Widths, types, and configurations: Influences on scour behaviors of bridge foundations in non-cohesive soils

Local scour has been regarded as one of the key factors that cause bridge failures. The complex interactions between flow and bed materials will result in a scour hole around structures. This process compromises their stability and the shift in the natural frequency of a bridge. Among various foundation types, pile groups and caissons are widely used in deep water. In this study, flume tests are conducted to investigate the scour behaviors of foundations with different widths, types and configurations, including cylindrical, cubic, cubic with 45° attack angle, and pile groups. The scour characteristics of these foundation types and configurations are analyzed according to the observation from flume tests. In conjunction with the experiments, computational fluid dynamics models are built to further analyze the scour mechanism. Then, influences of foundation wides have been carried out together with an elaborate description of scour evolution has been addressed to unveil the scour mechanism. Numerical simulations were carried out under the same conditions as the experiments but with wider ranges of foundation diameter. Recommendations are proposed based on a comprehensive analysis of experimental phenomena and computational models, which intends to provide guidance for practice in mitigating the risk of bridge scour.