This paper focuses on the impulsive forces observed in the tension cables of a slack-anchored floating silt curtain in waves. The characteristics of the impulsive tension are described through the results of model tests. Numerical methods for the prediction of the impulsive tension are proposed and compared with the experiments. The dependence of the impulsive tension on the representative parameters such as dimensions and elasticity of curtain members is discussed by using the model.
Recently silt curtains have been increasingly used to prevent waters at dredging or reclaiming sites in the sea from becoming turbid. However, the hydrodynamic forces acting on such a flexible structure have not been investigated well and the design criteria have not been established. The floating silt curtain treated in this study consists of floats, tension cables and curtain canvases as shown in Fig. 1. The curtain canvases are hung vertically from the surface floats to the specific water depth and extended by two horizontal tension cables both at the top and at the bottom of the curtain. When the floating silt curtain is anchored slack in regular waves, it oscillates periodically in such a way that it is pushed forward by waves in a half period of the motion and in turn it is drawn back in the other half period. Large impulsive forces are observed in the tension cables at the moment when the curtain is tightened up in each half period. Although this impulsive tension seems to be one of the most important factors in designing a floating silt curtain, experimental results show that the magnitude of the tension strongly depends on the material characteristics of a tension cable such as elasticity.