Effects of hooked-collar on the local scour around a lenticular bridge pier

Farooq, R., Azimi, A. H., Ur Rehman, Tariq, M. A. and Ahmed, A. (2023) Effects of hooked-collar on the local scour around a lenticular bridge pier. International Journal of Sediment Research, 38(1), pp. 1-11. (doi: 10.1016/j.ijsrc.2022.07.002)

Abstract

This paper presents the results of comprehensive laboratory experiments to investigate the effects of hooked-collar on the scour development around a vertical pier with a lenticular cross section. The flow around the pier was uniform, steady, and under the clear-water condition. The axial scour profiles for cases without and with a lenticular hooked-collar were measured and the effects of hooked-collar dimensions and elevation from the bed were examined. To compute the efficiency of hooked-collar for scour prevention, the results of local scour for a bridge pier without a collar and a bridge pier with a plain collar, without a hooked wall, were used as benchmark data sets. A wide range of hooked-collar geometries such as the ratio of collar width to the pier width, Wc/Wp, ranging from 1.5 to 3.5, the ratio of hooked-collar wall height to the pier width, Hc/Wp, ranging from 0.15 to 0.6, and the ratio of collar elevation to the pier width, Ec/Wp, of −0.5, 0, and 0.5 were tested. The experimental results indicated that the equilibrium scour depth decreased with the ratio of hooked-collar to the pier width when Wc is twice the pier width, Wp. For Wc/Wp > 2, the scour depth was similar to the tests with an infinitely large pier width. In addition, the scour depth consistently reduced as the hooked-collar wall height, Hc, to the pier width, Wp, approached 0.3. The highest scour reduction efficiency was achieved when the hooked-collar being placed on the bed surface. Empirical models were developed for prediction of maximum scour depth near the lenticular bridge pier with a modified collar. The results showed that the volume of scour hole around a lenticular pier increased non-linearly with the maximum scour depth and it was independent of the hooked-collar geometry.

• Item Type: Articles
• Additional Information: The work presented here was partially supported by the NSERC Discovery grant No. 421785.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ahmed, Afzal
• Authors: Farooq, R., Azimi, A. H., Ur Rehman, Tariq, M. A., and Ahmed, A.
• College/School: College of Science and Engineering > School of Engineering
• Journal Name: International Journal of Sediment Research
• Publisher: Elsevier
• ISSN: 1001-6279
• ISSN (Online): 2589-7284
• Published Online: 06 July 2022