Köprü ayağı oyulma derinliği ile düşey hız bileşeni arasındaki ilişkinin araştırılması

Öz

Köprü ayakları etrafında oluşan yerel oyulmalar önemli bir mühendislik problemi olarak kabul edilmektedir. Bu çalışmada, 6 cm ve 9 cm çapa sahip iki köprü ayağı, içinde 0.43 mm medyan dane çapında sediment bulunan 18 m uzuluğunda ve 70 cm genişliğinde dikdörtgen kesitli bir kanal içine yerleştirilmiş ve bu ayaklar etrafında oluşan oyulmalar ölçülmüştür. Her biri 4 saat sürdürülen 5 adet deney gerçekleştirilmiştir. Deneyler sırasında, oyulma derinliğinin zamanla değişimi ( ) ve ayağın 6 cm membasında tabandan 4 cm yukarıdaki noktasal hız değişimi zamana bağlı olarak kaydedilmiştir. Düşey hız bileşeni ( ) ile oyulma derinliği arasındaki ilişki araştırılmış ve bu parametrelerin boyutsuz biçimleri için bir denklem önerilmiştir. Sözkonusu bağıntının, literatürde bulunan sınırlı miktardaki çalışmaya ait veri ile uyum içinde olduğu görülmektedir.

Anahtar Kelimeler

• Köprü ayağı,Oyulma derinliği,Düşey hız,Zamanla değişim

References

1. Yanmaz M. “Yıkılan akarsu köprüleri üzerine görüşler”. Türkiye Mühendislik Haberleri, 420-421-422, 4-5-6, 137-141, 2002.
2. Shirhole AM, Holt RC. “Planning for a Comprehensive Bridge Safety Program”. Transportation Research Record 1290, Transportation Research Board, National Research Council, Washington, DC, USA, 1991.
3. Yanmaz M. Koprü Hidroliği. Ankara, Türkiye, METU Press, 2002.
4. Sümer BM, Christiansen N, Fredsoe J. “Influence of cross-section on wave scour around piles”. Journal of Waterway, Port, Coastal, and Ocean Engineering, 119(5), 477-495, 1993.
5. Melville BW, Chiew YM. “Time scale for local scour at bridge piers”. Journal of Hydraulic Engineering, 125(1), 59-65, 1999.
6. Oliveto G, Hager WH. “Further results to time-dependent local scour at bridge elements”. Journal of Hydraulic Engineering, 131(2), 97-105, 2005.
7. Lim SY. “Equilibrium clear-water scour around an abutment”. Journal of Hydraulic Engineering, 123(3), 273-243, 1997.
8. Ettema R. “Scour at Bridge Piers”. School of Engineering, University of Auckland, Auckland, New Zealand, 216, 1980.

9. Lauchlan CS. Pier Scour Countermeasures, Ph.D. Thesis, University of Auckland, Auckland, New Zelland, 1999.
10. Breusers HNC, Raudkivi AJ, Scouring, 1st Ed., AA. Balkema Rotterdam, Brookfield, 1991.
11. Baker CJ. “Laminar horseshoe vortex”. Journal of Fluid Mechanics, 95(2), 347-367, 1979.
12. Baker CJ. “The turbulent horseshoe vortex”. Journal of Wind Engineering Industrial Aerodynamics, 6(1-2), 9-23, 1980.
13. Baker CJ. “The position of points of maximum and minimum shear-stress upstream of cylinders mounted normal to flat plates”. Journal of Wind Engineering Industrial Aerodynamics, 18(3), 263-274, 1985.
14. Yulistiyanto B. “Velocity measurements on flow around a cylinder”. Dinamika Teknik Sipil, 9(2), 111-118, 2009.
15. Dargahi B. “Controlling mechanism of local scouring”. Journal of Hydraulic Engineering, 116(10), 1197-1214, 1990.
16. Melville BW. “Local Scour at Bridges Sites”. School of Engineering, University of Auckland, Auckland, New Zealand, 117, 1975.
17. Melville BW, Raudkivi AJ. “Flow characteristics in local scour at bridge piers”. Journal of Hydraulic Research, 15(4), 373-380, 1977.
18. Qadar A. “The vortex scour mechanism at bridge piers”. Proceedings ICE Res. Theory, 71(3), 739-757, 1981.
19. Muzzammil M, Gangadharaiah T. “The mean characteristics of horseshoes vortex at a cylindrical pier”. Journal of Hydraulic Research, 41(3), 285-297, 2003.
20. Sarker MA. “Flow measurement around scoured bridge piers using acourstic doppler velocimeter (ADV)”. Flow Measurement and Instrumentation, 9(4), 217-227, 1998.
21. Ahmed F, Rajaratnam N. “Flow around bridge piers”. Journal of Hydraulic Engineering, 124(3), 288-300, 1998.
22. Istiarto I. Flow Around a Cylinder in a Scoured Channel Bed. Ph.D. Thesis, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 2001.
23. Dey S, Raikar VR. “Characteristics of horseshoe vortex in developing scour holes at piers”. Journal of Hydraulic Engineering, 133(4), 399-413, 2007.
24. Das S, Das R, Mazumdar A. “Comparison of characteristics of horseshoe vortex at circular and square piers”. Research Journal of Applied Sciences, Engineering and Technology, 5(17), 4373-4387, 2013.
25. Unger J, Hager WE. “Down-flow and horseshoe vortex characteristics of sediment embedded bridge piers”. Experiments in Fluids, 42(1), 1-19, 2007.
26. Diab R, Link O, Zanke U. “Experimental investigation of 3D flow field around square pier”. 33rd IAHR Congress: Water Engineering for a Sustainable Environment, Canada, 2009.
27. Saçan C, Çetin OK, Bombar G. “Investigation of the scour inception around a circular bridge pier”. 2nd International Conference on Water, Energy and the Environment, Kusadasi, Turkey, 21-24 September 2013.
28. Bombar G. “Clear-Water bridge scour under triangular-shaped hydrographs with different peak discharges”. 2014 River Flow Conference, Lausanne, Switzerland, 2014.
29. Bombar G. “The hysteresis and shear velocity in unsteady flows”. Journal of Applied Fluid Mechanics, 9(2), 839-853, 2016.
30. Yulistiyanto B. Flow Around a Cylinder Installed in a Fixed-Bed Open Channel. Ph.D. Thesis, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 1997.
31. Furuichi N, Takeda Y, Kumada M. “Spatial structure of the flow through an axisymmetric sudden expansion”. Experiments in Fluids, 34(5), 643-650, 2003.
32. Blanckaert K., Flow and Turbulence in Sharp Open-Channel Bends. Ph.D. Thesis, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 2003.
33. Bombar G, Kantoush S, Albayrak İ. “Comparison of ADVP and UVP in terms of velocity and turbulence measurements in a uniform flow”. River Flow 2008, Çeşme, Turkey, 6-8 September 2008, Editors; M. S. Altınakar, N. Yıldırım, S. Y. Kumcu, G. Tayfur and M. Göğüş
34. Birjukova O, Guillen S, Alegria F, Cardoso AH. “Three dimensional flow field at confluent fixed-bed open channels”. River Flow 2014, Lausanne, Switzerland, 3-5 September 2014.
35. Duma D, Erpicum S, Archambeau P, Pirotton M, Dewals B. “Flow and turbulence characterization as an onset for assessing the stability of gravel beds”. River Flow 2014, Lausanne, Switzerland, 3-5 September 2014.
36. Simarro G, Fael CMS, Cardoso AH. “Estimating Equilibrium Scour Depth at Cylindrical Piers in Experimental Studies”. Journal of Hydraulic Engineering, 137(9), 1089-1093, 2011.
37. Melville BM. “Pier and abutment scour: integrated approach”. Journal of Hydraulic Engineering, 123(2), 125-136, 1997.