Clear-water scour evolution at dual bridge piers

For the efficient design of bridge pier footings, computation of time-evolution of scour depth around bridge piers is essential. In this paper, a semi-empirical model is developed to estimate the temporal variation of clear-water scour depth at a couple of identical cylindrical uniform piers in tandem arrangement. The experiments are carried out using different pier size, pier spacing, and flow intensities. The model development is based on sediment continuity approach and volumetric sediment transport rate from the scour hole using a sediment pickup function. The model results are presented as design charts giving the relation between dimensionless scour depth and time for practical use. Results of the proposed model are in relatively good agreement with the experimental results, in the tested range