Bridges

Scour has been identified as one of the main causes of bridge failures in Australia and worldwide. Accurate estimation of scour around bridge piers is challenging as it requires a comprehensive analysis of the interactions between fluid, soil and bridge structure. The mechanism of scour is influenced by many factors including geometry of the channel, dynamic properties of the flow, soil conditions, geometry of the bridge piers and abutments. Numerical modeling of flow around bridge pier using computational fluid dynamics (CFD) is fundamental step in determining the effective parameters that control sediment removal around the pier and scouring of the bed. This study aims to investigate the effect of key parameters such as flow velocity, flow depth and sediment coarseness on scour initiation through a sensitivity analysis. A multi-interaction numerical model is developed using CFD package Fluent 16, and prediction of upstream and downstream velocities is validated against experimental data. The developed model is used to generate bed shear stress data for a number of clear water scenarios for sandy bed in order to investigate the effect of different parameters on the scoured area. Results show that the mean flow velocity, characterized by the Froude number, has a dominant effect in controlling scour initiation among the variables considered in the current study. These results also form the basis for development of a closed form analytic model for estimating scour around bridge piers against the wave loading.