Investigating the effect of oblique bed sill on bridge pier scouring with circular cross-section

Subject Areas : Article frome a thesis

saeed gohari ¹ , MARZIEH REZAEI ²

1 - Bu Ali sina university
2 - BU ALI SNA UNIVERSITY, HAMEDAN, IRAN

Received: 2018-04-01 Accepted : 2020-01-26 Published : 2020-02-20

Keywords: Scour, Bridge pier, Bed sill, Non-cohesive sediments,

Abstract :

Local scouring around the pier is one of the main reasons for the instability of the bridges. Providing appropriate methods for predicting and controlling scour depth is one of the important issues that have been considered. Various methods have been proposed to control the scouring around the bridge pier. In this study, the effect of using the bed sill on scouring around the cylindrical bridge pier under clear water conditions has been investigated and compared in non-cohesive sediments. The bed sill has been placed at the downstream of the pier and its effect on reducing the scouring has been evaluated by changing distance between and the pier and sill geometry. In this research, a pier with 50 mm diameter was used. The results showed that bed sill setting has effect on scour reducing. Also, the distance and the shape of the sill have the greatest effect on reducing the scour. The placement of the straight and oblique bed sill at the backside of the pier resulted in a decrease of 11% and 16%, respectively, in the maximum of scour depth. By increasing the distance of sill to the oblique pier, its protective effect was reduced. Also the oblique bed sill more reduces the amount of scour around the pier relative to the straight bed sill and prevents the scour hole from developing to upwards.

References:

1)       Azevedo, M. L., Leite, F. C, and Lima, M.M.C.L. 2014. Experimental study of scour around circular and elongated bridge piers with and without pier slot. ASCE, Journal of Hydraulic Engineering, 132(2): 154-161

2)       Breusers, N. H. C., Nicollet, G. and Shen. H. W. 1977. Local scour around cylindrical piers. IAHR, Journal of Hydraulic Research, 15(3): 211-252.

3)       Chiew, Y. M. 1992. Scour protection at bridge Piers. Journal of Hydraulic Engineering, ASCE, 118(9): 260-269.

4)       Chiew, Y. M. and Lim, S. Y. 2003. Protection of bridge piers using a sacrificial sill. Proc. ICE Water, Maritime and Energy 156(1): 53–62.

5)       Ettema, R. 1980. Scour at bridge piers. Report No.216, University of Auckland, School of Engineering, New Zealand.

6)       Grimaldi, C., R., Gaudio, F., Calomino Cardoso, A. H. 2009. Control of scour at bridge piers by a downstream bed sill. Journal of Hydraulic Engineering, 135(1): 13–21.

7)       Heidarpour, M. Afzalimehr, H. and Khodarahmi, Z. 2007. Local scour protection of circular bridge pier groups using slot. Journal of Agriculture, Science and Natural Resource., 4(3).1-12. (In Persian)

8)       Kumar, V., Ranga-Raju R. K. G. and Vittal, N. 1999. Reduction of local scour around bridge piers using slots and collars. Journal of Hydraulic Engineering, ASCE, 125: 1302-1305.

9)       Melville, B. W. and Sutherland, A. J. 1988. Design method for local scour at bridge piers. ASCE, Journal of Hydraulic Engineering, 114(10): 1210-1226.

10)   Melville, B. W. and Chiew, Y. M. 1999. Time scale for local Scour at bridge piers, Journal of Hydraulic Engineering, ASCE, 125 (1):59-65.

11)   Melville, B. W., Coleman, and S. E.  2000. Bridge scour. Water Resources Publications, Highlands Ranch, Colorado.

12)   Melville, B. W. and A. C. Hadfield. 1999. Use of sacrificial piles as pier scour countermeasures. Journal of Hydraulic Engineering, ASCE, 125(11): 1221-1224

13)   Pagliara, S., Carnacina, L., and Cigni, F. 2010. Sills and gabions as countermeasures at bridge pier in presence of debris accumulations. Journal of Hydraulic Research. 48(6): 764–774.

14)   Parola, A. C., Mahavadi, S. K., Brown, B.M. and El-Khour Y. 1996. Effects of rectangular foundation geometry on local pier scour, Journal of Hydraulic Engineering, ASCE, 122 (1):35-40.

15)   Raudkivi, A. J., and Ettema, R. 1983. Clear water scour at cylindrical piers, Journal of Hydraulic Engineering, ASCE, 109(3): 339-350

16)   Saadati Pachekenari, S. S. Esmaeili Varaki, M. and Fazl Ola, R. 2014. Experimental Investigation of Effect of sill Location on Local Scour Around Inclined Bridge Piers Group. Journal of Water and Soil. 28(2): 406-419. (In Persian)

17)   Zarrati, A. R., Nazariha, M., and Mashahir M. B. 2006. Reduction of local scour in the vicinity of bridge pier groups using collars and riprap. ASCE, Journal of Hydraulic Engineering, 132(2): 154-161