An Experimental Investigation into the Use of Three-Stepped Gabion Walls for Coastal Protection Works Using Acoustic Doppler Velocimeter

The paper presents a detailed study and analysis of the hydrodynamics of aggregates-filled gabion models for coastal protection works. These walls are constructed along coastal fronts to protect the beaches from the heavy impact of ocean waves and soil erosion at the base of other coastal protection structures. The high hydrodynamic energy of ocean waves can easily bypass the sand and cause destruction. Stepped gabions are used in coastal areas as effective energy-dissipating structures by reducing the impact of waves. Gabion walls are typically checked for their stability, structural deformation and erosion from the base. Hydrodynamic forces are rarely used in the geotechnical engineering design, due to their inherent complexities in the measurement when seepage through the pores in between the gabion walls. The experiments in this series aim to examine the behaviour of velocity profiles of waves striking the gabion models placed in a hydraulic flume. The study utilised three-stepped gabion models that is, rectangular gabions with gabion mattress and curved gabions. Acoustic Doppler velocimeter (ADV) was used to determine the velocity profiles at both upstream and downstream sections of the models. These profiles were recorded under different wave conditions, including no waves, waves with frequencies of 0.5 Hz, 0.75 Hz, and 1 Hz. The results indicate that rectangular gabion with gabion mattress and curved gabions with front-facing steps demonstrate superior energy dissipation properties.