Bridge scour protection design method based on combined grouting and riprap protection

Abstract

Pier foundation scour is one of the leading causes of bridge failure, highlighting the urgent need for practical and effective scour protection strategies to ensure the structural safety and serviceability of bridges under flood conditions. A bridge scour protection design that combines grouting and riprap, was proposed and evaluates its effectiveness compared to single protection approaches. The reliability of scour simulations conducted with Flow-3D was validated by replicating the Melville experiment. Subsequently, clear-water scour simulations were carried out to analyze the critical initiation shear stress of the grouted regions around the pile foundations. In parallel, fixed-bed scour simulations were used to evaluate the turbulence-modulating effects of riprap based on flow velocity distribution around the pile. A comprehensive simulation of the combined protection method was then performed to assess its impact on scour depth and pit morphology. The comparative analysis revealed that the combined grouting and riprap protection significantly reduced scour depth, altered flow patterns more effectively, and led to more favorable scour pit geometries than either grouting or riprap alone. The integrated use of grouting and riprap provides a promising solution for pier foundation scour protection.

Keywords

scour protection / rock throwing / grouting / joint protection design / numerical simulation