Experimental study of Bed Pattern around the Cylindrical Pile under Broken Waves

Document Type : Research Paper

Authors

Faculty of Civil Engineering, Sahand University of Technology, East Azerbaijan Province, Tabriz, Iran.

Abstract

Cylindrical piles are often used in most of coastal and offshore structures such as bridges, wharfs, offshore wind turbine foundations and Oil platforms. Most of these structures are installed in shallow water and exposed to strong currents, waves and broken waves. These phenomena can cause scour around them which can damage their structural integrity and stability. In literature, scour process around the cylindrical piles under currents and waves have been studies frequently. However, there are very little knowledge about the bed forms due to the broken waves. In this paper, the effect of broken waves on the characteristics of bed forms around a cylindrical pile has been studied experimentally in a large wave flume. The three-dimensional bed topography was measured by Close Range Photogrammetry. Vortex ripples and truncated cone scour with vortex ripples were the main observed scour pattern. Shields parameter as well as Keulegan-Carpenter (KC) number were used as the non-dimensional parameters for bed form classification. It is noticed that the ripple height and ripple steepness for broken regular waves is less than non-breaking regular waves. However, the relative equilibrium scour depth for broken waves is larger than non-breaking waves.

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References

  1. Sumer B.M., Christiansen N. and Fredsøe J., (1997). The horseshoe vortex and vortex shedding around a vertical wall-mounted cylinder exposed to waves. J. Fluid Mechanics, pp: 332:41-70.
  2. Sumer B.M., Fredsøe L., The Mechanics of Scour in the Marine Environment, World Scientific Pub., Singapore, 2002.
  3. Shields A., (1936). Anwendung der Ähnlichkeitsmechnik und der Turbulenz Forschung auf die Geschiebebewegung Mitt, der Preuss. Versuchsamst. Für Wasserbau und Schiffbau, Heft 26, Berlin, Deuschland.
  4. Jonsson I.G., (1966). Wave boundary layer and friction factors. Proc. 10thCoastal Engineering Conf., Tokyo, Japan, pp: 1:127-148
  5. Jonsson I.G., (1980). A new approach to oscillatory rough turbulent boundary layers. Ocean Engineering, pp: 7:109-152.
  6. Fredsøe J., and Deigaard R., Mechanics of Coastal Sediment Transport. World Scientific Pub., Singapore, (1992).
  7. Allen J.R.L., Sedimentary Structures, Their Character and Physical Basis. Elsevier’s Science Pub., The Netherlands, (1982).
  8. Dingler J.R., and Inman B.L., (1976). Wave-formed ripples in nearshore sands. Proc. 15th Coastal Engineering Conf., Honolulu, Hawaii, pp:
  9. Horikawa K., Watanabe A., and Katori S., (1982). Sediment transport under sheet flow conditions. Proc. 18thCoastal Engineering Conf., Cape Town, S. Africa, pp: II: 1335-1352
  10. Wilson K.C., (1989). Friction of wave-induced sheet flow. Coastal Engineering, pp: 12.
  11. Chiew Y.M. and Melville B.W., (1987). Local scour around bridge piers. J. Hydraulic research, pp: 25(1):15-26.
  12. Sumer B. M., Fredsøe J., and Christiansen N., (1992). Scour around vertical pile in waves. Journal of waterway, port, coastal, and ocean engineering, pp: 118(1):15-31.
  13. Melville B.W., (1997). Pier and abutment scour: integrated approach. Journal of hydraulic Engineering, pp: 123(2):125-136.
  14. Melville B. and Coleman S., Bridge scour, Water Resources Pub., LLC, Colorado, 2000.
  15. Sumer B. M., Whitehouse R. J., and Tørum A., (2001). Scour around coastal structures: a summary of recent research. Coastal Engineering, pp: 44(2):153-190.
  16. Sumer B.M., Fredsøe L., (2001). Wave scour around a large vertical circular cylinder. Journal of waterway, port, coastal, and ocean engineering, pp: 127(3):20520.
  17. Sheppard, D. M. Large-scale and live-bed local pier scour experiments. Coastal Engineering Technical Rep. No. 133, Civil and Coastal Engineering Dept., Univ. of Florida, Gainesville, 2003.
  18. Coleman S., (2005). Clear water local scour at complex piers. J. Hydraul. Eng., pp: 131(4): 330–334.
  19. Elsebaie I.H., (2013). An experimental study of local scour around circular bridge pier in sand soil. International Journal of Civil & Environmental Engineering IJCEE-IJENS, pp: 13(01):23-28, 2013.
  20. Amini Baghbadorani D., Beheshti A.A., and Ataie-Ashtiani B., (2017). Scour hole depth prediction around pile groups: review, comparison of existing methods, and proposition of a new approach. Natural Hazards, pp: 88:977-1001.
  21. Chen B., and Li S. (2018). Experimental study of local scour around a vertical cylinder under wave only and combined wave-current conditions in a large-scale flume. J. of Hydraulic Engineering, pp:144(9):04018058.
  22. Gazi A.H., Afzal M. S., and Dey S., (2019). Scour around piers under waves: Current status of research and its future prospect. Water, pp: 11:2212.
  23. Liang B., Du S., Pan X., and Zhang L., (2019). Local scour for vertical piles in steady currents: review of mechanisms, influencing factors and empirical equations. Journal of Marine Science and Engineering, pp: 8(1):4.
  24. Guan D., Xie Y., Yao Z., Chiew Y., Zhang L. and Zheng J., (2022). Local scour at offshore wind farm mono pile foundations: A review. Water Science and Engineering, pp:15(1):29-39.
  25. Li J., Guo Y., Lian J., and Wang H., (2023). Mechanisms, assessments, countermeasures, and prospects for offshore wind turbine foundation scour research. Ocean Engineering, pp: 281 (114893).
  26. Umeda S., (2011). Scour regime and scour depth around a pile in waves. J. of Coastal Research, pp: 64:845-849.
  27. Otsuka J., Saruwatari A., and Watanabe Y., (2017). Vortex-induced suspension of sediment in the surf zone. Advances in Water Resources, pp: 110: 59-76.
  28. Bijker E.W., and de Bruyn C.A., (1988). Erosion around the pile due to the current and breaking waves. Proc. 21st. Coastal Engineering Conf., ASCE, Reston, USA, pp: 2:1368-1381.
  29. Carreiras J., Larroudé Ph., Seabra-Santos F.J., and Mory M., (2000). Wave scour around piles. Proc. 27th Coastal Engineering Conf., ASCE, Sydney, Australia, pp: 2:1860-1870.
  30. Frigaard P., Hansen E.A., Christensen E.D. and Jensen M.S., (2005). Effect of breaking waves on scour processes around circular offshore wind turbine foundations. NWTC External Web Site National Wind Technology Center.
  31. Nielsen A.W., Sumer B.M., Ebbe S.S., and Fredsøe J. (2012). Experimental study on the scour around a monopile in breaking waves. Journal of waterway, port, coastal, and ocean engineering, pp:138(6):501-506.
  32. Liu C., Zhu X., He Y., Wang Q. and Wu Z., (2020). 3D modeling and mechanism analysis of breaking wave-induced seabed scour around monopile. Mathematical Problems in Engineering. https://doi.org/10.1155/2020/1647640.
  33. Goda Y., and Suzuki T., (1976). Estimation of incident and reflected waves in random wave experiments. Proc. 15th International Conference on Coastal Engineering., ASCE, Honolulu, USA, pp:828-845.
  34. Kiasalary A., and Mostafa Gharabaghi A.R., (2023). Estimation of Bed Topography near the Cylindrical Pile under Breaking Waves by Close Range Photogrammetry. Int. J. of Coastal, Offshore and Environmetal Engineering, pp: 8(3): 32-39.
  35. Van Rijn L.C., Handbook of sediment transport by currents and waves. Report H461, Delft Hydraulics, Delft, Netherlands, 1989.
  36. Dogan M., (2021). The equilibrium depth of wave scours around both slender and large piles. Ocean Engineering, pp: 236: 109474.

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