11 / 2025-04-24 11:27:11

Local scour below a power cable and the influence of bed ripples

Laboratory experiments were conducted to investigate scour development around a partially embedded circular cylinder, representing a subsea power cable, under steady currents. A focus is placed on the influence of embedment depth (e/D) on equilibrium scour depth (Sv,eq). Although existing models describe this relationship, variations in fitted coefficients across studies suggest uncertainty, potentially due to differences in scour initiation methods and the influence of bed ripples under live-bed conditions. In the present study, experiments with cylinders embedded in rippled beds revealed that sand ripples reduce scour rates by lowering near-bed velocity. As ripples migrate from upstream, they interact with the developing scour hole, altering its geometry and depth. This interaction introduces uncertainty in estimating Sv,eq, particularly at higher e/D values, where the prolonged scour timescale allows ripple migration to influence scour development before equilibrium is reached.