The experimental investigation of the effect of submerged vanes on the reduction of the local scour around the bridge abutment

Local scour involves removal of material from around piers and abutments as the flow accelerates around the obstructed flow area. This phenomenon is sometimes the main reason for the bridge failure. Different structures such as submerged vanes can be used to change the flow pattern and prevent scouring around the piers and abutments. In this study¡ the effect of submerged vanes on the reduction of the local scour around the bridge abutment was studied. Experiments were conducted in a compound cross section flume with non-cohesive sediments having diameter (d50) of 1 mm. Experiments were performed for two cases of with and without the presence of submerged vanes. Vanes with a length of 10 cm and height of 3.33 cm (L/H =3) were installed in front of the bridge abutment with an angle of 20 ° to the flow direction. They were used in three layouts of one row¡ two parallel rows¡ and two zigzag rows. The results showed that the geometric property of the scour hole developed in the nose of abutment was similar to those previous related studies. For all flow conditions¡ the results showed that the submerged vanes reduced the scour hole around the bridge abutment and moved the scouring away from the abutment to the center of channel. Furthermore¡ the performance of the layout of two parallel rows was better than the layouts of one row and two zigzag rows¡ and it reduced the maximum scour depth up to 87.81 %.