Temporal variation of clear water scour at cylindrical bridge piers

Abstract

Computation of temporal variation of clear water scour is important for the design of bridge pier footings. Previous studies indicated that very long flow duration was needed to achieve equilibrium scouring situations. However, the corresponding durations in the prototype conditions may yield considerably larger values than time-to-peak of the design flood. Therefore, there is a need to estimate the temporal variation of scour depth. This study deals with the development of a new semiempirical method for temporal variation of clear water scour at cylindrical bridge piers using the sediment continuity approach. A recent sediment pickup function proposed for sloping beds is used to formulate the rate of sediment transport out of the scour hole. Results of the proposed method agree well with experimental results. The findings of the proposed method are also compared with some recent empirical methods.Key words: bridge, pier, scour, clear water, sediment pickup.