|Abstract:The steep-channel debris flow is a kind of special debris flow in Wenchuan earthquake zone, and it is found that has the characteristics of large source quantity, strong erosion and large scale, which is the difficulty of geological disaster management in the earthquake area. This paper taking the Futang gully as the study area, analyze the development condition and characteristics of the steep-channel debris flow, then reappeared and analyzed the starting process of steep-channel debris flow by the means of experiments. The test shows that under the test conditions of the slope of 20°, 25°, 30° and the runoff of 480ml/s, 410ml/s and 360ml/s, the debris flow is starting in different ways (trench bed erosion type, landslide fluidization starting type, Fire pipe starting type). At the same time, combined with the study of the variation characteristics of pore water pressure and volume moisture content in soil during the experiment, the whole process of debris flow starting was restored in detail. The analysis results of the test data show that under different starting modes, the data changes inside the soil show different characteristics: 1, the starting pore water pressure of debris flow under different test conditions shows regular difference, that is, the larger the slope and runoff of the sink, the smaller the driving force required by the debris flow, 2, the larger the slope, the longer the water saturation time required by the soil, and at the same slope, the greater the flow rate, the shorter the pre-water saturation time, 3, the outbreak time of debris flow is inversely proportional to the slope of gully bed, and the larger the runoff, the longer the duration of debris flow. Based on the experimental results, the starting velocity of debris flow calculated by the similarity theory is consistent with the actual situation, which shows that the conclusion of this study can provide reference for the study of the rapid and steep channel debris flow in Wenchuan earthquake area.