Author(s): I. Masoud Zokaei; S. Amin Salamatian; Amir Reza Zarrati
Linked Author(s): Amir Reza Zarrati
Keywords: No Keywords
Abstract: In the present work the efficiency of a collar around a rectangular bridge pier is investigated under various bed shear stresses. Experiments showed that with installation of a collar the depth of the scour hole reduces and the equilibrium time of scour increases especially at lower shear stresses. To reduce the time of experiments in the present work, low density sediment was used as the bed material. Experiments were conducted at clear water with 4 relative shear stress ▲ where μ is upstream undisturbed bed shear velocity and μ_*c is the bed material critical shear velocity. Pier aligned with the flow as well as skewed at 5o, 10o, 20o were tested. Results of experiments showed that when the pier was aligned reduction of ▲ from 0.95 to 0.75, reduced the maximum depth of scour from 2.2D to 1.6D where D is the pier width. Moreover, the time of equilibrium increased 1.43 times when ▲ reduced from 0.95 to 0.75. Similar results were also found for skewed piers.
Year: 2009