Experimental and numerical impact of pier arrangement using collars on scour depth

Abstract

ABSTRACT This paper studied the scour around bridge piers by conducting laboratory experiments and numerical simulation using Sediment Simulation In Intakes with Multiblock option (SSIIM) program. Six pier models were investigated under different flow conditions in sandy soil for two cases: piers with and without a protective plate (collar). The models were arranged as follows: one pier, two piers side by side, two piers tandem, three piers triangular (1 × 2), three piers triangular (2 × 1), and four piers square (2 × 2). It was found that the relative scour depth (d s /y t ) where d s is the local scour depth and y t is water depth, increases as Froude number (F n ) increases for all models. Two Piers tandem model with a collar significantly reduced scour depth around the piers by over 80% compared to unprotected models. The collars effectively reduced the formation of vortices and minimized the detrimental impact on the sediment around the pier. The simulated results using the SIIM program are consistent with the experimental results, with an error of 10%. Scouring depth relationships were also deduced that are useful in bridge piers protection design in similar cases under the same conditions.