Effects of Baffle Transverse Blockage on Landslide Debris Impedance

Mitigation of landslide debris hazards sometimes requires the use of structural countermeasures such as baffles to minimise the destructive impact energy of a torrent. An array of baffles is a type of structure countermeasure frequently installed along the flow path to protect downstream facilities. They are currently designed using empirical methods since their interaction mechanism with landslide debris is not well understood. In this study, a 5 m long rectangular flume model is used to conduct experiments to investigate flow interaction between baffles and uniform dry sand. Dynamic similarity between model and prototype flows is achieved by adopting Froude scaling. The discrete element method (DEM) is then adopted to conduct numerical back-analysis of flume experiments to study the effect of varying transverse blockage on flow impedance. Results reveal that higher degrees of transverse blockages are more effective at developing upstream subcritical conditions which may develop into a granular jump and promote additional energy dissipation. An increase in the degree of transverse blockage from 20% to 37% provides up to 18% additional kinetic energy dissipation.