Experimental investigation of effect of the apron installation on local scour at the downstream of block ramp

Document Type : Research Paper

Authors

1 Department of water engineering, Faculty of Agriculture Science, University of Guilan, Rasht

2 Department of Water Engineering, Faculty of Agriculture Science, University of Guilan, Rasht, Iran; Department of Water and Environmental Engineering, Caspian Sea Basin Research Center, University of Guilan, Rasht, Iran

3 Department of water Engineering, Faculty of Agriculture Science, University of Guilan, Rasht

4 IA.ING, Lecce, Italy

Abstract

River bed control is a critical issue that river engineers facing with it today. Block ramps are grade control structures, implementing as a countermeasure to overcome successive erosion in rivers bed, having suitable environmental conditions in terms of aquatic migration to upstream reaches, and also increasing the dissolved oxygen in the water. One of the important issues in designing and safetying these structures is to predict and reduce the magnitude of scour depth in the downstream pools. In the present study, the effect of apron installation on the reduction of scour in the downstream of the block rams under the smooth and rough surface of the structure was investigated, experimentally. The experiments were performed for slopes of 1:3 and 1:5, the ratio of the critical depth to the height of the structure 0.14-0.2, roughness elements height of 1.15-5.2 cm with different arrangements; as well as apron installation with a length of equal and half of the height of the structure at the hydraulic and physical hydraulic lab of University of Guilan in 2020 and 2021. The comparison of the results of all slopes of the structures showed that the apron installation is directly related to the reduction of the maximum scour depth, so that by installing an apron with length of equal to the structure height, the maximum scour depth for slopes 1:3 and 1:5 reduced by an average of 58 and 43%, respectively, compared to the smooth block ramp. By increasing the roughness height, the maximum scour depth over the range of minimum and maximum flow discharges and the structures slopes reduced by an average of 39 to 62 % compared to the corresponding smooth block ramp. A comparison of the results shows that for block ramp with the slope of 1:3, changing the roughness arrangement from staggered to compact in case of large roughness, had no effect on reduction of the maximum scour depth, but in the slope of 1:5, reduced the maximum scour depth in the range of 18 to 42 %.

Keywords

References

Ali, H. M., El Gendy, M. M., Mirdan, A. M. H., Ali, A. A. M., and Abdelhaleem, F. S. F. (2014). Minimizing downstream scour due to submerged hydraulic jump using corrugated aprons. Ain Shams Engineering Journal, 5(4), 1059-1069.
Aamir, M., and Ahmad, Z. (2017). Prediction of Local Scour Depth Downstream of an Apron Under Wall Jets. Department of Civil Engineering, Indian Institute of Technology Roorkee, 375-385.
Aamir, M., and Ahmad, Z. (2019). Estimation of maximum scour depth downstream of an apron under submerged wall jets. Journal of Hydroinformatics, 21(4), 523–540.
Aamir, M., and Ahmad, Z. (2021). Effect of apron roughness on flow characteristics and scour depth under submerged wall jets. Acta Geophys. https://doi.org/10.1007/s11600-021-00672-9.
Basic Design for Erosion Control in Streams and Channels Structures No. 417. (2009). Islamic Republic of Iran Vice presidency for strategic planning and supervision.
Bhuiyan, F., Hey, R. D. and Wormleaton, P. R. (2007). Hydraulic evaluation of W-weir for river restoration. Journal of Hydraulic Engineering, 133(6), 596-609.
CBIP. 1989. River behavior management and traiing, CBIP Rep. Centtral Board Irrigation power, New Dehli, India.
Chaudhary, R.K., Ahmad, Z. and Mishra, S.K. (2021). Scour downstream of a corrugated apron under wall jets. Water Practice and Technology, 17(1), 204-222.
Dey, S. and Raikar, V. (2005). Scour in long contractions. Journal of Hydraulic Engineering, 131(12), 1036–1049.
Dey, S. and Raikar, R.V. (2007). Scour below a high vertical drop. Journal of Hydraulic Engineering, 133(5), 564-568.
Esmaeili Varaki, M., Mahmoudi Kurdistani, S., and Noormohammadi, G. (2021). Scour Morphology Downstream of Submerged Block Ramps. Journal of Applied Water Engineering and Research. 1-10.
Hoffmans, G.J.C.M. and H.J, Verhij. (1997). Scour Manual. A.A Balkema. Rotterdam. Brookfield
Hoffmans Gijs, J.C.M. (1998). Jet scour in equilibrium phase. Journal of Hydraulic Engineering, 124(4), 430–437.
Hamidifar, H. and Omid, M.H. (2010). Noncohesive Sediment Scour Downstream of an Apron. Journal of Agricultural Engineering Research, 11(2), 17-28.
Jarrett, R.D. (1984). Hydraulics of high gradient streams. Journal of Hydraulic Engineering, 110(11), 1519–1539.
Kazempour Larsari, Z., Esmaeili Varaki, M., and Malekpour, A. (2019). Laboratory Study of Scour Downstream of Stepped-labyrinth Weirs. Iranian Journal of Soil and Water Research, 49(6), 1227-1241.
López, C.D.L. F. (1993). Torrent control and streambed stabilization. Food and Agriculture Organization of the United Nations, 166PP.
Mehboudi, A. (2009). Experimental Study on Control of Scouring in Rivers due to Submerged Horizontal jet. M. SC. dissertation, Power and Water University of Technology in IRAN, Tehran
Oertei, M. (2013). In-Situ Measurements On Cross-Bar Block Ramps. Journal of Hydraulic Engineering Repository, 111-119.
Ortel, M. and Bung, D.B. (2015). Stability and scour development of bed material on crossbar block ramps. International Journal of Sediment Research, 30(4), 334–350.
Petersen, M. (1986). River engineering. Prentice Hall, USA, 580PP.
Pagliara, S. and Chiavaccini, P. (2006a). Energy dissipation on reinforced block ramps. Journal of Irrigation and Drainage Engineering, 132(3), 293–297.
Pagliara, S. and Chiavaccini, P. (2006b). Energy dissipation on block ramps. Journal of Hydraulic Engineering, 132(1), 41–48.
Pagliara, S. and Chiavaccini, P. (2006c). Flow resistance of rock chutes with protruding boulders. Journal of Hydraulic Engineering, 132(6): 545–552.
Pagliara, S. (2007). Influence of sediment gradation on scour downstream of block ramps. Journal of Hydraulic Engineering, 133(11), 1241–1248.
Pagliara, S., Das, R., and Carnacina, L. (2008). Flow resistance in large-scale roughness condition. Canadian Journal of Civil Engineering, 35(11), 1285–1293.
Pagliara, S. and Palermo, M. (2008). Scour control downstream of block ramps. Journal of Hydraulic Engineering, 134(9), 1376-1382.
Pagliara, S. and Palermo, M. (2009). Scour and hydraulic jump downstream of block ramps in expanding stilling basins. Journal of Hydraulic Engineering, 47(4), 503–511.
Pagliara, S. and Palermo, M. (2010). Influence of tailwater depth and pile position on downstream of block ramps. Journal of Irrigation and Drainage Engineering, 136(2), 120–130.
Pagliara, S. and Palermo, M. (2011). Effect of stilling basin geometry on clear water scour morphology downstream of a block ramp. Journal of Irrigation and Drainage Engineering, 137(9), 593–601.
Pagliara, S. and Palermo, M. (2013). Rock grade control structures and stepped gabion weirs: Scour analysis and flow features. Acta Geophysica, 61(1), 126-150.
Pagliara, S. and Kurdistani, S.M. (2013). Scour downstream of crossvane structures. Journal of Hydraulic-Environ Repository, 7(4), 236–242.
Pagliara, S., Palermo, M, Kurdistani, S. M., and Hassanabadi, L. S. (2015). Erosive and hydrodynamic processes analysis downstream of low-head rock made control structures. Journal of Applied Water Engineering and Research, 3(2), 122–131.
Pagliara, S., Radecki-Pawlik, A., Palermo, M., and PlesiÇıski, K. (2017). Block ramps in curved rivers: morphology analysis and prototype data supported design criteria for mild bed slopes. River Research and Applications, 33(3), 427–437.
Pagliara, S., Palermo, M., and Roy, D. (2020). Experimental investigation of erosion processes downstream of block ramps in mild curved channels. Environmental Fluid Mechanics, 20(8), 339–356.
Rajaratnam, N. and Macdougall, R. K. (1983). Erosion by plane wall jets with minimum tailwater. Journal of Hydraulic Engineering, 109(7), 1061-1064.
Robinson, K.M., Rice, C.E., and Kadavy, K.C. (1998). Design of rock chutes. Transactions of the ASAE, 41(3), 621–626.
Sarkar, A., and Dey, S. (2005). Scour downstream of aprons caused by sluices. In Proceedings of the Institution of Civil Engineers-Water Management, 158(2), 55-64.
Scurlock, S.M., Thornton, C.I., and Abt, S.R. (2012). Equilibrium scour downstream of three-dimensional grade control structures. Journal of Hydraulic Engineering, 138(2), 167–176.
Iranian Journal of Soil and Water Research
Volume 53, Issue 6
August 2022
Pages 1259-1279

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