A NEW ANALYTICAL BRIDGE PIER SCOUR EQUATION

When a bridge is built across an alluvial channel, the obstruction of the flow by the bridge piers induces higher velocities and vortices that cause scour of the channel bed around the piers. If this scour reaches the foundation level of the bridge piers, the bridge might collapse. Bridge pier scour is the leading cause of bridge failure. In Egypt, concerns about bridge pier scour is one of the important reasons for limiting the increase of the current flow releases from High Aswan Dam above the current maximum. Due to the importance of bridge pier scour, many investigators have worked on this critical subject but most have built their analysis on laboratory flume data that have simplified conditions and scale effects. When applying the existing empirical equations for predicting bridge pier scour to field cases, the scour depths are over-predicted which means increased construction costs. A new analytical equation for predicting bridge pier scour is developed herein based on an energy balance theory. The developed equation expresses equilibrium bridge pier scour depth in terms of flow velocity, flow depth, bed sediment specific gravity and