Evaluation and Comparison of the Slots and Collars Performance in Reducing Scouring around Bridge Abutments

Document Type : Research Article


1 department of civil engineering, science and research branch, Islamic Azad university

2 Department of civil engineering, Science and research branch, Islamic azad University, Tehran , Iran

3 agricultural department, Islamic azad University, Ahvaz Branch


The bridge failure caused by the local scouring phenomenon around its piers or abutments is a common phenomenon. Therefore, some methods should be used to prevent the destruction of these structures. Slots and collars are among the tools that can be used for this purpose. Therefore, by conducting 49 tests in this research, we will examine and compare the performance of these two tools with new approaches around bridge abutments using an experimental model in different flow conditions. The results show that although the most effective slot model can reduce the dimensions and depth of scour hole by 61%, it cannot postpone the start of the scouring phenomenon and take the scour hole away from the abutment surroundings. However, for the most effective collar and highest Froude number, the scour hole reaches the base point after 120 minutes from the start of the test. In this collar model, the maximum depth of scour hole is shifted to a more distant point from the abutment, and the percentage of reduction in the depth of scour hole at the base point and erodible bed is 96% and 56%, respectively.


Main Subjects

1.Sumer, B. M., & Fredsøe, J. (2002). The mechanics of scour in the marine environment, Adv. Ser. Ocean Eng, 17.
2.Barbhuiya, A. K., & Dey, S. (2004). Local scour at abutments: A review. Sadhana, 29)5), 449-476.
3.Kwan, T.F. and Melville, B.W. (1994). Local scour and flow measurements at bridge abutments. J. Hyd. Res., ASCE, 32(5): 661–673.
4.Dongol, D. M. S., & Melville, B. W. (1994). Local scour at bridge abutments. Department of Civil Engineering, University of Auckland.
5.Ahmed, F., & Rajaratnam, N. (2000). Observations on flow around bridge abutment. Journal of Engineering Mechanics, 126(1), 51-59.
6.Dey, S., & Barbhuiya, A. K. (2006). Velocity and turbulence in a scour hole at a vertical-wall abutment. Flow Measurement and Instrumentation, 17(1), 13-21.
7.Kothyari, U. C., & Ranga Raju, K. G. (2001). Scour around spur dikes and bridge abutments. Journal of hydraulic research, 39(4), 367-374.
8.Melville, B. W. (1992). Local scour at bridge abutments. Journal of Hydraulic Engineering, 118(4), 615-631.
9.Grimaldi, C., Gaudio, R., Calomino, F., & Cardoso, A. H. (2009). Countermeasures against local scouring at bridge piers: slot and combined system of slot and bed sill. Journal of Hydraulic Engineering, 135(5), 425-431.
10.Kumar, V., Raju, K. G. R., & Vittal, N. (1999). Reduction of local scour around bridge piers using slots and collars. Journal of Hydraulic Engineering, 125(12), 1302-1305.
11.Dargahi, B. (1990). Controlling mechanism of local scouring. Journal of Hydraulic Engineering, 116(10), 1197-1214.
12.Chiew, Y. M. (1992). Scour protection at bridge piers. Journal of Hydraulic Engineering, 118(9), 1260-1269.
13.Kayaturk, S. Y. (2005). Scour and scour protection at bridge abutments (Doctoral dissertation, Ph. D. thesis, Department of Civil Engineering, Middle East Technical University )METU(, Ankara, Turkey).
14.Tafarojnoruz, A., Gaudio, R., & Calomino, F.(2012). Evaluation of flow-altering countermeasures against bridge pier scour. Journal of Hydraulic Engineering, 138(3), 297-305.
15.Tafarojnoruz, A., Gaudio, R., & Calomino, F. (2012). Effects of a slotted bridge pier on the approach flow. Proceedings of XXXIII Convegno Nazionale di Idraulica e Costruzioni Idrauliche IDRA 2012, 1-10.
16.Moradpour, M., Farsadizadeh, D., & Hoseinzadeh dalir, A. (2013). Study of collar effect on scour reduction around vertical semicircular bridge abutments. Journal of Iranian Water Research(IWRJ ), 6)11), 15-26. (In Persian).
17.Alem, Z., Ghomeshi, M., Mohammadi, S. (2013). The application of collar on the scour reduction at bridge rectangular abutment in composit channel. Irrigation and Water Engineering, 3(2), 29-41. (In Persian).
18.Alem, Z. (2013). Effect of netted collar on the scour of bridge abutment. MSc Thesis, Shahid Chamran University. (In Persian).
19.Kumcu, S. Y., Kokpinar, M. A., & Gogus, M. )2014). Scour protection around vertical-wall bridge abutments with collars. KSCE Journal of Civil Engineering, 18(6), 1884-1895.
20.Khozeymehnezhad,  H.,Ghomeshi, M. (2016). Experimental Investigation of Collar Performance with Rough Surface on Local Scour Reduction around Bridge Abutment with Rectangular Section. Water and Soil Science, 26(1-1), 213-223. (In Persian).
21.Mehrzad, R., & Hakimzadeh, H. (2017). Experimental Investigation of the Effects of Slotted Cone-Shaped Piers on Scour Reduction Due to Steady Flows. International Journal of Offshore and Polar Engineering, 27(03), 318325.
22.Hajikandi, H., & Golnabi, M. (2017, June). Y-shaped and T-shaped slots in river bridge piers as scour countermeasures. In Proceedings of the Institution of Civil Engineers-Water Management (pp. 1-11). Thomas Telford Ltd.
23.Khosravinia, P., Malekpour, A., Hosseinzadehdalir, A., & Farsadizadeh, D. (2018). Effect of trapezoidal collars as a scour countermeasure around wing-wall abutments. Water Science and Engineering, 11(1), 53-60. 
24.Mansuri, B., Hosseinzadeh Dalir, A., Farsadizadeh, D. (2016). Experimental Study of Shape of Spur Dikes in Series to Control Scour in River Bends. Water and Soil Science, 26(1-1), 69-81. (In Persian).
25.Breusers, H. N. C., & Raudkivi, A. J. (1991). Scouring Hydraulic Structures Design Manual. Balkerna, Rotterdam, 2.
26.Chiew, Y. M., & Melville, B. W. (1987). Local scour around bridge piers. Journal of Hydraulic Research, 25(1), 15-26.
27.Melville, B. W., and Coleman, SE.(2000). Bridge Scour. 5thedn, Colorado: Water Resources Publishing, 550p.
28.Melville, B. W., & Chiew, Y. M. (1999). Time scale for local scour at bridge piers. Journal of Hydraulic Engineering, 125(1), 59-65.