The initiation mechanism of gravel-type debris flow based on laboratory simulation experiments.

Debris flow is a geological process primarily triggered by factors such as rainfall or earthquakes, characterized by strong abruptness and significant destructive force. It poses a severe threat to human life and property. Exploring its formation, initiation mechanisms, and effective early warning measures is a reliable approach for disaster prevention and mitigation in mountainous regions. An indoor simulation experiment system was designed to study the initiation process of coarse-grained gravel-type debris flow under different particle sizes and slope angles. The interplay among the mean particle size, water flow, the slope angle of the material source, and the onset of debris flow has been elucidated to assess the dynamic changes in various characteristic parameters. This analysis formed initiation criteria specific to gravel-type debris flow. The combined particle size and slope angle of the material source were positively correlated with the water power required for debris flow initiation. A fitting relationship between the unit width flow rate, mean particle size, and slope angle was established. The humidity, seepage pressure, soil pressure, slope angle, and vibratory shock acceleration of the material source had characteristics such as mutability or asynchronism during the formation and initiation of debris flow. However, humidity and seepage pressure were not used as initiation criteria. The initiation criteria for debris flow included changes in characteristic parameters (e.g., soil pressure, slope angle, and vibration acceleration). The research findings can provide a reference for the characteristic identification and initiation early warning of similar types of debris flows, enhancing the safety management level of debris flow disasters.