Experimental study of the local scour around the two piers in the tandem arrangement using ultrasonic ranging transducers

Single pier characterization has been predominately considered by a majority of the recommended equations, although all bridge structures are laid on the group of piers. The behaviour of scour must be extensively examined in order to identify the parameters that primarily influence the bridge scour. The primary aim of the study is to investigate the effect of the densimetric Froude number, temporal scour development and pier spacing (Ps) on scour depth and propose a new equation for scour depth estimation using GEP (Gene Expression Programming). For profoundly understanding and continuous monitoring of scour evolution, SeaTek Ultrasonic ranging transducers have been used. The results exemplify that non-dimensional scour depth increases with the increase in the densimetric Froude number and velocity of flow. The effect of pier spacing shows that the scour depth increases as the pier spacing increases at a certain Ps range, then it decreases. The maximum scour depth at the front pier was observed 24% greater than the single pier, and 14% rear pier. The comparison of the proposed GEP equation with the well-known equation and Experimental results shows that the GEP is better prediction tool for scour depth.