Journal of Hydraulic Structures

Journal of Hydraulic Structures

Reduction of Scour Around Bridge Piers using Combined Cylindrical Protector and Riprap

Document Type : Research Paper

Authors
Ferdous Mirsalari 1
Mahmood S. Bajestan 1
Seyed Mahmood Kashefipour 1
Mohammad Bahrami Yarahmadi 1
Kheirollah Khodemi 2
1 Department of Hydraulic Structures, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
2 Housing and Urban Development Research Center, Tehran, Iran.
10.22055/jhs.2026.51695.1377
Abstract
In this study, the use of cylindrical protector, which is a new method for controlling scour around the base, has been investigated to protect the riprap layer. Two series of experiments carried out. first, a control experiment (experiment A) was conducted using a cylindrical pier of 4.5cm in diameter without using any protection. Then, a permeable cylindrical protector (CP) of 13.5 cm in diameter was used as pier protector (experiment B1), the results of which showed that the maximum scour depth decreased by 12.8% compared to experiment A. Subsequent tests included a 4.5 cm radius of riprap covering around the pier (Test B2), a 13.5 cm radius of riprap covering around the protective cylinder only (Test B3), and Test B4 with a 18 cm radius of riprap covering around the pier as well as the CP and was tested under the same flow conditions. The results of these experiments showed that the maximum scour depth was reduced by 81, 31, and 100 percent, respectively, compared to the Test A. The rocks particles were stable throughout the test and edge erosion was negligible. In Test B2, the gravel surface in front of the pier was depressed due to the extrusion of fine bed particles (0.7 mm in diameter) from the pores of the rocks, which was due to the lack of using a layer of filter between the rocks and the sand bed, but no edge erosion was observed. In Tests B2 and B4, negligible edge erosion was observed
Keywords
Hydraulics
protective cylinder
rock pile
scour
bridge foundation protection
Subjects
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