Abstract

In this experimental study, the effects of particle-size uniformity, number of steps, stone arrangement mode (regular or irregular), and stone shape (roundedness) on energy dissipation in gabion stepped spillways were investigated. Laboratory models of the spillways were constructed at a geometric scale of 1:5, with heights of 40 cm and 60 cm for the two- and three-step configurations, respectively. Rounded stones were sourced from borrow materials and scaled to model sizes of 4, 6, and 8 cm (corresponding to 20, 30, and 40 cm in the prototype). These materials were arranged in both regular (structured) and irregular (random) configurations and installed in two- and three-step spillway models within a 50 cm-wide hydraulic flume with flow rates up to 65 L/s.

The results indicated that energy dissipation was highest for 4 cm stones in the regular arrangement. Additionally, increasing the number of steps from two to three enhanced the energy dissipation efficiency of the gabion stepped spillways. In all cases, the efficiency of energy dissipation decreased with increasing flow rate. Therefore, the use of gabion stepped spillways with up to three steps can improve energy dissipation efficiency under laboratory conditions and potentially under field conditions. Comparison with previous studies revealed that using angular (sharp-cornered) stones produces higher energy dissipation efficiency than rounded stones in gabion stepped spillways.