The Effect of Installing Immerse Vanes on Scouring Around Bridge Abutments

To control scour, it is first necessary to examine the scouring mechanism and the flow patterns around the abutment. By constructing of the abutment, the approaching flow pattern around it is disturbed. In addition, this brings about an increase in the average flow velocity due to narrowing, and the three-dimensional patterns of the flow are formed around the bridge abutment, which is the main cause of the local scour around the structure. To protect the bridge from scouring, two measures have been developed in the past; a) the direct methods and b) the indirect methods, which modify the flow pattern and reduce the power of vortex vortices. One can mention the use of roughness, sluts, submerged vanes and immerse vanes. One of the problems in using submerged vanes is the scouring formed around these structures because these vanes are placed on the bed and the three-dimensional patterns around them form and cause the scour around the vanes and eventually lead to their destruction. On the contrary, immerse vanes are located above the bed and their destruction from bed scouring is impossible. Application of immerse vanes was first studied by Shafai-Bejestan et al. (2016) in order to control the scouring of the outer river banks in a 180 degree flume bend. Their results showed that by installing the immerse vanes on the outer bank of the bend, the amount of scour depth decreases in the area of ​​the outer bank toe. On the other hand, the use of these vanes to control the scour of the bridge abutments has not been studied so far. Therefore, the present research has been carried out. In this study, the immerse vanes with four different distances, each with four different flow conditions, were tested to determine the most appropriate distance between the plates.