Experimental study on a debris-flow drainage channel with different types of energy dissipation baffles

Debris-flow deceleration baffles can effectively reduce debris-flow velocity and hence reduce the impact of flowing debris on architectural structures in mountainous areas. In this study, baffles with three different shapes were developed to investigate the velocity reduction effect and energy dissipation characteristics in a 6-m-long flume. The influences of debris-flow density, baffle shape, and row spacing were investigated. The debris-flow velocity was measured to calculate the velocity reduction ratio, which was influenced by the above variables. Experimental results reveal that the arrangement consisting of three rows of staggered baffles can reduce the velocity by 27.30%-39.32% compared to velocity reduction ratio of the controlled trials, wherein the flume bottom is empty. The velocity reduction ratio increases with an increase in the density; increasing the density from 1200 to 2100 kg/m3 can lead to a 20% increase in the velocity reduction ratio. The velocity reduction ratio is not proportional to the equivalent area of impact, and the maximum velocity reduction ratios for the cubic, trapezoidal, and triangular-prism-shaped baffles are 25.0%, 26.3%, and 23.5%, respectively, at the channel slope is 12°. Furthermore, the velocity reduction ratio is inversely proportional to the spacing between adjacent rows. Increasing the row spacing from 0.10 to 0.25 m leads to a 22% decrease in the average velocity reduction ratio. The maximum average velocity reduction ratio reaches around 25%, when the row spacing reduces to zero, and the baffles lose their deceleration ability when the row spacing increases to 1.42 m and the velocity reduction ratio is − 13%. These experimental results can provide useful references for the design of large gradient drainage channels.