Ali Mahdian Khalili - Ph.D. Candidate, Faculty of Civil Engineering, Babol Noshirvani University of Technology, Iran, Mazandaran, Babol
Mehdi Hamidi - Associate Professor, Faculty of Civil Engineering, Babol Noshirvani University of Technology, Iran, Mazandaran, Babol
Pouria Akbari Dadamahalleh - Ph.D. Student, Faculty of Civil Engineering, Babol Noshirvani University of Technology, Iran, Mazandaran, Babol

Sometimes, debris such as tree trunks and leaves are transported by the river flow during floods downstream where bridges are built, and they often accumulate in a rectangular shape upstream of the bridge pier. Blockage of the bridge pier due to debris accumulation affects the scouring pattern of the river and can increase it. Therefore, in this research, the scouring pattern around the cylindrical bridge pier with the accumulation of rectangular debris upstream was investigated in the laboratory. ۱۴ tests were conducted for the two cases of single bridge pier and bridge pier with rectangular debris located on the surface of the riverbed under clear water conditions and scouring patterns and maximum scouring depth values were extracted. Results show that in the relatively shallow depth of the flow (y/D=۱~۱.۶۷), the maximum scour depth increased up to ۱۰% compared to the control condition, but with the increase of y/D=۲~۳, ds reduces compared to the control condition. The scouring patterns show that in relatively shallow depths (y/D=۱.۳۳), the presence of debris extends the location of high scouring depths (ds/D>۱) up to ۲D in the longitudinal distance.

Bridge Pier, Rectangular Debris, River Morphology, Scour