Investigation of Live-Bed Scour at Labyrinth Side Weirs

Yıl 2018, Cilt: 13 Sayı: 1, 129 - 136, 01.03.2018

Mustafa Tunç M. Emin Emiroğlu

Öz

Side weirs, also known as lateral weirs, and
overflow dams are free overflow regulation and diversion devices commonly
encountered in hydraulic engineering. The lateral loss of water is reducing the
sediment transport capacity in the main-channel and the formation of a local
sediment deposit in the downstream of weir. The head over the side weir rises
and the side overflow discharge as well. The design discharge to be diverted
over the weir is increased by this flow-sediment transport interaction. Although
there were no studies that scrutinized the scouring depth and geometry that
occurs around the labyrinth side weirs in channels with movable bed, there are
limited number of studies that examined the scouring geometry around the
classical side weir. In the present study, local scour depths formed in the
periphery of triangular labyrinth side weir mounted in a live-bed rectangular
cross-section straight channel were experimentally investigated under steady
state flow and free overflow from the side weir conditions. To provide for
live-bed conditions, the sediment was added to bed material in the experiments.
A series of experiments were conducted for live-bed scouring conditions (for
flow intensity greater than one) to determine the maximum scour depths that occur
around the triangular labyrinth side weir with different flow depths, different
main channel discharges, different volumetric amounts of sediment feed,
different crest heights, different Froude numbers, different flow intensities
and using uniform bed material. In the experiments, the dimensions of the
scours and sediment deposits that occur upstream and downstream of the weir
exhibited a periodic change (increase and decrease). The maximum depth of scour
occurred at the downstream end of the triangular labyrinth side weir
frequently.

Anahtar Kelimeler

Triangular labyrinth side weir, Flow intensity, Local scour, Live-bed scour, Sediment transport

Kaynakça

• 1. Rosier, B., Boillat, J. L., and Schleiss, A. J. (2011). “Influence of lateral water withdrawal on bed form geometry in a channel.” Journal of Hydraulic Engineering, 10.1061/(ASCE)HY.1943-7900.0000472, 1668-1675. 2 .Paris, E., Solari, L., and Bechi, G. (2012). “Applicability of the De Marchi hypothesis for side weir flow in the case of movable beds.” Journal of Hydraulic Engineering, 10.1061/(ASCE)HY.1943-7900.0000566, 653-656. 3. Onen, F., and Agaccioglu, H. (2013). “Live bed scour at a side‐weir intersection located on an alluvial channel.” Irrigation and Drainage, 62(4), 488-500. 4. Tunc, M., and Emiroglu, M. E. (2014). “Effect on bed topography of labyrinth side weirs located in movable bed rivers.” With International Participation 4th National Symposium and Exposition on Dam Safety, 759-770 (in Turkish). 5. Emiroglu, M. E., Kaya, N., and Agaccioglu, H. (2010). “Discharge capacity of labyrinth side weir located on a straight channel.” J. Irrig. and Drain. Eng., 10.1061/(ASCE)IR.1943-4774.0000112, 37-46. 6. USBR., 2001. Water measurement manual, 3rd Edition, Water Resources Research Laboratory, Bureau of Reclamation, U. S. Department of the Interior. 7. Emiroglu, M. E., Kaya, N. ve Dogan, Y. (2010). The effect of shape of crest on discharge coefficient in weirs, DSİ Technical Bulletin, 108, 57-70 (in Turkish). 8. Tunc, M. (2014). An investigation of the hydrodynamics of flow at the labyrinth side weirs in the movable bed rivers, Firat University, Graduate School of Science (in Turkish). 9. Bayazit, M., and Avci I. (2010). Flow in streams and sediment transport, Istanbul Technical University, Civil Engineering Faculty Press, Istanbul (in Turkish). 10. Novak P. and Cabelka J. (1981). Models in Hydraulic Engineering, Pitman Publishing Limited, London. 11.Tsujimoto, T. and Mizukami T. (1985). Effect of migration to local scour around a bridge pier, Memoirs, Faculty of Technology, Kazanawa University, 19(1): 23-34. 12.Yanmaz, A. M., and Altınbilek, H. D. (1991). “Study of time –dependent local scour around bridge piers.” Journal of Hydraulic Engineering, 10.1061/(ASCE)0733-9429(1991)117:10(1247) 1247-1267