Comparative Study of Scouring Around Bridge Piers

Excessive scouring around bridge piers is one of the main causes for bridge failures. Scour is not easily noticeable because it is hidden under the channel flow. Scour around a bridge pier is a challenging problem to planners and hydraulics researchers because of the adaptation of some empirical formulas. The basic reason of such adaptation of empirical formulas is due to lack of monitoring of such complex problem, and hence, the mechanism of scouring is not fully understood. Most of these scour prediction empirical formulas was based primarily on flume experiments. Thus, the knowledge of precise maximum scour depth for a given hydraulic and geotechnical condition is essential for proper design of foundation of the bridge piers as under predicted scour depth will lead to bridge failures, and over prediction of scour depth will lead to unnecessary construction costs. Since most of the scour prediction equations are based on laboratory experiments, it is important to analyse the hydraulic characteristics of the river before and after the construction of the bridge. In this study, analysis has been carried out to understand the influence of different parameters such as sediment size and the shape of the pier using different empirical equations. In India, Indian codes for scour estimation uses Lacey’s regime equation for scour depth estimation for the hydraulic design of bridges, which are having certain limitations. Thus, the objective of this study is to obtain a better understanding of the mechanism which causes scouring by considering hydraulic and geotechnical characteristics. Therefore, in the present study, an attempt has been made to investigate the effect of different parameters on scour around bridge piers. The results obtained were compared with equations and models used by other researchers and found that Lacey’s equation is giving over predicted values than other empirical equations.