Investigation of the effect of gabion-shaped obstacles on sedimentation

Abstract

Sedimentation in reservoirs is one of the most important factors in reducing the useful life of large dams. The main factor in moving sediments is density currents, so that researchers in recent years have proposed various solutions to control these flows, the use of obstacles is known as one of the most effective solutions. By understanding the function of these currents and the factors affecting them, an effective step can be taken to control or eliminate them. Therefore, in this study, the effect of changes in the height of the permeable obstacle with a diameter of one centimeter under the influence of various parameters has been investigated. Thus, changes in obstacle height (1, 1.5 and 2 times the body of density current), discharge (1, 1.5 and 2 lit/sec), concentration (10 and 15 gr/lit), slope (0/75, 1/25 and 0/75%) was examined. The results showed that the three parameters of slope, concentration and discharge in this study are the factors affecting the flow moment and with increasing each of these parameters, the efficiency of obstacles with dimensional ratio of height 1 and 1.5 decreases , However, in the obstacle with a dimensionless ratio of height 2, the performance of the obstacle is improved, so that when the current collides with the obstacle, a lot of turbulence is created, which causes a significant reduction of the density current head, so that the average rate of head flux reduction The dimensional ratios of 1, 1.5 and 2 times were about 32, 45, 92%, respectively.