Blast resisting responses and upgrading technology for an underground structure subjected to external explosions

Underground structures are widely constructed as the key parts of lifeline system with synthetic functions in modern society. Simultaneously, the integration of blast-resisting infrastructures and civil underground structures has attracted increasing attention. Therefore, this study investigated the blast-resisting mechanism of underground structures under conditions of surface and subsurface explosion. Then, a series of upgrading approaches for underground structures subjected to external explosion are compared and investigated through the isolation technology, Strain-Hardening Cementitious Composites (SHCC) technology, and partially encased composite structures technology. The obtained results showed that the developed blast-resisting evaluation framework can effectively quantify the multi-performance of the entire underground structure subjected to the external explosions, given the formation of an evaluation database of comparative performances between variant explosion cases to distinguish the component vulnerable to blast locations. Dealing with any possible top-surface explosion and penetrating blast, the proposed isolated column, SHCC column, and partially encased composite column-based methods can effectively protect the vulnerable column, at the same time reducing the dynamic responses near the explosion center. Considering the stochastic property of the explosion, the integration upgrading approach using the SHCC isolated column is suggested for the underground structure subjected to both explosion and earthquake in practice.