box tunnels, which are critical components of urban metro systems, are vulnerable to structural damage when subjected to severe earthquake loading. Probabilistic assessment has been widely used to evaluate their seismic performance using the fragility framework. To develop a fragility function, the damage indices correlated to pre-defined set of limit states need to be defined. We review recent advances in characterizing the damage indices from nonlinear models of the double-box tunnels, which range from simplified frame model that only captures flexural damage to the state-of-the-art multi-platform simulation framework and three-dimensional analysis that separately reproduces the concrete skeleton and reinforcement cage. We investigate the simulated damage accumulation patterns validated against the 1995 Daikai station failure case. The damage indices derived for contemporary double box tunnels are presented. Machine learning models are constructed and evaluated to predict the damage states and racking ratio. Lastly, we show a number of fragility curves developed for double-box tunnels based on the newly derived damage indices. © 2024, International Association for Earthquake Engineering. All rights reserved.