The Effect of Stone Aggregate Size on Energy loss in Gabion Stepped Spillway

Abstract In this paper, the issue of energy losses in gabion stepped Spillway and the effect of grain size on stone materials on it is investigated. Laboratory models of 1: 5 scale overflows for steps 2 and 3 were made with heights of 40 and 60 cm, respectively. The stone materials were prepared as round stones from borrowed sources based on the scale model with dimensions of 4, 6 and 8 cm, equivalent to the normal size of the stones used in gabion structures. The models were installed in a 50 cm wide hydraulic flow with a discharge capacity of up to 65 liters per second. The results show that energy losses in rocks with a diameter of 4 cm are higher than in other cases. Also, by increasing the number of steps from 2 to 3 steps in gabion overflows, the efficiency of energy losses increases. In all cases, the efficiency of energy losses in these overflows decreases with increasing flow rate. Construction of gabion stairwells up to 3 steps will increase the efficiency of energy losses in the laboratory environment and consequently in nature.