Author(s): Shaolin Yue; Huan Zhou; Rui Wang

Linked Author(s): Huan Zhou, Rui Wang

Keywords: Dunes migration; Maximum scour depth; Around bridge Pier; Prediction model

Abstract: The removal of sediments from river bed around a bridge pier causes a local scour. This local scour is one of the major causes of many bridge failures so far so forth. It was statistically found that the scour was accountable for about 60% of bridge failures (FHWA, 1988; Lagasse et al., 1997) resulting in loss of lives and huge economic losses. From 1996 to 2005, at least 1502 bridge failures were documented in the United State, of which 58% were the result of the hydraulic conditions (Hunt, 2009). Up to now, there are still many bridges collapsed every year in China due to deep local pier scour. The maximum scour depth of the pier is one of key parameters for bridge design engineers for the sake of the safety of bridges. Up to now, there are numerous empirical formulas for the calculation of the maximum scour depth around bridge piers proposed by Breusers et al. (1977), Melville and Coleman (2000), Gao et al. (1993), Melville (1997), Richardson and Davis (2001), Sheppard et al. (2014), and Aksoy et al., (2017), etc. Although there are so many models for the prediction of the local pier scour depth, nevertheless it is still very difficult to be properly predicated sometimes. For many bridges, their sited beds are consisted of sands, where significant large dunes often migrate due to running waters or waves. It is found the dune heights in rivers could be as large as few meters. For a steady flow, the migration of dunes would yield a non-steady scour depth at the pier, which means there is a maximum scour depth during the dune passing through the scour pit. However, how the dune migration affects the scour process around the pier, and the maximum scour is still not crystally clear. In this study, experimental tests were carried out to investigate the scour hole evolution process via dunes migrate through and the maximum scour depths at the pier were analyzed. Finally, a formula for the maximum scour depths at the pier is proposed based on the HEC-18 model and present experimental data.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221652

Year: 2022