Effect of bridge pier diameter on maximum depth of scour impacts on the environment

Abstract

This study uses a physical experimental model to investigate the scale effect of cylindrical bridge piers on local scour. Non-dimensional public relations are developed after determining the effective parameters. Experiments are carried out to estimate the maximum scour depth around cylindrical piers with 10, 20, 30, 40, 60 and 100 mm in diameter in a laboratory channel for well-sorted gradation of sediment particles. The average diameters of sediment particles are 0.5 and 0.7 mm under clear water conditions and the relative speeds are 0.67, 0.76, 0.86 and 0.95. Scour around the piers of Naderi and Fifth Bridges in Ahvaz is measured and the results are compared to the physical model results. This indicates that for the piers of less than 30 mm in diameter, the relative scour depth is just a function of the particle Froude Number. In addition to this, it is related to the ratio of the pier diameter to the flow depth for larger piers. The actual data collected from the mentioned bridges pier scour are compared to the physical experimental results. Accordingly, it is observed that the physical experimental results are highly agree with the actual one.