Laboratory Study of the Effect of Sill, Submerged Vanes and Groyne on Scour Depth around the Piers Group

In this research, the effect of submerged vanes height with quasi-triangular arrangement and groyne with fixed height and foundation at two different heights on the scour of the base group of stairs has been investigated. In this paper, 29 experiments with the same laboratory conditions have been studied in a rectangular canal with dimension of 13 m in length, 1.2 m in width, 0.8 m in depth and with zero longitudinal slope. The maximum increase of scour depth due to the installation of groyne is 89.1% and with the installation of submerged vanes, the maximum reduction of scour depth with a height of 0.44 D (D is pier diameter) is equal to 79.3% compared to the control. The performance of 1D-height groyne was better than the 0.44D-height submerged vanes, as in the first base at Froude number of 0.25, the amount of scour depth reduction was 88%. The longitudinal dimension of scouring has been increased 72.7% by installing a sill at Froude number of 0.15. The installation of submerged vanes and the abutment have reduced the longitudinal dimension, as the reduction amount of abutment longitudinal dimension with 1D-height at Froude number of 0.25 was equal to 54.2.