Analysis of Damage Characteristics and Criteria of Independent Embedded Steel Sheet Piles Under Shallow Water Explosion

Independent embedded steel sheet piles, characterized by convenient construction and strong resistance to damage, are widely used in nearshore coastal protection engineering. The damage characteristics of steel sheet piles under shallow water explosions play a decisive role in the reliability of their blast-resistant design. However, existing studies are still insufficient in revealing the damage mechanism of steel sheet piles subjected to shallow-water blast loading. Based on the attenuation law of underwater explosion loads, an engineering calculation model for evaluating blast-induced damage of steel sheet piles in shallow water was established. Meanwhile, a coupled numerical simulation model involving the interaction of multiple materials was developed. Model tests were further conducted to validate the reliability of both the engineering model and numerical simulations. The effects of explosive charge equivalent, stand off distance, and water depth on the damage response of the structure were systematically analyzed. Results indicate that the weak zone of steel sheet piles is mainly concentrated at the water and soil interface, and the dominant failure modes are punching shear fracture and bending deformation. The scaled distance is identified as the key parameter governing damage behavior. When the scaled distance is less than 0.086, punching shear fracture occurs; when it is greater than 1.026, no significant damage is observed; and in the intermediate range, plastic bending deformation develops. Increasing water depth has a limited influence on fracture failure but can significantly extend the bending deformation zone, with an increase of up to 35%. Good agreement is achieved among theoretical calculations, numerical simulations, and experimental results, with relative errors within 10%, satisfying the accuracy requirements for engineering prediction. The findings provide a reliable theoretical basis and practical guidance for blast-resistant design, damage assessment, and protective reinforcement of independent embedded steel sheet pile structures.