Scour Hole Characteristics around Abutment in Compound Channel

Scour around abutments is one of the main causes of failure at bridge foundations. Hence, it is important to cater for scour around these structures to an acceptable safety level. The design of scour countermeasures around abutments needs an estimate of the temporal variation and characteristics of the scour hole formed. This study focuses on the scouring around 45° wing wall setback abutments in a compound channel. As literature showed previous studies were mainly on scour depth around thin vertical abutments in rectangular channels. The measurements of the scour depth, length, width, surface area and volume of the scour hole at different time intervals until its equilibrium scour conditions have been conducted. The effect of abutment length and time on the characteristics of the scour hole is analyzed, and the prediction of scour hole dimensions at equilibrium is proposed based on dimensional analysis. It is found that the influence of increasing the abutment length on the depth and width of the scour hole is greater than on scour length. Furthermore, the influence of this parameter on surface area is greater than on scour volume.