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

Changes in cohesive sediment density due to consolidation can cause signicant changes in dam foundation stress and reservoir site permeability. The consolidation process in the Karkheh dam reservoir was investigated in this study using a settling column and varying the initial sediment concentration from 50 to 150 gr/lit. The initial sediment concentration, initial settlement height, and temperature are effective parameters for settling cohesive sediments. In addition, the effects of the bed elevation of the 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 with the initial concentration. The concentration of the settled sediments decreased with the initial height in a non-linear trend. 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.