DES Modeling of Erosional Forces around Streamlined Piers and Implications for Scour Countermeasures

摘要

This study employed the detached eddy simulation (DES) numerical model to investigate the pier streamlining effect on dynamic turbulence intensity around bridge piers and the implication of such an effect on bridge local scour potential from a geomechanical perspective. A total of four test cases with piers having sequentially increased streamlining features were simulated. Comparison of the simulation results revealed that streamlined pier helped to reduce both the number and intensity of coherent vortices upstream of the pier. In addition, quadrant analysis of flow velocity in the horseshoe region showed that pier streamlining weakened the sweep and ejection events, the primary cause of sediment entrainment. The maximum bed shear stress gradually decreased as the pier streamlining extent increased. Findings from this study suggest that pier streamlining can serve as a scour countermeasure alternative; the numerical results also suggest that traditional excess shear stress theory on scour is at least incomplete; other factors, such as pressure fluctuation, momentum exchange between external and pore flow, and additional soil properties, should be taken into account.