Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 51 4 2019 10 23 Laboratory Study of the Effects of Step Number, Slope and Particle Size on Energy Dissipation in Gabion Stepped Weirs Laboratory Study of the Effects of Step Number, Slope and Particle Size on Energy Dissipation in Gabion Stepped Weirs 749 756 2865 10.22060/ceej.2018.13984.5527 FA Sina Razi PhD candidate, University of Tabriz, Tabriz-Iran Farzin Salmasi Ali Hoseinzade Dalir Professor, University of Tabriz, Tabriz-Iran Journal Article 2018 01 20    Gabion stepped weir is a simple hydraulic and environment friendly structure that can be used to dissipate flow energy in downstream of dams or to control downstream erosion of various structures. Most researches have been related to concrete and rigid stepped spillways, so studies on gabion stepped weirs are very small. In this research, using the experimental method and physical model, various components that affected the energy loss in gabion stepped weirs were studied and comparisons with other studies by researchers were also made. The flow passes in gabion stepped weir was carried out both in overflow and inflow (both simultaneously) and the amount of energy dissipation along the structure was calculated based on the energy relation. In this study, completely uniform particles with three diameters (d50) of 10, 25 and 40 mm were used. The height and width of physical models made of gabion stepped weirs were 60 cm and 40 cm respectively, with stairs of 3, 6 and 12 and height of stairs 5, 10 and 20 cm and the slope of the weirs are 1:1, 1:2 and 1:3 (2 and 3 horizontals, 1 vertical). In the gabion stepped weirs, the downward slope of the weir had a negligible impact on the energy dissipation. As the number of steps increased (for constant h/l), the energy loss was decreased. The average diameter of the particles of 10 mm for y0/Hw<0.92 and the average diameter of the particles of 40 mm for y0/Hw>0.92 had the highest of relative energy loss. Due to the fact that the stone materials used in this research are of a broken type, it is recommended that further research be carried out on round stone materials.    Gabion stepped weir is a simple hydraulic and environment friendly structure that can be used to dissipate flow energy in downstream of dams or to control downstream erosion of various structures. Most researches have been related to concrete and rigid stepped spillways, so studies on gabion stepped weirs are very small. In this research, using the experimental method and physical model, various components that affected the energy loss in gabion stepped weirs were studied and comparisons with other studies by researchers were also made. The flow passes in gabion stepped weir was carried out both in overflow and inflow (both simultaneously) and the amount of energy dissipation along the structure was calculated based on the energy relation. In this study, completely uniform particles with three diameters (d50) of 10, 25 and 40 mm were used. The height and width of physical models made of gabion stepped weirs were 60 cm and 40 cm respectively, with stairs of 3, 6 and 12 and height of stairs 5, 10 and 20 cm and the slope of the weirs are 1:1, 1:2 and 1:3 (2 and 3 horizontals, 1 vertical). In the gabion stepped weirs, the downward slope of the weir had a negligible impact on the energy dissipation. As the number of steps increased (for constant h/l), the energy loss was decreased. The average diameter of the particles of 10 mm for y0/Hw<0.92 and the average diameter of the particles of 40 mm for y0/Hw>0.92 had the highest of relative energy loss. Due to the fact that the stone materials used in this research are of a broken type, it is recommended that further research be carried out on round stone materials. https://ceej.aut.ac.ir/article_2865_6efe898e2e642347410549ff01c044fe.pdf