Author(s): Sok An Khe, Sang Deog PARK, Woo Sung Jeon

Linked Author(s): Sok An Khe, Sang Deog PARK

Keywords: Sediment transport; Incipient motion; Sediment bed; Saltation; Drag force;

Abstract: The investigation on the incipient motion of sediment transport is crucial for controlling the stability of the channel bed and banks in responding to the prevention of the hazard to life and infrastructure worldwide. In particular, sediment transport in the mountainous area when there was heavy rainfall. Debris flow frequently occurs and can lead some rocks or boulders from hillslope into the riverbed. This phenomenon could add additional force to sediment transport of riverbed and also affect and change the magnitude of sediment moving. Here we present a study aimed at quantifying the effect of those rocks and boulders on the riverbed. The spheres and natural stone have been used to simulate the rocks and boulders from debris flows moving to the riverbed. In this study, the effects of the falling sphere and natural stone on the gravel bed were investigated for the condition where sediment nearly to the incipient motion condition. Based on the results obtained, the motion of sediment particle under the impact of the falling sphere and natural stone were interpreted using the Shields curve. The size, weight, and shape of the falling sphere and natural stone have significant effects on the movement condition of the sediment bed. In addition, the relationship between drag force and movement length of the sphere and stone was plotted. The saltation trajectories and the frequency of the maximum saltation height, saltation length, and rolling length of the sediment bed were investigated.

DOI: https://doi.org/10.3850/38WC092019-0733

Year: 2019