Abstract: Landslide-debris flows are characterized by high speed, long travel distance, and high energy, making them highly destructive. Their movement process and deposition patterns are significantly influenced by terrain undulations, but existing studies still lack sufficient understanding of how these factors regulate the kinetic mechanisms. This study systematically conducted 28 sets of debris flow experiments with different volumes (6.76×103−2.50×104 cm3) and particle sizes (0.4−3.0 cm) using a chute physical model, setting three types of terrain obstacle heights: 8 cm, 15 cm, and 25 cm. These experiments provides a theoretical basis for analyzing debris flow disaster mechanisms in complex terrain. The experiments show that low terrain undulations of 8 cm can trigger particle ejection and secondary acceleration, but with significant fluctuations, while high terrain undulations of 25 cm retain particles, increasing the energy dissipation rate to 91%−96% and significantly inhibiting motion. As particle volume increases, the initial kinetic energy is enhanced, but increased internal friction reduces particle mobility. Larger particle sizes reduce frictional energy loss and enhance fluidity, extending the flow range, and due to their specific flow characteristics, large particles are more influenced by terrain undulations. Analysis of Froude numbers (Fr<0.8) and centroid displacement indicates that the debris flow is in a slow flow state, and terrain undulations dominate energy distribution through the interplay of inertial force and resistance. This study quantitatively reveals the synergistic regulation mechanism of terrain–particle–volume, providing a theoretical basis for risk prediction of debris flow disasters in high mountain canyon areas.

Key words: landslide-debris flows, movement process, deposition patterns, terrain undulation, chute experiment