Velocity Attenuation of Granular Debris Flows During Impact on Rigid Barriers

  • C. H. Raymond KooEmail author
  • S. H. Julian Kwan
  • Carlos Lam
  • Wai-Keung Pun
  • W. W. Charles Ng
  • E. Clarence Choi
Conference paper


Effective design of rigid debris-resisting barriers remains a challenging problem for practitioners. At present, a pseudo-static approach is commonly used for the estimation of debris impact loads acting on barriers. In this approach, the dynamic impact pressure is estimated using the hydrodynamic equation and an assumed value of the dynamic pressure coefficient. The bulk density and travel velocity of the landslide debris are also required for the calculations. To this end, the debris velocity under free-field conditions can be obtained from a conventional debris mobility assessment. A limitation of this approach is that it ignores the attenuation of the debris’ velocity during the deposition process behind the barrier. To provide a scientific basis for assessing the velocity of granular debris flows during impact on rigid barriers, this paper presents results of debris velocity from a laboratory study of debris-barrier interaction using physical flume modelling. High-speed cameras were used to capture the dynamic motion of the flowing debris. The images obtained were analysed using the particle image velocimetry (PIV) technique to estimate the velocity of the debris. The results show that, following the first stage of impact, the accumulated debris behind the model barrier formed a stationary zone and caused the remaining debris to slow down in a run-up process. As a result, the peak debris momentum was 30% lower compared to that observed under free-field conditions. The findings of this study will allow practitioners to optimise the design of debris-resisting barriers in the future.


Granular debris flow Velocity attenuation Rigid barrier Flume modelling 



This paper is published with the permission of the Head of the Geotechnical Engineering Office and the Director of Civil Engineering and Development, Hong Kong SAR Government. The work described in this paper was supported by a grant from the Research Grants Council of the Hong Kong SAR (HKUST T22-603/15N). The authors would also like to acknowledge the support of the HKUST Jockey Club Institute of Advanced Study.


  1. Armanini A, Larcher M, Odorizzi M (2011) Dynamic impact of a debris flow against a vertical wall. In: Proceedings of the 5th international conference on debris-flow hazards mitigations: mechanics, prediction, and assessment, Padua, Italy, 14–17 June 2011, pp 1041–1049Google Scholar
  2. Ashwood W (2014). Numerical model for the prediction of total dynamic landslide forces on flexible barriers. Master’s thesis of applied science, geological engineering, The University of British Columbia, p 162Google Scholar
  3. Choi CE, Ng CWW, Song D, Kwan JSH, Shiu HYK, Ho KKS, Koo RCH (2014) Flume investigation of landslide debris—resisting baffles. Can Geotech J 51(5):540–553CrossRefGoogle Scholar
  4. Fitze P (2010). Runout analysis of rapid, flow-like landslides. Master’s thesis, Hochschule für Technik Rapperswil, Rapperswil-Jona, St. Gallen, p 101Google Scholar
  5. Hubl J, Suda J, Proske D, Kaitna R, Scheidl C (2009). Debris flow impact estimation. In: Proceedings of the 11th international symposium on water management and hydraulic engineering, Ohrid, Macedonia, 1–5 Sept 2009, pp 137–148Google Scholar
  6. Hungr O (1995) A model for the runout analysis of rapid flow slides, debris flows and avalanches. Can Geotech J 32(4):610–623CrossRefGoogle Scholar
  7. Hungr O (2008) Simplified models of spreading flow of dry granular material. Can Geotech J 45(8):1156–1168CrossRefGoogle Scholar
  8. Iverson R, Logan M, LaHusen R, Berti M (2010) The perfect debris flow? Aggregated results from 28 large scale experiments. J Geophys Res 115:F03005CrossRefGoogle Scholar
  9. Kwan JSH (2012). Supplementary technical guidance on design of rigid debris-resisting barriers, GEO report no. 270. Geotechnical Engineering Office, Hong Kong, p 88Google Scholar
  10. Kwan JSH, Koo RCH (2015). Enhanced technical guidelines for design of debris-resisting barriers. Technical note no. TN 2/2015, Geotechnical Engineering Office, Hong Kong, p 33Google Scholar
  11. Kwan JSH, Sun HW (2006) An improved landslide mobility model. Can Geotech J 43(5):531–539CrossRefGoogle Scholar
  12. Kwan JSH, Koo RCH, Ng CWW (2015) Landslide mobility analysis for design of multiple debris-resisting barriers. Can Geotech J 52(9):1345–1359CrossRefGoogle Scholar
  13. MLR (2006). Specification of geological investigation for debris flow stabilization. DZ/T 0220–2006. National Land Resources Department, China, p 32. (in Chinese)Google Scholar
  14. NILIM (2007). Manual of technical standard for establishing sabo master plan for debris flow and driftwood. Technical note of NILIM No. 364, Natural Institute for Land and Infrastructure Management, Ministry of Land, Infrastructure and Transport, Japan, p 18 (in Japanese)Google Scholar
  15. Peng C, Chao Z, Yu L (2015) Experimental analysis on the impact force of viscous debris flow. Earth Surf Proc Land 40(12):1644–1655CrossRefGoogle Scholar
  16. Tiberghien D, Laigle D, Naaim M, Thibert E, Ousset F (2007) Experimental investigations of interaction between mudflow and an obstacle. In: Proceedings of the 4th international conference on debris-flow hazards mitigation: mechanics, prediction, and assessment, Chengdu, China, 10–13 Sept 2007, pp 281–292Google Scholar
  17. VanDine DF (1996) Debris flow control structures for forest engineering. Ministry of Forests, British Columbia, Canada, 68 pGoogle Scholar
  18. White DJ, Take WA, Bolton MD (2003) Soil deformation measurement using particle image velocimetry (PIV) and photogrammetry. Géotechnique 53(7):619–631CrossRefGoogle Scholar

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • C. H. Raymond Koo
    • 1
    Email author
  • S. H. Julian Kwan
    • 1
  • Carlos Lam
    • 1
  • Wai-Keung Pun
    • 1
  • W. W. Charles Ng
    • 2
  • E. Clarence Choi
    • 2
  1. 1.Geotechnical Engineering Office, Civil Engineering and Development DepartmentThe Government of the Hong Kong Special Administrative RegionHong KongChina
  2. 2.Department of Civil and Environmental Engineering, Clear Water BayHong Kong University of Science and TechnologyHong KongChina

Personalised recommendations