Relationships between starting motion of large-sized particles in debris flow and water flow condition

TANG Bihui1 SUN Hongyue1

(1.Ocean College, Zhejiang University, Hangzhou, Zhejiang, China 310058)

【Abstract】Debris flow occurs frequently in China, leading to great properties loss. Debris flow contains tremendous impact, most of which comes from large-sized particles. This paper investigates the relationships between the starting motion of large-sized particles and water flow condition. The study is focused on one spherical particle on the ramp and analyzes the particles’ forces, including lift force, tractive force and effective gravity. We solve the particles’random distribution on the ramp through probability method, and infer mathematical expectation of forces’arms. Additionally, the moment equilibrium equations of the starting condition for grains are solved. Therefore, we obtain the threshold velocity of the particle, which can be transformed into mean velocity at across-section. In the final, the relationships between starting motion of large-sized particles in debris flow and water flow condition are achieved, which provides a reference for building design of debris flow prevention, especially for the drainage device design.

【Keywords】 debris flow; large-sized particles starting; probability theory; starting flow velocity ; safe quantity of flow;


【Funds】 National Natural Science Foundation of China (41272336)

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This Article


CN: 23-1324/X

Vol 26, No. 03, Pages 132-138

June 2017


Article Outline



  • 1 Starting motion mechanism
  • 2 Instability discrimination of boulder in gully
  • 3 Formula verification
  • 4 Conclusions
  • References