파랑하 해저관로 주변의 세굴폭에 영향을 주는 매개변수 분석

Parameter Analysis for Influence on the Scour Width around Submarine Pipelines in Waves

  • Oh, Hyoun-Sik (Department of Civil Engineering, Chungbuk National University) ;
  • Kim, Kyoung-Ho (Department of Civil Engineering, Chungbuk National University) ;
  • Son, Kwang-Sik (Department of Civil Engineering, Chungbuk National University) ;
  • Kim, Heung-Guk (Department of Civil Engineering, Chungbuk National University)
  • 발행 : 2009.12.31

초록

파에 의한 국부세굴은 하상재료의 지질학적 특성과 해저 하상의 유동은 물론, 수리학적 조건에 의해서도 영향을 받게되는 매우 복잡한 종합적 과정으로 생각할 수 있다. 지금까지의 대부분의 연구는 세굴심을 중점 대상으로 하였으나 전체 국부 세굴량 산정에 있어서 세굴 폭과의 관련성은 상대적으로 미미하게 다루어져왔다. 많은 국부세굴 영향인자 중에서도 파의 크기 혹은 해저 바닥에서의 유속은 국부세굴의 직접적인 원인으로서 작용하며, 이를 포함하는 Ursell 수나 KC 수 등의 무차원 매개변수는 세굴 영역과의 상관성 분석을 통해 세굴심이나 세굴폭을 예측할 수 있는 수단이 될 수 있다. 본 논문에서는 이러한 무차원 매개변수와 세굴 폭과의 관계를 규명하기 위해, 관경, 파고, 주기를 변화시키며 실험을 수행 및 분석하였다. 그 결과, Re 수나 주기 매개변수 등은 국부세굴 폭과 큰 분산을 보인 반면에 shields 수와 KC 수, Ursell 수는 좋은 상관성을 나타내었다. 특히 shields 수는 세굴심에 큰 영향을 주지 못하는 반면 세굴 폭과는 밀접한 관계를 보이고 있다.

The local scour in waves can be thought of as very complex synthetic processes which is influenced by geology of bed material, bed flow in the sea and hydraulics condition. The most research until now be targeted at the scour depth and therefore the local scour width in waves has not been investigated as well. The size of wave or bottom velocity at the bed is direct cause of the local scour among lots of the scour effect factors, and the scour depth and width can be estimated through interrelationship analysis with scour area to use the dimensionless parameters including these such as Keulegan-Carpenter number, Ursell number etc. In this paper, to find out closely relation with the dimensionless parameters and scour width, performed an experiment with the variations of pipe diameters, wave heights and wave periods and then analyzed it. As the result, while Reynolds number and period parameter were seen to disperse local scour width largely, Shields number, KC number and Ursell number appeared good interrelationship. Specially, Shields number doesn't much affect the scour depth but has good relation for the scour width.

키워드

참고문헌

  1. 김경호, 김홍훈, 오현식, 연주흠 (2005). 파랑에 의한 해저 매설관로 주변의 국부세굴 특성, 한국해안해양공학회지, 제17권 제 2호, pp. 106-118
  2. 오현식, 이호진, 김경호 (2002). 파에 의한 해저관로의 국부세굴 특성, 대한토목학회논문집, 제 22권 제 4-B호, pp.539-549
  3. Sumer, B.M., Truelsen, C., Shchmann, T. and Fredoe, J. (2001). Onset of scour below pipelines and self-burial, An International Journal for coastal, Harbour and Offshore Engineers., pp. 313-335
  4. Chiew, Y. M. et al. (1993). Effect of Spoilers on Wave-Induced Scour at Sub-marine pipeline, Journal of Waterway, port, Coastal, and Ocean Engineering, ASCE, Vol. 119, No 4
  5. Esin Cevik and Yal in Yüksel. (1999). Scour under Submarine Pipelines in Waves in Shoaling Conditions, Journal of Waterway, Port, Coastal, and Ocean Engineering, Vol. 125, No. 1
  6. Herbich, J.B. (1981). Scour around Pipelines and Other Objects, Offshore Pipeline Design Elements, Marcel Dekker Inc., New York., pp. 43-96
  7. Kjeldsen, S.P., et al. (1973). Local scour near offshore pipelines, Proc. Sec-ond Int. Port and Ocean Engrg. under Arctic conditions Conf., pp. 308-331
  8. Klomp, W.H.G., Hansen, E.A., Chen, Z., Bijker, R. and Bryndum, M.B. (1995). Pipeline seabed interaction, free span development, The international Society of Offshore and Polar Engineers, The Gague, Netherlands
  9. Lucassen, R.J. (1984). Scour underneath submarine pipelines, Report No. PL- 42A, Netherlands Marine Tech. Res., Netherlands Industrial Council for Oceanology, Delft University of Technolty, Delft, the Netherlands, Sep. 1984. Student Thesis supervised by E. W. Bijker and W. Leeuwenstein
  10. Smer and Fredse. (1990). Scour Below Pipelines in Waves, Journal of waterway, port Coastal, and Ocean Engineering, ASCE, Vol. 116, No.3, May/June
  11. Sumer, B.M., Mao, Y. and Fredsoe, J. (1988). Interaction between vibrating pipe and erodible bed, J. Wtrway., Port, Coast. and Oc. Engrg., ASCE, 144(1), pp. 81-92
  12. Sumer, B.M. and Fredsoe, J. (2001). Scour Around Pile In Combined Waves and Currents, Journal of Hydraulic Engineering, May, pp. 403-411
  13. Yuksel, Y. and Narayanan, R. (1994). Wave Forces on Horizontal Cylinder Resting on Sloping Bottom, Proceedings of 4th International Offshore and Polar Engineering Conference, Vol. 2, pp. 85-92
  14. Yuksel, Y., Ath, V. and Cevik, E. (1995). Flow Field along a flat surface with a parallel placed cylinder, Proc., 5th Int. Offshore and Polar Engrg. Conf., International Society of Offshore and Pollar Engineering, Golden, Colo., pp. 157-170