EXPERIMENTAL STUDY OF LOCAL SCOUR AROUND CIRCULAR PIER UNDER HYDROGRAPHS SUCCEEDING STEADY FLOW

Local scour around bridge piers and foundations, as a result of flood wave, is one of the major causes of their failure. In this study, local scour around circular pier due to five different hydrographs succeeding steady flow was studied under clear water conditions. The experiments were carried out in the rectangular flume 18.6 m long, 0.80 m wide and 0.75 m deep with uniform sediment bed material D-50=1.68 mm. Five types of hydrographs were generated by the adjustment of the pump rotational speed. The plexiglass circular pier diameter was 11 cm. The development of the scour hole was recorded by two video cameras. The measured temporal scour depths were compared with the results obtained from the empirical relation proposed by Oliveto and Hager (2005).