Page - 185 - in Book of Full Papers - Symposium Hydro Engineering

Table 1 Range of sediment size used in previous studies Range of sediment size (mm) Authors 2.12 Curi et al. (1977) 0.375-1.80 Mashauri M-I (1986) 0.1875-0.75 Mashauri M-II (1986) 0.320-2.7 Esen (1989) 0.063-0.25 Mashauri M-III (1986) 0.09-0.30 IPRI (1989) 0.175 Paul et al. M-I (1991) 0.05-1.00 Paul et al. M-II (1991) 7.64 Paul et al. M-III (1991) 0.055-0.931 Athar et al. (2002) 0.074-0.3 Keshavarzi and Gheisi (2006) 0.08-2.00 Niknia et al. (2011) In previous studies, sediment injection was done with different methods. Athar et al. (2002) carried out sediment injection by a device composed of a circular-shaped cylinder and sediments lied within it. The device was installed in the floor of the vortex settling basin inlet channel and the sediment injection rate was controlled by a cable. Keshavarzi and Gheisi (2006) performed sediment injection by a device that worked like an hourglass. Niknia et al. (2011) mixed sediments with water in a tank and performed sediment injection by obtaining a specific concentration. The sediment injection device used in this study is seen in Figure 3. For sediment injection, a certain volume of the desired sediment was poured into the injection device tank with a volume 50 liters (funnel-shaped tank) and dry sediment were regularly getting out of the device and poured into the channel by rotating the roller inside it that had three longitudinal grooves. The roller rotation was done by an electric motor that had a controllable revolution. The precision of this control was in revolution per second. This device was placed at a distance of 1.5 m from the upstream channel of the vortex settling basin. 5 15 25 35 45 55 65 75 85 95 0 10 20 30 40 50 60 70 80 90 100 mm CLAY SILT SAND GRAVEL SAMPLE NO.1 FINE U.S. STANDARD SIEVE SIZES 4102040100200 NO. 4.75 190.420.0750.010.002 3/8 3/41 2 3 6 201510 IN. 5081001010.1 COBBLE FINE COARSECOARSEMEDIUM Figure 2 Gradation curve of the injected sediments to the vortex settling basin with d50=0.22mm Figure 3 The sediment injection device 185