Shear Stress Ratio on the Unprotected Bed in Conditions with and without Riprap at the Bridge Span

Author

Assistant Professor, Road, Housing and Urban Development Research Center, Tehran, Iran.

Abstract

Scour at the shallow abutment foundation during floods is a common cause of bridge failure. In some cases, the bed is reinforced with riprap. There are several advantages and disadvantages of using this method. One of the disadvantages of using flush riprap aprons with the bed is that heterogeneous roughness (riprap versus native bed materials) alters the flow and manifesting as strong secondary currents. This flow can increase the shear stress and the scour depth in the unprotected bed. To study the subject, a conceptual model for determining the shear stress ratio in the unprotected bed in both with and without riprap has been investigated. In developing the conceptual model, numerical simulation tests in a flexible bed have been used. Then, the validation of Flow3D numerical model is presented and the mentioned model is used to simulate the flow in two cases with and without riprap in the rigid bed. In a rigid bed compare to flexible bed, computational and hardware costs are significantly reduced. The shear stress ratio in the unprotected bed is calculated and the quadratic polynomial equation is fitted for different roughness ratios. The coefficient of determination in each case indicates the appropriate correlation of the stress ratio in the two modes of flexible and rigid bed.

References

-Adams, M.T., Schlatter, W., and Stabile, T., (2007), “Geosynthetic reinforced soil integrated abutments at the bowman road bridge in defiance county, Ohio”, Proceedings of Geo-Denver 2007: Geosynthetics in Reinforcement and Hydraulic Applications, p. 1–10. American Society of Civil Engineers, Reston, VA.
-Bojanowski, C., Lottes, S.A., Flora, K. Suaznabar, O., Shen, J. and Kerenyi, K., (2017), “Development of a computational approach to detect instability and incipient motion of large riprap rocks”, Argonne National Laboratory, U.S. Department of Energy laboratory.
-Cardoso, A.H., Simarro, G., Fael, C., le Doucen, O. and  Schleiss, A.J., (2010), “Toe protection for spill-through and vertical-wall abutments”, Journal of Hydraulic Research, Vol. 48, No. 4, pp. 491-498.
-Dey, S. and Barbhuiya, A.K., (2005), “Flow field at a vertical-wall abutment”, Journal of Hydraulic Engineering, Vol. 131, No. 12,
pp. 1126-1135.
-FHWA, (2017), “Hydraulic performance of shallow foundations for the support of vertical-wall bridge abutments”, Publication NO. FHWA-HRT-17-013.
-Hong, H.A. and Irfan, A., (2019), “Scour around an Erodible Abutment with Riprap Apron over Time”, Journal of Hydraulic Engineering, Vol. 145, No. 6, 06019007.
-Karimaei Tabarestani, M. and Zarrati, A.R., (2018), “Reliability analysis of riprap stability around bridge piers”, Journal of Applied Water Engineering and Research, DOI: 10.1080/23249676.2018.1497556.
-Khademghaeiny, G.N., Abrishami, J., Zarrati, A. R., Karimaei Tabarestani, M., Badali Mashahir, M., “Riprap design at bridge piers with limited scouring”, Scientia Iranica, Article in Press. Accepted Manuscript, Available Online from 18 December 2018.
-Kocaman, S., (2014), “Prediction of backwater profiles due to bridges in a compound channel using CFD”, Advances in Mechanical Engineering, Article ID 905217, 9 pages.
-Lagasse, P.F., Clopper, P.E., Pagán-Ortiz, J.E., Zevenbergen, L.W., Arneson, L.A., Schall, J.D., and Girard, L.G. (2009) “Bridge scour and stream instability countermeasures”, Hydraulic Engineering Circular No. 23”, Report No. FHWA-NHI-09-111. Federal Highway Administration, Washington DC.
-Lauchlan, C.S., Melville, B.W., (2001), “Riprap protection at bridge piers”, Journal of Hydraulic Engineering, Vol. 127, No. 5, pp. 412–418.
-Melville, B.W., van Ballegooy, S., Coleman, S.E., and Barkdoll, B. (2006), “Countermeasure toe protection at spill-through abutments”, Journal of Hydraulic Engineering, Vol. 132, No. 3, pp. 235–245.
-Petersen, T.U., Sumer, M.B., Boegelund, J., Yazici, A., Fredsoee, J., and Meyer, K.E., (2015), “Flow and edge scour in current adjacent to stone covers”, Journal of Waterway, Port, Coastal, and Ocean Engineering, vol. 141, No. 4.
-Tippireddy, R.T.R., (2017), "Air injection as a scour countermeasure at bridge piers", Open Access Master'sThesis, Michigan Technological University.
Journal of Transportation Research
Volume 17, Issue 4 - Serial Number 65
October 2020
Pages 145-156

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