Effects of Particle Size and Cushioning Thickness on the Performance of Gabions against Boulder Impact

Gabion is one of the most commonly used cushioning layer to shield protection structures against boulders entrained in debris flow. Despite the prevalence of gabion, its cushioning performance is highly variable because of the wide range of rock sizes and cushioning thickness that are recommended in the literature. Correspondingly, the dynamic response of gabion cushioning layers varies dramatically. In this study, large-scale pendulum impact tests were used to calibrate a discrete element model. Subsequently, a parametric study was carried out to discern the effects of particle size and cushioning thickness on the impact load and transmitted load exerted by a boulder. Results reveal that as the particle size in the cushioning layer decreases, the force chains collapse more easily, and the expansion angle of strain energy increases. To optimize the performance of a gabion cushioning layer, practitioners should reduce the size of the particles to a normalized particle radius of about 0.1. A normalized part...