Experimental investigation of the equilibrium scour depth below submerged pipes both in live-bed and clear-water regimes under the wave effect

Pipelines are the key structures to carry fluids such as oil, petroleum, gas and water; any inadequate design induces bottom stability problems causing unintended consequences. In the present study, the equilibrium scour depth below submerged pipes due to regular waves was investigated experimentally. During the experiments various pipe diameters, bed material grain sizes and wave characteristics were used. The novelty of the study is that the experiments were performed both in live-bed and clear-water regime conditions. The analysis of the experimental data showed that the equilibrium scour was correlated with Shields parameter as well as Keulegan-Carpenter number, especially for live-bed scour condition. However, in the case of clear-water scour, the Keulegan-Carpenter number was found as a unique non-dimensional parameter that dominates the scour phenomenon. New empirical relations were also proposed for clear-water and live-bed scour separately.