Effect of simultaneous use of cable and bed sill scour countermeasures around a cylindrical pier

Abstract

The simultaneous use of cable and bed sill (CBS) scour countermeasures around a cylindrical pier was investigated. With the aim of finding the best combination of CBS in terms of scour depth reduction, 16 laboratory assessments of local scour were conducted. These experiments were also used to investigate the turbulent flow structure and sediment entrainment. The best combination of simultaneous CBS reduced the scour depth by about 34%. The flow structures around an unprotected pier (reference case) and for the best CBS configuration were compared by employing turbulent analysis methods. Two-dimensional bursting events were used to understand the stochastic nature of the flow structure around the pier. The turbulence characteristics and occurrence probabilities of bursting events confirmed the effect of the combination of CBS on reducing the scour depth. In addition, of all the bursting events, ejection events were found to have the highest transition probabilities.