Experimental and Numerical Assessment on the Crashworthiness of Duct-type Reinforced Concrete Structures for Submarine Cable Protection under Anchor Drop Impacts

ABSTRACT This study evaluates the crashworthiness of a Duct-type Reinforced Concrete Structure (DRCS) for protecting submarine cables against stock anchor drop impacts, utilizing both full-scale testing and numerical analysis. A full-scale test with a 1.27-ton anchor dropped from an equivalent height of 1.5 m was conducted to obtain strain histories and damage patterns. To establish a reliable numerical methodology, Coupled Euler-Lagrange (CEL)-based Fluid-Structure Interaction (FSI) simulations were performed. Four concrete constitutive models—ISO, WCM, RHT, and CSCM—were critically compared to identify the most suitable model for reproducing experimental results. The comparison revealed that the Continuous Surface Cap Model (CSCM) demonstrated the highest accuracy, with an average strain error of approximately 14% and a standard deviation of error ratio of 0.02, effectively capturing the strain rate effects and local damage behavior observed in the test. The validated numerical model exhibited an average error range of 14–27% across key crashworthiness indicators, which is within the acceptable range for concrete dynamics. The findings confirm that the proposed numerical approach using the CSCM model provides a robust framework for the safety design and assessment of submarine cable protection structures.