Suction effects on bridge pier scour

• Main Author: Qi, Min
• Other Authors: Chiew Yee Meng
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/42857
• Institution: Nanyang Technological University

This experimental study investigates how the application of suction at different location affects local scour around bridge piers under clear-water conditions. The results show that suction has a profound effect on pier-scour development, and the extent of the influence is dependent on the location of the suction source. When the suction source is located upstream of the bridge pier, the equilibrium scour depth is reduced by up to 50% at -2.4<x/D<0 and x/D ≈ -6.4 with Qs/Q0 = 2%, where x = horizontal distance along the streamwise direction between the suction source and pier center, Qs and Q0 = suction flow rate and undisturbed total flow rate, respectively. The data also show that for the suction source that is located downstream of the pier, the equilibrium scour depth is reduced by 30% at x/D ≈ 6.4. The reason is because suction influences pier scour both directly and indirectly. The former imposes a downward force onto the self weight of the sand particles, making them less susceptible to erosion, while the latter is related to the re-adjustment of the velocity profile downstream of the suction source.