Investigation of Bed Load Transport Through Rockfill Dam

Due to environmental considerations, using permeable control structures in rivers have been widely welcomed by engineers working on different aspects of rivers. Impermeable structures such as rockfill dams could provide more suitable hydraulic conditions for flow discharge within rivers by allowing sediments pass through their body so that the environmental impacts at structures downstream may be reduced to its lowest rate. Although there are a large number of researches carried out on the hydraulics behavior of the flow passing through fine and coarse materials, there is, however, a few studies on passing bed load through dam body of rockfill structures. In this experimental research, to provide suitable condition for bed load to pass through dam body, a coarser layer of materials has been used at the bottom of the dam. Using dimensional analysis and data provided from laboratory tests, a relationship to estimate the amount of bed load passing from coarse materials has been introduced, and in this regard, the available equations to estimate bed loads, are modified as well. The mean relative error of the new equation was estimated as 64.7% while it is estimated as 101% for Meyer- Peter and Muler modified relationship. Furthermore, it is found that at the range of the experiments carried out in this research, using coarser materials at the bottom of rockfill dams has no significant effects on the amount of bed load passing through dam body.