عنوان مقاله [English]
Nowadays design and construction of concrete, rocky and earth structures is one of the proper ways to control and divert water from rivers. Gabion structures, and the most important of them gabion stepped spillways, have become more common and taken into attention due to the considerable effect of the steps on energy dissipation of flow, appropriate stability, being economic, easy implementation and raising the mixture oxygen level of water. The aim of present study is to investigate the energy loss, the hydraulic jump characteristics and to evaluate the effect of gabion porosity installed on stepped spillway on energy dissipation. In order to achieve, five physical models were constructed including three gabion stepped spillway models with porosity of 35%, 40% and 45%, an impervious stepped spillway and a chute. The slope of all models were considered constant and equal to 1:2(vertical:horizontal). The results indicate that gabion stepped spillways are able to reduce the hydraulic jump characteristics including conjugate depths, length of the hydraulic jump and the roller jump in comparison with the impervious one to an acceptable amount. The amount of energy loss of gabion stepped spillways is higher than impervious stepped spillway. The maximum energy dissipation value is referred to the gabion stepped spillway with porosity of 45%, which was about 86% and this amount of energy loss is 8% more than the impervious stepped spillway.