Experimental study of the consolidation of the cohesive sediments Case study: Karkheh dam reservoir

The physical and chemical properties of cohesive sediments have been determined. The consolidation mechanism was also investigated in various scenarios by changing the initial sediment concentration from 50 to 150 gr/lit. In the experiments, cohesive sediment samples of the Karkheh dam reservoir were tested using settlement columns. The initial sediment concentration, initial settlement height, and temperature are among the effective parameters on the settlement of cohesive sediments. In addition, the effects of the bed elevation of reservoir, as well as the scale effects on the settlement of cohesive sediments, were also studied. The results showed that the initial free settlement process and the hindered settlement phase take more time than self-weight consolidation settlement stages by increasing initial sediment concentration. Therefore, at an initial sediment concentration of 25 g/l and 150 g/l, the samples began self-weight consolidation after 1.5 h and 17.5 h respectively. The results also showed that the final average concentration increased linearly by the initial concentration. The concentration of the settled sediments decreased with a nonlinear trend by the initial height. In addition, under the same initial conditions, by increasing the diameter of the settlement column, the final concentration of the settled sediments first decreased and then increased.