Experimental Investigation of Water-Flow Impact on Slit Dams with Varying Slit Widths

Slit dams, a common type of check dam, are engineered to retain coarse sediment while allowing finer particles to pass through. During the interception of granular flows, a separation of water and sediment typically occurs, beginning with the initial impact and continuing through subsequent deposition stages. To fundamentally understand the mechanisms by which slit dams separate solid-liquid mixtures, it is essential to first isolate and examine the hydrodynamic impact of water on the dam structure in detail.

In the design of slit dams, the width of the slits between piers and the dam height are critical parameters. To investigate the effect of different slit widths, experiments were conducted in a rectangular transparent flume with a length of 1.58 m set at a fixed slope of 15°. Three slit configurations, labeled A4, A5, and A6 (representing arrangements with 4, 5, and 6 piers respectively), were tested in the flume. During the experiments, miniature pressure sensors were used to sample pressure fluctuations, and a high-speed camera operating at 400 fps was employed to capture the flow behavior. This setup allowed the detailed process of flow impacting the slit dams to be fully recorded for statistical analysis. The results indicate that the impact process can be divided into three stages: turbulent, stable, and decay. The maximum average impact force and overflow depth showed no significant difference across the different slit widths. The hydrograph for the A5 configuration, which exhibited high turbulence, demonstrated a longer duration and slower pressure decay, followed by A6 and then A4.