Optimizing flow diversion structure as an effective pier-scour countermeasure

Abstract

To reduce local scour around bridge piers, a mitigation measure requiring a submerged triangular flow diversion structure is proposed. Different dimensions, locations, and submergence ratios were examined experimentally. Using Taguchi’s method to minimize the number of alternative tests, 27 alternative tests were undertaken to ascertain the optimum size and location for the structure. Compared to the no flow diversion structure situation, it was found that the optimized structure resulted in a 40% reduction in the maximum scour depth and a 60% reduction in scour volume. Also, an experimental study of the flow field was conducted to investigate the influence of the structure on flows. Results showed that the structure influenced the down-flow and horseshoe vortex and consequently reduced the scour. Based on the investigation presented herein, a flow diversion structure is a simple and easy approach for mitigation of scour at existing and new bridges.

Keywords:

• Bridge pier
• erosion control
• flow-structure interactions
• hydraulic models
• particle image velocimetry (PIV)
• river training structures
• turbulence–sediment interactions