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 ENG  Vol.10 No.8 , August 2018
Analysis on Scour Characteristics under River Bed Variation in Weir Downstream
Abstract: Various river projects are underway in small rivers in Korea that typically have natural flows. However, recent findings have shown that damages could be aggravated by structures such as weirs and drop structures during flood incidents. Experimental studies for securing the stability of flood control for these artificial structures have been insufficient, and designs applying the existing domestic design standards would not be suitable for the steep flow sections such as the actual small rivers, possibly aggravating the damages. The present study involved hydraulic model experiments conducted in a laboratory to investigate the surrounding flow patterns according to the river bed slope at the downstream part of the weir model. Further, the scour characteristics in the apron section during the overflow of the structure were analyzed to determine the appropriateness of the apron length. Thus, as the upstream river bed slope gradually increased, the experimental scour length deviated more from the design criteria formula. The results suggest that both the formula suggested by the National Construction Research Institute and Bligh’s formula presented in the River Design Criteria are not suitable for steep-slope rivers, such as small rivers in Korea, because both formulas were proposed based on the seepage line distance and river bed materials without considering the slope of the river bed. Thus, in designing the apron and bed pitching of weirs and drop structures, the river bed slope, scour characteristics of weir overflow, and existing design factors should be comprehensively considered to devise a design formula appropriate for environment of the small rivers in Korea.
Cite this paper: Ko, D. and Kang, J. (2018) Analysis on Scour Characteristics under River Bed Variation in Weir Downstream. Engineering, 10, 495-504. doi: 10.4236/eng.2018.108035.
References

[1]   Guan, D., Melville, B.W. and Friedrich, H. (2015) Live-Bed Scour at Submerged Weirs. Journal of Hydraulic Engineering, 141, 887-890.
https://doi.org/10.1061/(ASCE)HY.1943-7900.0000954

[2]   Lee, S.J. and Yoon, K.S. (2005) Safety Evaluation of Revetment around Barriers and Drop Structures. Korean Society of Civil Engineers, 887-890.

[3]   Lee, S.J., Yoon, K.S. and Hwangbo, J.G. (2006) Design of Revetment around Barriers and Drop Structures. Korean Society of Civil Engineers, 331-334.

[4]   Gaudio, R., Marion, A. and Bovolin, V. (2000) Morphological Effects of Bed Sills in Degrading Rivers. Journal of Hydraulic Research, 38, 89-96.
https://doi.org/10.1080/00221680009498344

[5]   Lenzi, M.A., Marion, A., Comiti, F. and Gaudio, R. (2002) Local Scouring in Low and High Gradient Streams at Bed Sills. Journal of Hydraulic Research, 40, 731-739.
https://doi.org/10.1080/00221680209499919

[6]   Lee, S.O., Yoon, S.E. and Song, J.W. (2011) Temporal Variation of Local Scour Depth in the Downstream of Weir with Shapes. Journal of Korean Society of Civil Engineers, 31, 353-360.

[7]   Lashkarara, B., Ghotbi, S.M.H. and Armaghani, A. (2012) Managing Local Scour Downstream of Cross-River Structures Case Study: Balaroud Inverted Siphon. World Applied Sciences Journal, 20, 570-576.

[8]   Helal, E.Y. (2014) Minimizing Scour Downstream of Hydraulic Structures Using Single Line of Floor Water Jets. Ain Shams Engineering Journal, 05, 17-28.
https://doi.org/10.1016/j.asej.2013.06.001

[9]   Ahmed, A.A.M. (2015) Physical Model Study for Mitigating Local Scour Downstream of Clear Over-Fall Weirs. Ain Shams Engineering Journal, 06, 1143-1150.
https://doi.org/10.1016/j.asej.2015.03.013

[10]   Shafai, B.M., Nabavi, S.M.R. and Dey, S. (2016) Scour Downstream of Grade Control Structures under the Influence of Upward Seepage. Acta Geophysica, 64, 694-710.
https://doi.org/10.1515/acgeo-2016-0024

[11]   KWRA (2009) Rivers Design Criteria & Commentary. KWRA, Korea.

[12]   Hussein, K.B., Dardier, M.A., Seif, A.K. and Elsheemy, A.A. (2017) Studying Effect Inclination of Cutoff on the Percolation Length under Aprons of Hydraulic Structures Founded on Isotropic Soil. International Research Journal of Engineering and Technology, 04, 1208-1224.

 
 
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