Developing Tsunami-Resilient Rubble Mound Breakwater: Novel Gabion-Based Technique

Abstract

The rubble mound (RM) breakwater, which is a prevalent coastal structure worldwide, often faces the significant challenge of tsunami-induced damage. Coastal regions which are characterized by high population density necessitate robust breakwaters to withstand the destructive forces of tsunamis. The most devastating natural hazard that a breakwater could encounter during its lifespan is the tsunami. Past occurrences have revealed vulnerabilities in conventional RM breakwaters leading to failures attributed to the scouring of rubble and seabed caused by excessive seepage during tsunami overflow events. This study presents novel countermeasures aimed at mitigating the potential failure mechanisms induced by tsunamis on RM breakwaters. The proposed countermeasure elements include gabions, crown walls equipped with shear keys, and sheet piles. To assess the efficacy of these innovations, a series of tsunami overflow tests was conducted on small-scale models. The results demonstrated a marked improvement in the stability and resilience of RM breakwaters against tsunamis with the incorporation of these countermeasures. Additionally, numerical simulations were performed to determine the precise mechanisms influencing the behavior of the breakwater during tsunamis. This study introduces innovative techniques for enhancing the resilience of rubble mound breakwaters against tsunamis, which have significant implications for coastal protection and disaster mitigation efforts worldwide. By incorporating gabion-based countermeasures such as wire cages filled with rocks (gabions), crown walls with shear keys, and sheet piles, substantial improvements were observed in the stability and durability of rubble mound breakwaters during tsunami events. The proposed technique enabled the rubble mound breakwater to withstand Level 1 tsunamis without undergoing any deformations. For coastal communities facing the threat of tsunamis, implementing the proposed novel gabion-based techniques offers tangible benefits in terms of enhanced protection against catastrophic tsunamis. The proposed technique provides cost-effective and adaptable solutions to existing and newly constructed rubble mound breakwaters. Through practical application of the proposed technique, coastal engineers, policymakers, and disaster management agencies can effectively mitigate the risks posed by tsunamis.