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<p>Through statistical analysis of pebble dynamics in debris flow heads, this study aims to uncover the underlying mechanisms governing the formation and maintenance of dry heads, which are more destructive than the tails. Laboratorial experiments were conducted using a custom flume with adjustable slopes, and the movement of pebbles was traced through high-speed photography. The two-phase debris flows were concocted by utilizing mixed-size spherical artificial pebbles and incorporating transparent fluids with varying viscosities and rheological properties. Our findings indicate that the debris flows manifest dry-head and hydrated-tail architectures only in scenarios characterized by steep slopes and low fluid viscosity (i.e., slope &gt; 20°, fluidity index &lt; 0.49, and consistency &lt; 0.75). Upon partitioning the heads into saturated, near-bed dry, and air regions, our statistical analysis reveals that the pebbles in the saturated regions can replenish dry heads via both saturated-dry and saturated-air-dry paths. The widely accepted circulation pattern can be considered a case of the dual-path mode. Furthermore, we found that the particle-size segregation is not essential for the formation of dry heads, and the upward coarsening process may occur in the air regions resulting in inverse gradation. The results provide valuable insights into the dynamics characteristics of debris flow, which can facilitate engineers in preventing and mitigating debris flow disasters in mountainous regions.</p>

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Experimental study on the initiation mechanism of debris flow dry heads

  • 期刊论文

  • 发表日期：

    2025年12月20日

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  • Shizhengxiong Liang,
  • Dong Chen,
  • Zhiqiang Lai,
  • Dongri Song,
  • Yifei Cui

摘要

Through statistical analysis of pebble dynamics in debris flow heads, this study aims to uncover the underlying mechanisms governing the formation and maintenance of dry heads, which are more destructive than the tails. Laboratorial experiments were conducted using a custom flume with adjustable slopes, and the movement of pebbles was traced through high-speed photography. The two-phase debris flows were concocted by utilizing mixed-size spherical artificial pebbles and incorporating transparent fluids with varying viscosities and rheological properties. Our findings indicate that the debris flows manifest dry-head and hydrated-tail architectures only in scenarios characterized by steep slopes and low fluid viscosity (i.e., slope > 20°, fluidity index < 0.49, and consistency < 0.75). Upon partitioning the heads into saturated, near-bed dry, and air regions, our statistical analysis reveals that the pebbles in the saturated regions can replenish dry heads via both saturated-dry and saturated-air-dry paths. The widely accepted circulation pattern can be considered a case of the dual-path mode. Furthermore, we found that the particle-size segregation is not essential for the formation of dry heads, and the upward coarsening process may occur in the air regions resulting in inverse gradation. The results provide valuable insights into the dynamics characteristics of debris flow, which can facilitate engineers in preventing and mitigating debris flow disasters in mountainous regions.