Impact Analysis of Hazardous Chemical Explosions on Underpass Tunnels From Ships in Navigation Channels

Hazardous chemical leakage and explosions on navigation vessels pose severe threats to underlying underwater tunnel structures. This study adopts the TNO multi‐energy method to determine the overpressure, duration, and effective radius of blast loads induced by vessel‐based chemical explosions. Combined with numerical simulations, the dynamic structural response of underwater tunnels and the displacement characteristics of saturated riverbed soils under blast impact are systematically investigated. The results show that the blast shock wave exhibits negligible differences in propagation velocity and pressure attenuation rate within saturated riverbed soils. For a fixed sum of water depth and tunnel burial depth, varying water depths induce highly similar tunnel dynamic responses and consistent blast load attenuation laws in water–soil media. The shock wave pressure attenuates slowly in the upper water layer, decays rapidly within 5 m below the riverbed surface, and presents a slower attenuation rate after entering riverbed soils. In contrast, when the total depth is variable, the maximum tunnel displacement and peak overpressure on the tunnel upper surface demonstrate a significant linear correlation with the total depth.