PSI - Issue 62

Michele Palermo et al. / Procedia Structural Integrity 62 (2024) 593–600 Author name / Structural Integrity Procedia 00 (2019) 000–000

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effective in the absence of debris accumulation. Conversely, their effect in limiting and controlling the scour process reduces with the blockage area caused by the debris accumulation. Nonetheless, the kinetics of the scour is delayed for all the cases. By comparing the effects of the sill/gabion and macro-roughness elements on scour features under identical hydraulic conditions, it was possible to conclude that the latter generally performs better, especially when sills are located very close to the pier. Furthermore, macro-roughness elements do not represent a threat to bank stability, since they can also contribute to protect river banks from local erosions. Overall, the analysis of the literature revealed that we are still far from a complete understanding of the scour mechanism at bridge pier with debris accumulation, particularly when sills are used as protection measures. In fact, the existence of Phase 4 caused by the direct impact of the downward flow on the sill represents a source of uncertainty when using such type of countermeasures. Consequently, more tests are needed to clearly identify the range of hydraulic conditions for which such countermeasures result to be effective in controlling scour phenomenon. Furthermore, it is also important to provide clear criteria to optimize the location of sills in the presence of debris accumulations. These issues represent future lines of research and may stimulate scientist to deepen such aspects. Acknowledgements This study was supported by FABRE – “Research consortium for the evaluation and monitoring of bridges, viaducts and other structures” (www.consorziofabre.it/en) through the project “M.Hy.Bridge” - Modelling Hydraulic risk at Bridges. Any opinion expressed in the paper does not necessarily reflect the view of the funder.The two authors equally contributed to the paper. References Chiew, Y.M., 1995. Mechanics of riprap failure at bridge piers. Journal of Hydraulic Engineering, 121(9), 635-643. Ghorbani, B., Kells, J.A., 2008. Effect of submerged vanes on the scour occurring at a cylindrical pier. Journal of Hydraulic Research, 46(5), 610 619. Grimaldi, C., Gaudio, R., Calomino, F., Cardoso, A.H., 2009a. Control of scour at bridge piers by a downstream bed sill. Journal of Hydraulic Engineering, 135(1), 13-21. Grimaldi, C., Gaudio, R., Calomino, F, Cardoso, A.H., 2009b. Countermeasures against local scouring at bridge piers: Slot and combined system of slot and bed sill. Journal of Hydraulic Engineering, 135(5), 425-431. Kumar, V., Ranga Raju, K.G., Vittal, N., 1999. Reduction of local scour around bridge piers using slots and collars. Journal of Hydraulic Engineering, 125(12), 1302-1305. Lança, R.M., Fael, C.S., Maia, R.J., Pêgo, J.P., Cardoso, A.H., 2013. Clear-Water Scour at Comparatively Large Cylindrical Piers. Journal of Hydraulic Engineering, 139(11), 1117–1125. Melville, B.W., Chiew, Y., 1999. Time scale for local scour at bridge piers. Journal of Hydraulic Engineering, 125, 59–65. Melville, B.W., Dongol, D.M., 1992. Bridge pier scour with debris accumulation. Journal of Hydraulic Engineering, 118(9), 1306-1310. Melville, B.W., Sutherland, A.J., 1988. Design method for local scour at bridge piers. Journal of Hydraulic Engineering, 114(10), 1210–1226. Moncada-M, A.T, Aguirre-Pe, J., Bolivar, J.C. et al., 2009. Scour protection of circular bridge piers with collars and slots. Journal of Hydraulic Research, 47(1), 119-126. Odgaard, A.J., Wang ,Y., 1987. Scour prevention at bridge piers. Hydr. Engrg. 87, R.M. Ragan, ed., National conference, Virginia, pp. 523-527. Pagliara, S., Palermo, M., 2008. Plane plunge pool scour with protection structures. Journal of Hydro-Environment Research, 2(3), 182 - 191. Pagliara, S., Palermo, M., 2020. Effect of pressure fluctuations and flow confinement on shear stress in jet-driven scour processes. Water, 12(3), 1 – 13, Article number 718. Pagliara, S., Carnacina, I., Cigni, F., 2010a. Sills and gabions as countermeasures at bridge pier in presence of debris accumulation. Journal of Hydraulic Research, 48(6), 764-774. Pagliara, S., Palermo, M., Azizi, R., 2015. Scour control at bridge piers using macro-roughness elements. Proceedings of the Institution of Civil Engineers: Water Management, 168(4), 174-188. Pagliara, S., Roy, D., Palermo, M., 2010b. 3D plunge pool scour with protection measures. Journal of Hydro-Environment Research, 4(3), 225 - 233. Palermo, M., Pagliara, S., 2020. Teaching Hydraulics and Hydraulic Structure Design with Leonardo da Vinci. Journal of Hydraulic Engineering, 146(5), Article number 04020035. Palermo, M., Pagliara, S., Roy, D., 2021. Effect of debris accumulation on scour evolution at bridge pier in bank proximity. Journal of Hydrology and Hydromechanics, 69(1), 108-118. Zarrati, A.R., Nazariha, M., Mashahir, M.B., 2006. Reduction of local scour in the vicinity of bridge pier groups using collars and riprap. Journal of Hydraulic Engineering, 132(2), 154-162.