A Field Study of Scour at Bridge Piers in Flood Plain Rivers


Abstract: Scour at bridge piers has long been recognized as an issue of considerable importance as it pertains to pier hydraulic design, according to a large number of scour studies conducted over the past few decades. Despite this long record of study, pier scour remains the most significant cause of bridge failure. The current study, which was based on field evaluations of pier scour failures in rivers with cohesionless beds, focused on a general view of the scouring process. The study was based on the results obtained from the investigation of 6 bridges on 3 rivers in Fars Province, Iran. The hydraulic effects of flow depth and velocity, sediment characteristics such as specific gravity, internal friction angle, particle size, and particle size distribution, and bridge pier geometry were considered. A certainty analysis based on field data was performed to provide a very rough estimate of risk. Statistical and physico-mathematical methods were used in analyzing the data. When possible, a simple comparison was made between the depth of scour and some existing empirical formulae. Among these formulae, the Hanco, CSU, Veiga, and Neill equations exhibited rather good agreement with the field data; however, the Laursen and Inglis equations overestimated scour depth.

Keywords: Field study, Iranian rivers, Pier scour, Scouring process

Full Text: PDF