Experimental study on a debris flow water-sediment separation structure of a funnel-type grating and its sorting characteristics

Debris flow control structures based on water-sediment separation have been widely used in engineering practice; however, most existing water-sediment separation structures are unable to continuously achieve the water-sediment separation function. To realize the sustainability of the water-sediment separation function of the structure, a new debris flow water-sediment separation structure combining a horizontal grating structure with a vertical flexible structure (flexible barriers) is proposed in this paper. The water-sediment separation effect of the structure and the regulation effect of the structure on the performance of the debris flow are evaluated through flume tests. The results reveal that the structure has a good water-sediment separation capacity and can continuously perform the water-sediment separation function. After structural regulation, more than 30% of the solid particles in the debris flow are separated out, the density is reduced by at least 10%, the average particle size of solid particles can be reduced by approximately 40%, and the flow velocity is reduced by more than 20%. The scale, density, and velocity of the debris flow are reduced after the structure is regulated, and the debris flow can be effectively regulated in terms of material and energy. The structure exhibits a good sorting effect on debris flows with a density of ≤ 1800 kg/m³. The proposed new structure could provide a new idea for debris flow prevention and mitigation technology.