Effect of Slot on Reduction of Scouring Around the Vertical Abutment

Abutments are used to protect erodible river banks. This structure is subjected to scouring due to flow convergence at the nose of structure. Therefore، countermeasure methods should be employed in order to prevent financial damages and life hazards. One of these methods is to use a slot. The main application of a slot is to deviate and change the down flow at the upstream region of an abutment. Also it reduces the power of vortices around the abutment. In this research، parameters such as depth، hole dimensions and time development of scoring process were measured around a vertical abutment. Operation of the slot was then evaluated at different height، depth، width and distance from the abutment nose and compared with unprotected abutment. The results showed that the models for which the slot was installed near the wall under the bed with the depth equal to the width of the abutment had the best performance. The amount of scour reduction for different models was 11. 8 to 43 percent.