Impact mechanisms of granular flow against curved barriers

Abstract

Curved seawalls remain one of the most widely adopted coastal-protection measure. A curved face redirects flow momentum and prevents waves from overtopping. Likewise, the use of curvatures for landslide barriers merits investigation given their potential engineering value in reducing the runup height and impact force of geophysical flows. In this study, flume tests were carried out to explore the impact mechanism of dry granular flow against a curved barrier. The impact force, runup height and regime transition path of granular flow for both vertical and curved barriers were compared under different Froude conditions (Fr = 4·7 and 6·4). The results reveal that in comparison to a vertical barrier, curved barriers reduce the runup height and elongate the duration of impact by up to 17 and 15%, respectively. For curved barriers, the impact force is reduced by up to 25% for coarser granular flows. By contrast, the impact force does not exhibit a significant reduction for finer granular flows. Furthermore, results demonstrate that curved barriers are most suitable for reducing the impact force and suppressing the runup height for more inertial flows, specifically Fr > 6·4 in this study. The phase diagram suggests the curved barrier prompts the transition from airborne jet regime to dead zone regime. The results demonstrate that curved barriers show promising engineering value for mitigating geophysical flows.