Jets to control scour around circular bridge piers

It is common for engineers to use countermeasures to protect hydraulic structures against scour. This study aims to explore the effect of jet injection through the pier body as a pier-scour countermeasure. Laboratory experiments were conducted in two different flow depths (10.5 and 28 cm) using 1-jet and 3-jet injections, different jet locations, and angles between the jets under clear-water conditions. The experimental data showed that the most optimal case in terms of pier-scour depth reduction occurred for lower flow depth, higher jet flow rate, and angle between the jets equal to 90 degrees. Moreover, the jets are able to reduce the scour depth, scour volume and upstream slope of the scour hole up to 37.5%, 57%, and 25% for flow depth of 10.5 cm and 31.2%, 37%, and 57% for flow depth of 28 cm, respectively. By increasing the number of jets, turbulent kinetic energy increases, leading to the pier-scour depth decreasing.