Abstract:The drainage channel plays a key role in the mitigation of debris flow. However, the traditional drainage channels are difficult to consider the problem of debris flow management in a large slope gully occurred in recent years. Therefore, a type of “step + baffle” drainage channel was proposed to deal with this question. Three geometric shapes of baffles (square, triangle, and trapezoid) were designed to test their performances for regulating the flow patterns, flow density and depth, grain size, velocity, and impact pressure based on the flume experiments. The results showed that the debris flow was lifted into the air by the baffles, and a wavy flow pattern generated in the drainage channel. Although the amplification effect on the flow depth was produced by the baffles, it can significantly reduce the debris flow velocity. The amplification effect of the square baffles was the most obvious, and the trapezoidal baffles had the weakest amplification effect. After the regulation of “step + baffle” systems, the density of debris flow and the particle size of solid phase at the exit decreased, and the trapezoidal baffle showed the strongest ability of blocking coarse and discharging fine. The impact pressure on the trapezoidal baffles was larger than that on triangular baffles. The first baffle of square baffle drainage channel endured the largest impact pressure of debris flow. The impact pressures on the second and third baffles in trapezoidal baffle drainage channel were both the largest among the three types of drainage channels.