Effect of bridge pier diameter on maximum depth of scour impacts on the environment
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Effect of bridge pier diameter on maximum depth of scour impacts on the environment Narges Raeisi1 · Mehdi Ghomeshi1 Received: 18 March 2020 / Accepted: 22 September 2020 © Springer Nature Switzerland AG 2020
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. Keywords Clear water · Cylindrical pier · The relative speed · Scour
1 Introduction Investigation of the scour phenomenon is very important. The scour around structures such as bridges pier or bridge abutments or embankment need to be controlled otherwise, this could lead to irreparable damages. The instability of bridge piers is one of irreversible damages caused by the scour. Without applying an appropriate solution, it eventually leads to the demolition of the structure. Therefore, a study on the mechanism of the scour occurrence and the effective parameters on the amount of scour are a necessity [36]. Bridge piers across the river divert river flow, which results in scour around the piers. Every year, scour results in slippage of the bridge piers during flooding and the destruction of bridges is occurred. This cuts avenues for assistance in these regions and highlights the requirement for major study of this phenomenon. The prediction of scour and its consideration during the design of
bridges and implementation of design policies are crucial to the control and reduction of local scour [38]. Scour creates holes around piers and undermine the stability of the bridge. The force of the water flow against the pier and the separation of the stream lines are the main causes of scour around piers [9]. The pressure gradient resulting from the force of water against the pier diverts the surface stream lines of water downward toward the substrate in foreside of the bridge pier (or abutment). The flow of water hits the substrate and digs into it, then clashes with the mainstream, creating a horseshoe vortex. Horseshoe vortices are more active in foreside of th
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