Derivation and application of formula for sediment incipient velocity in inclined siphon drainage pipe

WU Xian1 WANG Lei2 SUN Hongyue1

(1.Ocean College, Zhejiang University, Zhoushan China 316000)
(2.College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, Zhejiang Province, China 310058)

【Abstract】Siphon drains in slope, a novel slope drainage measure with lower construction cost and higher construction speed, can effectively reduce the slope’s groundwater level. For the slopes with large slippery bodies, the inclined siphon method can be used to drain the deep groundwater. For the long-term stability of the siphon process, the diameter of siphon is usually 4 mm. In view of the intermittent characteristics of slope siphon drainage, it is the foundation for the siphon drainage system to ensure that the sediment, especially the large particles in the pipe, can be discharged smoothly with the water flow. This paper studied the incipient motion of large granular sediment with a particle size of 0.5–1 mm in an inclined siphon, and the relative stress state of sediment was analyzed while the incipient model was established. Based on the theory of incipient probability, the particle size distribution of sediment was analyzed, and the theoretical formula of the incipient velocity for large particles in inclined siphon was obtained by deduction. The accuracy was verified with the classical analytical formula and the results of physical model tests, and the application of the incipient velocity formula in the actual siphon drainage project was analyzed and forecasted.

【Keywords】 siphon drainage in slope; inclined siphon; large particle; probability theory; incipient velocity;


【Funds】 National Natural Science Foundation of China (41772276) Key R&D Project of Zhejiang Province, China (2017C03006)

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(Translated by LIU T)


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This Article


CN: 23-1324/X

Vol 27, No. 05, Pages 54-62

October 2018


Article Outline


  • 1 Incipient mechanism of large particles in inclined boreholes
  • 2 Derivation of incipient velocity
  • 3 Equation verification
  • 4 Application of equations
  • 5 Conclusions
  • References