Discrete element modeling of rock-filled gabions under successive boulder impacts

Abstract

A discrete element model consisting of irregular crushable filling particles and a flexible wire mesh is established. The numerical model is validated against the static net punching test and the dynamic pendulum impact test to ensure that the large irreversible plastic deformations and the impact forces during successive impacts can be captured. The impact force reduces at small friction coefficients, which is associated with the significant particle rearrangement during the impact process. The important role of friction is further confirmed by the energy evolution, showing that friction is the dominant mechanism for energy dissipation, instead of the more intuitionistic collision or particle crushing. Besides, the increase of impact force with the number of impacts becomes more significant at a higher impact energy due to the faster rate of momentum exchange. A bounce-back behavior of the boulder is observed when the impact energy is low, which may attenuate the impact force like the reflection waves in real debris flow events where multiple boulders are present. Our results highlight the combined effects of contact properties and impact energy, which are valuable in the design of rigid barriers shielded by rock-filled gabions for hazard mitigation in engineering practice.