Study on the effect of preventing the spread of pollutants due to double installation of siltfence

Previous studies have shown that siltfences reduce the effect of preventing the spread of pollutants when flow velocity was increased. However, under the present circumstances, it may be necessary to use siltfences even under the condition that flow velocity is high. On the other hand, there is also an example that installation of multiple siltfences can efficiently prevent pollutants. In this study, a hydraulic experiment was conducted for quantitative evaluation of the diffusion prevention effect of pollutants using silefences under high-speed flow. As a result, it was found that the pollutants were more trapped by the influence of the first siltfence and the reduction of the puffing amount of the second siltfence. The deformed shape of the second siltfence was reproduced by using the previously proposed estimation formula with appropriate experimental constants. This effect was confirmed in the experiment using plane wave tank. (author)