The effect of check dams on the dynamic and bed entrainment processes of debris flows

摘要

Bed entrainment plays a significant role in the formational process of a debris flow. Thus the influence of bed entrainment may be an important factor which cannot be neglected when assessing the prevention effect of check dams. However, since few studies have investigated the interaction between check dams and debris flows with considering bed entrainment, the interactive effect of check dams on the dynamic and bed entrainment processes of debris flows remains unclear. Therefore, in this paper, an improved depth-averaged model is proposed to overcome this weakness. In the improved model, the impeding effect of a check dam is simplified as a rigid constraint, and a new computational scheme is adopted to improve the simulation efficiency. Using this model, the dynamic and bed entrainment processes of the catastrophic 2010 Hongchun gully debris flow are analyzed, and the effects of check dams on this debris flow are studied. The results show that the present model can properly depict the dynamic and bed entrainment processes of the Hongchun gully debris flow. Without bed entrainment, the flow quantity tends to decrease gradually from the upstream to the downstream, while the flow quantity will show an opposite tendency if bed entrainment is considered. The check dams can largely reduce the bed entrainment scale and flow quantity of this debris flow. Additionally, the prevention effect of check dams tends to be better when they are constructed at the upper part of the gully by constraining bed entrainment.