TY - GEN
T1 - Flow structures around a circular bridge pier with a submerged prism at upstream
AU - Ranjbar-Zahedani, Mohsen
AU - Keshavarzi, Alireza
AU - Khabbaz, Hadi
AU - Ball, James
PY - 2019
Y1 - 2019
N2 - Previous investigations have indicated that local scour around bridge piers and abutments causes around 60% of waterway bridge failures. In order to decrease the potential of pier-scour failure, the authors previously proposed an upstream prism as a new countermeasure against local scour. The proposed prism was examined in a comprehensive experimental program to find the most efficient size, submergence ratio, and installation location of the prism. The experimental results showed that the submerged prism could reduce around 40% of the maximum scour depth, and 60% of the scour-hole volume. In this study, in order to find out how this submerged prism affects the flow structure around the pier and reduces the pier-scour, the flow structure analysis was conducted using particle image velocimetry (PIV). The velocity components were measured for two cases of a single circular pier with and without the submerged prism. Analysis of the results indicated that the proposed prism could change the flow structure at the upstream and downstream of the pier. In fact, this submerged prism formed a wake region behind itself, and the bridge pier was located at this wake region. The produced wake resisted the down-flow at the upstream side of the pier and also disturbed the formation of the horseshoe vortices around the pier. In addition, this submerged prism reduced the strength of wake vortices behind the pier. Consequently, the pier-scour was significantly reduced by the substantial changes in the flow structure.
AB - Previous investigations have indicated that local scour around bridge piers and abutments causes around 60% of waterway bridge failures. In order to decrease the potential of pier-scour failure, the authors previously proposed an upstream prism as a new countermeasure against local scour. The proposed prism was examined in a comprehensive experimental program to find the most efficient size, submergence ratio, and installation location of the prism. The experimental results showed that the submerged prism could reduce around 40% of the maximum scour depth, and 60% of the scour-hole volume. In this study, in order to find out how this submerged prism affects the flow structure around the pier and reduces the pier-scour, the flow structure analysis was conducted using particle image velocimetry (PIV). The velocity components were measured for two cases of a single circular pier with and without the submerged prism. Analysis of the results indicated that the proposed prism could change the flow structure at the upstream and downstream of the pier. In fact, this submerged prism formed a wake region behind itself, and the bridge pier was located at this wake region. The produced wake resisted the down-flow at the upstream side of the pier and also disturbed the formation of the horseshoe vortices around the pier. In addition, this submerged prism reduced the strength of wake vortices behind the pier. Consequently, the pier-scour was significantly reduced by the substantial changes in the flow structure.
KW - bridges
KW - foundations and piers
KW - prisms
KW - scour at bridges
KW - streamflow
UR - http://hdl.handle.net/1959.7/uws:57203
U2 - 10.11159/icgre19.124
DO - 10.11159/icgre19.124
M3 - Conference Paper
SN - 9781927877524
BT - Proceedings of the 4th World Congress on Civil, Structural, and Environmental Engineering (CSEE'19), Rome, Italy, 7-9 April 2019
PB - Avestia Publishing
T2 - World Congress on Civil_Structural_and Environmental Engineering
Y2 - 7 April 2019
ER -